Animal Camouflage and Bioluminescence Notes PDF

John – Lecture 1 Terrestrial and aqua c animals have evolved many ways of being inconspicuous either to avoid being predated or for prey capture. Typically, this is achieved by using the substrate in some way such as: 1. Hiding under it 2. Hiding it in 3. Mimicking it Example: The snak...

John – Lecture 1 Terrestrial and aqua c animals have evolved many ways of being inconspicuous either to avoid being predated or for prey capture. Typically, this is achieved by using the substrate in some way such as: 1. Hiding under it 2. Hiding it in 3. Mimicking it Example: The snake eel mimics the surrounding substrate and burrows into it to ambush prey. Animals that camouflage themselves can do so in 3 ways: 1. Colour match the substrate such as the anemone shrimp. 2. They can structurally match the substrate which breaks up the outline of the body to be er blend into the substrate, the skin and underlying musculature needs to be modified. Example is stonefish – they are venomous. 3. Combina on of colour matching and structural matching to camouflage. Flounder and cigar wrasse (cigar wrasses also behaviourally mimic the sea grass) are examples. Crypsis: blending into surroundings, camouflage is one way to achieve this. Camouflage is the mechanism, crypsis is the goal. How can an animal reduce its conspicuousness in a habitat that doesn’t have any substrate? Animals can manipulate or reflect light to reduce their visibility. Some animals are transparent: To become transparent, you don’t want to sca er light because this creates contrast, you also don’t want to reflect light because then you will be seen. So instead, you want to minimise any disturbance to the path of photons to allow them to pass through you. Transparency is the only form of crypsis that involves the en re organism. If you want to make your whole body transparent every organ must be transparent. Therefore, organismal transparency can be par al (only part of the organism is transparent) or complete (the whole organism is transparent). Glass wing bu erfly: transparency is quite rare in terrestrial environment. This bu erfly has par al transparency. Transparency is much more common in aqua c environments. More specifically, it is mostly confined to deep sea oceanic environments. 95% of whole bodied transparent animals are marine and found in the mesopelagic zone (mesopelagic zone is found 200 – 1000 meters down has no light and no substrate). The factors the limit the evolu on of transparency and why it’s more common in the ocean are as follows: 1. Gravity – on land you must overcome the force of gravity. To live on the land, you must have dense muscles and ssues and the higher the density the more light that is reflected. Conversely in the water you don’t need to overcome gravity. 2. On land you come into direct contact with UV radia on from the sun and this is damaging the ssue so terrestrial species have pigments such as melanin to protect the sun, however such skin pigments make the ssue more visible. Species in the marine environment are limited from that constraint. 3. Refrac ve Index – this is an index measuring how different you are to your surrounding medium (does so mathema cally). On the sea floor there isn’t light but there is substrate where the animals can burrow. Closer to the seashore there is substrate to borrow in. Above the mesopelagic zone there is light so species can camouflage into surroundings. In mesopelagic zones there is no light and no substrate hence 95% of transparent species found here. Many Classes of Marine Animals that use Transparency such as: - Fishes - Crustaceans - Mollusca - Cnidarians - Nematodes - Annelids *The evolu on of transparency has evolved independently many mes.  Refrac ve Index: To become transparent, you need to minimize the difference between the medium and yourself in terms of the refrac on of photons (the degree to which you alter the path of photons). To be transparent you want photons to pass right through you. Smaller animals are more likely to be transparent than larger animals (the larval state of fishes tend to be transparent either par ally or completely). The same applies to shape. A spherical animal is more visible than an area of the same volume stretched out into a long thin tube. This is because transparency relies on the thickness of an object – transparency decreases as an animal becomes thicker. Other factors that govern whole animal transparency: 1. Vision: eyes have to absorb light in order to depolarize the rod cells that are located at the back of the re na. Therefore, transparent animals that possess eyes are more visible than ones that don’t. Transparent animals therefore tend to lose their eyes all together, they have greatly reduced eyes in terms of size. o E.g., Daphnia: Two morphs of daphnia that exist in the wild. They have the same body size, par ally transparent except for the gut and eyes. One morph has bigger eyes than the other. The morph with the bigger eyes has been found to have the higher risk of preda on. 2. Gut Content: if you eat an animal that is not transparent you become visible. Some transparent animals have evolved a special diet to only eat other transparent animals, or only eat transparent body fluids, or only eat the transparent parts of an animal in the case of animals that are par ally transparent. The other way to reduce this issue is to line the gastrointes nal tract with reflec ve cells to mask the contents. Squid: - Squid can manipulate the structure of their body wall, can change the colours of their skin using chromatophores, they also have iridophores that are light reflec ng cells above their eyes or on their skin which changes the apparent colour based upon the angle between the sender and the receiver. How to transparent individuals find each other during breeding? - Squid congregate during breeding season. Chromatophores: when they expand you see more pigment, when they contract pigment shrinks to a ny dot. Found in squids, cu lefish, and octopi. Iridophores: light reflec ng cells on squid (see above for more info). John – Lecture 2 Define Bioluminescence: Requires no external light source but there is the present of light and the process by which this light is created is happening en rely within the organism. The produc on and emission of cold light by a living organism, that func ons for its survival and propaga on. The crea on of this light results from a chemical reac on (chemiluminescence) in which the conversion of chemical energy goes to radiant energy. That process is excep onally efficient so very li le energy is given off in the form of heat, hence bioluminescence is known as cold light. Invertebrates the use bioluminescence: fireflies Bioluminescence organisms found across the planet with at least 17 phyla and 700 genera containing luminous species. The func onal role of bioluminescence is hard to discern in simple types of organisms such as bacteria and fungi. 80% of bioluminescent organisms are marine, with most being found in pelagic, mesopelagic, and benthic zones where there is very li le to no sunlight. Bioluminescence has been found in cephalopods, copepods, krill, deep sea fish, jelly fish, cone jelly, deep sea fish (MARINE). Fireflies, glow worms, click beetles, fungi, 1 type of bacteria (LAND). How does it occur? - A chemical reac on that releases energy but instead of the energy being released as heat it is instead being released as visible light. - Bioluminescence maximum for marine species falls within the range of 450 – 510 nm. - Terrestrial organism have predominantly a yellow green bioluminescent colour and fall between 540 – 560 nanometres. - In ocean water blue to green parts of the light spectrum is where luminescence is op mal.  - The colour of bioluminescence is tuned by the protein in which the light is created. How does it work? - Luciferase is a generic term for a clade of oxidated enzymes that produce bioluminescence. - Luciferin and the enzyme luciferase. Enzyme catalyses oxida on of luciferin (in some species the luciferin requires co factors such as ATP or magnesium). The oxida on of luciferin creates oxyluciferin. - Luciferins vary li le across species, even those who independently evolved. Some animals produced luciferin themselves whilst others obtain it through their diet. Intrinsic Bioluminescence - Define: Organisms that can synthesise own luciferin - Dinoflagellates bioluminescence blue/green colour – create blue sparkly ocean. Extrinsic Bioluminescence - Define: Organisms that absorb luciferin through other organisms – either as food or via symbiosis. The anatomic loca on of bioluminescence among organisms is very variable. However, in most organisms the key organ is the photophore (light emi ng organ). These photophores are normally made up of complex photogenic light emi ng cells. The photophore can be quite simple or as complex as the human eye. The bioluminescence reac on has also been detected in the stomach, secretory organs, and liver. However, in these places it is believed to be the result of synthesis. Most bioluminescent reac ons involve luciferin/luciferase, however some do not. The reac ons that don’t use luciferin instead use a chemical called photoprotein. Photoprotein in crystal jellies is called green fluorescent protein or GFP. Aequorin: a calcium ac vated photoprotein. Func ons of bioluminescence - Many of the func ons are s ll unknown.  - Counter-illumina on o A method of camouflage in which an animal produces light to match an illuminated background, such as the ocean surface. - Burglar Alarm o Atola Jellyfish is an example. When the water is disturbed organisms produce light flashes to either startle any poten al predators or illuminate the predator to one higher up the food chain. - Misdirec on o Bioluminescence secre ons are used by some organisms to distract or misdirect predators. - Distrac ve body parts o Some organisms are capable of cas ng off appendages to distract predators while they escape. - Lure Prey o They light up the area near by to see next meal be er, or lure prey to mouth such as plankton, whale or squid all of which are a racted to bioluminescence. Examples include cookie cu er shark and deep-sea angler fish. - Mate A rac on o The male Caribbean ostracod ( ny crustacean) uses bioluminescence signals of their upper lip to a ract females. - Illumina on of Prey Biofluorescence - Should not be confused with bioluminescence. - Biofluorescence: a natural process in which organisms absorb light (from sun) at one intensity, or wavelength, and emit it at a different wavelength. Absorbs blue light and emits it at a different colour (e.g., red, green, orange). - Thought that this may be used for communica on, intraspecific communica on related to ma ng or male to male compe on, and camouflage. - This is not a type of chemiluminescence. - If you turn off the light source and the light goes away its biofluorescent, however if the light doesn’t go away its bioluminescence. - Only occurs in the pho c zone where there is enough light to cause biofluorescence. - Green is the most common colour found in biofluorescence. How does biofluorescence work? - The energy of light form one or two photons excites an electron into a higher energy orbit. - No oxygen used in this process. Scien fic Applica ons of Bioluminescence - Components of bioluminescence systems such as aequorin have been used for monitoring cell levels of calcium. - In 1985 firefly luciferase was cloned to assess the amounts of ATP in a cell. - Green fluorescent protein (GFP) cloned in 1992, expressed in various organisms by 1994. It’s well established as an excellent tag for proteins, it will fluoroes when the protein is ac ve. - Luciferase-based systems are used in gene c engineering and biomedical research. John – Lecture 3 Deep = talking about extreme depth, below 1000m deep. Challenges of the deep: 1. High pressure – this is a problem for ssues because proteins that comprise the body wall have to deal with this pressure. 2. Absence of light – no solar radia on and no primary producers. 3. Cold temperatures – all animals are ectothermic. 4. A lack of strong current – transporta on of nutrients hindered, so animals in the deep are typically sessile. Low metabolic rates ea ng infrequently. The food resources have to come from above so are patchy and limited. So, you must be adapted to ea ng sporadically and gorging when there is food. Animals in the deep have low metabolic rates as they are remaining rela vely s ll to wait for food and not ea ng much. Animals have rela vely low amounts of skeletal muscle. Environment consists mainly of predators and scavengers. Many predators have evolved bioluminescence to lure prey to them. Protein Structures Coping with High Pressures: - With increasing depth, and increasing pressure, the water in a cell is squeezed and pushed out of the cell. So increasing pressure reduces intracellular water which impairs normal cellular processes such as the func on of enzymes (lock and key) – pressure can contort the structure of the enzyme which means enzymes and ligan don’t fit together properly. - Cell membrane – phospholipid (hydrophilic heads poin ng outwards, hydrophobic tails poin ng inwards). This phospholipid bilayer maintains ionic gradients between the inside and outside of cell. The pressure compresses the phospholipid bilayer together (cell is circular) when compressed it compresses in all direc ons. To overcome this problem deep sea animals, have a high propor on of phospholipid tails that contain dispropor onately more unsaturated fa y acids giving them bent hydrophobic tails which allow the membrane to withstand the high pressure whilst maintaining func on. Deep sea animals have low metabolic rates primarily due to minimal food. Size of mouth and gut tend to be huge in deep sea animals and this is due to sporadic food. They also don’t discriminate about what they eat, they are very opportunis c. A big mouth ensures that you can eat anything that is edible. Deep sea animals have greatly reduced musculature. Deep sea animals have 1/3 the muscle mass (in terms of protein) compared to surface dwelling fish. They do have more fat as this serves as an energy reserve and is more adaptable to high pressure. Metabolism decreases with Depth: - Glycoly c enzyme is an indicator of metabolic rate (converts pyruvate to lactate in the absence of oxygen). Lactate dehydrogenase (LDH) – enzyme, involved in cellular respira on. Ac vity of LDH decreases with increasing depth. Other Adapta ons: Refer to slide 12. Many have inward faced teeth so that any pierced pray cannot escape. Anglerfish: - Giant mouth, inward facing teeth, bioluminescence to a ract prey, small eyes, weakly muscularised body. - Males ectoparasites. Males dissolve their way through the female’s body wall to access her fluids and this is its only source of food. Gulper Eels: - Massive hinged jaw allowing them to eat prey of the same body mass as themselves. - Produce reddish light for a rac ng prey at the very p of their tail. - Flaccid snake like body that expands massively during and a er ea ng. - Ray-finned fish that are only superficially similar to eels. - Poor swimmers. - Opportunis c feeders. Typical Deep-Sea Habitats: - Found along ring of fire along the pacific rim – named due to tectonic ac vity. - Found where sea floor is expanding. - High biomass and diversity – possibly due to deep sea vents. - No light for photosynthesis so photoautotrophs cannot exist here. Therefore, li le oxygen. Very cold. Crushing pressures. Deep Sea Vent - AKA black smokers. - Temperature of ejected material is 300 – 400 degrees C. - Strong temp gradient of 400 C of ejected material compared to 2 C of surrounding sea water. - Sea floor is very porous so allows sea water to seep into that bedrock. There the water can mix with minerals, and then this mix is ejected by the black smoker ejec ng those nutrients back into surrounding sea water. Without the black smoker the surrounding sea water would be nutrient poor. Chemolithoautotrophic – fix carbon through oxidizing inorganic compounds. - Creates a 5 C to 40 C band of gradient where life can be supported. Community of Animals living at Deep Sea Vent - Ri ia pachyp la (tube worms) - Tube worms are the dominant sea vent creature in terms of biomass. - Central plume (red part) area where all elements and gases diffuse into the animal. These are then sent by the circulatory system into the celom. Within the celom is the trophosome. The trophosome consists of densely packed chemoautotrophic sulphur oxidizing bacteria. The chemical reac on occurring within the bacteria are processed into carbohydrates and nitrogen containing compounds. The tube worms take on the role of  primary producers in deep sea vents. They are considered to be a keystone species in these ecosystems. - In the 5 c to 40 c band there is a huge diversity of animal life. When there is a large diversity and biomass in a localized area it helps drive between species interac ons and leads to specializa on. - Bacteria can also be free-living forming mats of bacteria on rocks or living on the gills of bivalve mussels and clams. - Limpets and filter feeders act as primary consumers. - Secondary consumers such as fishes and crabs eat the primary consumers. - All of these organisms have high metabolic rates and high growth rates. This means that the absence of light and high pressures aren’t the limi ng factors of the deep but instead the inward flow of energy is. Ques on 1: How can vent animals cope with high levels of hydrogen sulfide? Hydrogen sulfide (HS) is toxic in all animals because it binds irreversibly haemoglobin. It also breaks down cytochrome c oxidase systems (needed for ATP genera on). These vent animals have an insensi ve form of haemoglobin that is insensi ve to HS, making it nontoxic. They have proteins in their blood plasma binding to HS allowing it to be removed from the body via excre on. Ques on 3: How do deep sea vent communi es populate new vents (dispersal mechanisms)? Larval stages of tube worms are chemotaxic meaning they move towards certain chemicals put out by vents. They can travel 100km or more and remain viable. Shaun – Lecture 1 Car laginous fishes have been around for over 400 million years and have been adapted to many different environments. Generally dived in 4 main groups: sharks, skates, rays, elephant sharks. Bony Fishes - 30,000 species of bony fishes - They have been around 40-50 million years. Feeding Dependent on: - Dietary needs which can vary from very small things such as plankton right up to marine mammals. - Levels of hunger dictates how o en they feed. - Ac vity pa ern – ac ve during night (nocturnal) or day (diurnal), are they migratory or territorial. - Diges on me – plankton could be digested quite quickly but a large animal might have to sit in the stomach longer. - Size and orienta on of the mouth – strategies might include suc on. - Environmental condi ons under which feeding occurs. - Sensory capabili es – how they detect where the prey is and what sort of environmental cues do they use to locate prey. - Risk of being predated on – if very brightly coloured might need to hide. - Method of ven la on – ram ven la on (need to con nue to swim) or buccal pumping (can remain s ll). - Propulsion – pelagic (roaming freely through the water column) or benthic (si ng on the bo om), accelera on, speed, and buoyancy. - Den on – cu ng, tearing, crushing. - Inges on method – some ingest whole, and others are more fussy. Feeding Strategies - Vary enormously. Sit-and-wait Strategies - Predators which are ambushing others. - The act of surprise is the biggest strategy here. - Spiracular ven la on – well camouflaged, si ng under sand etc. Reduce breathing so they aren’t obvious. - Camouflaged well in both the texture and pa ern. The colour of the skin will merge with environment. - Very well concealed. - Have lures – such as barbels, tail movement. Ac ve Searching and Targe ng - White and red muscle will indicate accelera on rate and sustained swimming speed.  - Thresher sharks have different propor ons of red and white muscle. - Red muscle requires oxygen rich environments (using lots of oxygen), is rela vely slow contrac ng, but gives the individual great stamina. Generally, about 10%. - White muscle is fast contrac ng, does not require an oxygen rich environment, and tends to become exhausted quickly. - May have brain and eye heaters, meaning there is an orbital rete (an area in the back of the eye and around the brain, made of high concentra ons of mitochondria which produce heat and can upregulate the surrounding ssue to 5c Celsius). Negate any change in the surrounding ssue as the animal dives into deeper colder water, allowing the neural ac vity of sense organs not to be affected by a reduc on in temperature meaning the firing rate is maintained, enabling the detec on of prey by the eye and the processing of sensory informa on to be maintained. (Generally, occurs in the big pelagic animals). Inges on - Inges on: the object of finally swallowing but there are a series of tasks that must occur before this: o Capture – animal must capture prey item. o Swallow whole – some species will swallow prey whole. o Den on – these can be for cu ng, tearing, or chewing. o The bite force can also impact suitable prey. o Taste receptors – final decision before inges on. - Den on o Mako Shark – Prey can’t escape once caught due to slope on teeth. o Tiger Shark – Not symmetrical. Moving caudally in towards the back of the jaw. Pronounced point so can pierce through prey. Shakes head from side to side, and according to orienta on of teeth it can deflesh and saw through flesh. Enormous pounds per square inch pressure. o Great White – Very symmetrical. o Most car laginous fishes are opportunis c however some have preferred prey. o True teeth have mul ple rows that are con nually being replaced generally within 5-10 days and progress forward. Con nual turnover of teeth, up to 30,000 teeth in life me. o Some species possess grinding plates – a lot of the s ngrays and benthic sharks have these. They are s ll hard and will come together with great force to crush prey. o Range of diet varies enormously. o Broad-nose seven gill shark have 4 different types of teeth. Spikey teeth, tricuspid teeth in central part of jaw, towards edges grinding teeth, large 4/5 prong scissor like teeth. - Bite Force o Dictates the type of prey. o Jaws evolved from the first gill arch and are not a ached to the skull. o BFQ (bite force quo ent) is dictated by orienta on and arrangement and number of muscles fibres within muscles. o Gape of jaw (how open it can get) is dictated by contrac on force and relaxa on force indica ng how big the jaw can get, this also effects suitable prey. - Suc on Feeding  o Mouth is opened crea ng nega ve pressure within oropharynx to draw in water and hopefully prey. o Generally, animals that sit on the bo om or exist around the bo om use this method. o Nurse Sharks – very quick, three stages (expansive, compressive, and recovery), almost no cranial eleva on, mean me to maximum gape is 32 msec. - Stunning Prey o Thresher shark makes a whip like mo on that stuns animals. Uses whip like mo on referred to as tail smacking. o S ngrays are sit and wait predators but also have spines (generally only use in defence, can be 1 spined and 2 spined). o Electric Ray – will stun pray using high voltage, freshwater and marine species, part of their muscles have changed over evolu on and are able to store energy this is called an electric organ, these banks of adapted muscle ssue can all discharged energy at once and give rise to very sharp but very short-lived voltage. Some electric organs can deliver a voltage in the hundreds of volts. Electric eel can discharge an electric volt of 720 volts. - Stealth – Counter Illumina on o Adap ons that have arisen in bony and car laginous fishes. o Upper dorsal surface of many animals is much darker than ventral belly – this is counter illumina on. This is a way of remaining undetected as a prey species or helping you catch prey if a predator species. Renders silhoue e invisible. o In the deep sea because light is very low, some animals have photogenic organs (photophores) which produce bioluminescent light which can match the downwelling light coming from above to cloak the silhoue e from any poten al predators looking upwards. The bioluminescence intensity can change as the animal moves up and down the water column. o Bioluminescent sharks (which cover ventral part of body) have a constant light output, so move up and down the water column un l light output of the photophores matches water column and they are at a iso-luminance depth. o Using the Sun – research has showed that great whites can approach prey while having the sun in a posi on that has them remain in shadow. This will improve prey detec on, avoid overs mula on of re nal photoreceptors as most sharks are designed to operate in the dim light (avoids bleaching of their eyes when looking into the sun). - Specialised Feeding o Manta rays – use cephalic lobes (big flaps of skin in the front of their head) can be moved to concentrate plankton, they also do somersaults to aggregate prey. o Sawfish – saw acts as antenna and can help locate prey. Also use saw as weapon, is not used on the bo om at all only used in mid water. - Forward Propulsion o Filter Feeding - Moving through the water column with very wide gape, common to basking shark, wale shark, and megamouth shark. These are passive feedings. o Streamlining – the skin of elasmobranch have den cles (small teeth distributed over skin) which can enable animal to move more freely through water, and also reduces damage. These den cles extend over skin on outside and to oropharyngeal to protect mouth and taste papillae (li le raised areas which  enable animals to make decision to ingest or spit out). Chimaerids and elephant sharks don’t have den cles. - Visual A rac on o Can be by lures, or by biofluorescence (these animals can absorb dominant high energy blue light and reemit it at a longer or lower energy wavelength – green, orange, or red part of the system). Sensory Capabili es - Neurobiology = study of the nervous system. - Ecology = study of the interac on of organisms and their environment. - The two together = neuroecology. - Sensory systems: o Hearing o Smell o Vision o Lateral Line o Electrorecep on o Touch o Taste o Magnetorecep on o Brain which receives this input - Senses are generally most effec ve over different distances (slide 31) - Neural Basis of Behaviour: o Singal – could be light could be odour or could be sound. o Propaga on o Sampling – must sample signal. o Transduc on – signal must be recognised and changed into signal central nervous system can recognise. o Summa on o Representa on o Processing o Behaviour Chondrichthyes (car laginous fishes) - Skeletons made of car lage, only teeth are calcified. - A lot of species rely heavily on electrorecep on. - Shark brain mass to body mass ra os are quite large. Osteichthyes (Bony Fishes) Shaun – lecture 2 Chemorecep on - Chemorecep on: Combina on of two different senses – taste and smell - Olfac on (Smell) o The oldest sense in animals, o en mostly involved in feeding and reproduc on. o Detects molecules in water. o Water is a slow carrier of olfactory signals. o Olfactory Plumes  Plume: effec vely the smell of something but in water which is emana ng from a par cular source.  All living things have some sort of organic source for chemoa rac on such as:  Waste products  Alarm signals  Death (necromones)  Elasmobranchs move their heads from side to side which allows them to move in and out of the high concentrated odour plume area which allows them to figure out the loca on of odour plume source.  The organ itself sits within the nostril and is a highly folded olfactory epithelium, it is highly folded so that the receptors are exposed to water as it comes into the nostrils. Receptors are able to respond to a wide range of odours. They have preferen al sensi vity to certain molecules based on diet. Primary pleats, and secondary folding to increase surface area for water to flood over.  Nasal Openings – bony fish: sits on dorsal por on of head, inhalant and exhalent nostril. Inhalant is slightly anterior to exhalent. Car laginous fish: ventrally located, a lot larger in size, don’t typically have an inhalant and exhalent.  Olfactory Currents: the water moving through the nostril can happen on its own by forward mo on, this happens in all car laginous fishes. In bony fishes there are direc onal mechanisms. Such as cilia (in isosmates) which beat and bring the water through to the ves bules. Accessory sac – an ac ve process which sucks in the water to the anterior nostril, water floods over the olfactory and then is squeezed out (this is called a cyclosmates).  Olfactory epithelium  Looks similar in most bony and car laginous fishes.  Sensi ve to food/prey, bile salts, amino acids, gonadal steroids, pheromones, and alarm cues.  Has sensory and non-sensory regions.  Receptor Cells: 2 major types o Villous o Ciliated  Suppor ng cells – long ciliated carpet of cells  Basal cells – more deeply located.   Goblet cells – exudes mucus over the membrane to keep it protected.  Olfactory input to the brain  Part of the brain dedicated to olfac on called the olfactory bulb. Size of this can vary largely.  The receptor cells terminate within the olfactory bulb organised into glomerular.  Define Mitral cells – make tree of nerve endings which then take this informa on to other parts of the brain via the olfactory tract.  Olfactory tract: lateral tract – holds informa on relevant to food odours, medial tract – holds informa on related to sexually relevant odours and other food odours. - Gusta on (Taste) o There are more taste buds in bony fishes than in any other animal. o Internal tastebuds found in oropharyngeal epithelium, basihyal, and gill arches. o Also, external taste buds found on the outer skin and barbels – this is only in bony fishes not car laginous fishes. o Taste buds are detec ng chemicals. o There are differences in taste bud density and distribu on which will relate to bite behaviour, food manipula on, and decision to ingest. o Taste Preferences  High gustatory sensi ve occurs in the detec on of noxious or toxic substances to animals.  External taste buds are important.  Factors influencing gusta on:  Level of hunger  Experience  Water temperature – can affect sensi vity of these receptors.  Pollutants  pH  Climate change o Taste buds:  Aggrega ons of taste receptors, occur on raised papillae or in small depressions.  Not all taste receptors are in groups of buds, single taste cells are receptors can be found. o Gustatory receptors  Capable of renewal, las ng between 12-42 days  Informa on is transmi ed to central nervous system by 3 of the cranial nerves (review to slides). All three project into the medulla.  Don’t know much about intraoral food segrega on. Light Detec on and Light Underwater - Signal is 400-700mn, at the surface of water animal are exposed to full visible spectrum. - Light a enua on – light intensity and the colour of water in different water bodies changes with depth. - Light available to deeper animals is restricted to blue and green. - Eye Diversity o Shape of eye, and shape of pupil can be quite variable. - Vision in Water o Hemispherical structure, living in water and has a protec ve goggle or cornea on the outside, inner part is predominantly filled by a spherical lens, the back part of the eye is the neural part of the re na. Light passes through the cornea, is focused by the lens onto a spot on the re na, that op cal image is transformed into a neural image which is then transferred to cells within the re na and that info is then moved along the re na into the op c nerve and op c never projects into the op cal centres of the brain. o Re na – completely transparent, has 3 predominant cell types, photoreceptors are in the back and are divided into rods and cones these absorb the light and by a process called phototransduc on the informa on is transferred into a neural signal travelling back the way it came going to the interneurons and then the ganglion cells which line the re na and the signals then travel up the ganglion cell axons along the inner part of the re na and exit the eye via the op c nerve. o Rods – rod-like, cylinder, pigment that absorb light sit in rows of disk, operate pre y well in dim light. o Cones – cone shaped, only operate in bright light. - Sensi vity to colour – photoreceptor sensi vity - Colour Vision in bright light o Need to be able discriminate colours by having at least two different cone photoreceptors both sensi ve to different parts of the light spectrum. o Discrimina on of objects. o True colour vision – is the detec on of colour not brightness. o There are 4 types of photoreceptors that operate in bright light. - Vision in fishes o In the ray there is 1 type of rod and three types of cones – almost iden cal to human colour vision system. o Black p shark – 1 rod and 1 cone, so this species is colour blind. Means that they aren’t using colour to differen ate prey but instead using contrast. - Visual cues to behaviour o Some rays are coloured, and their colour pa erns vary. - Pupillary apertures o Pupillary apertures: The gap within the iris which allows light to enter the eye. o In bony fishes the pupil of the eye is set and immobile and does not move in light or dark light o Elasmobranchs have mobile pupils. o Trade-off between large pupil for diffrac on limited vision and good light capture vs blurring due to op cal aberra ons. - Reflec ve Tapeta o Reflec ve tapeta: Mirror like structure behind the re na – responsible for characteris c eye shine of fishes, mammals, and invertebrates. Reflects light not absorbed by the photoreceptor back out through the photoreceptors and out of the eye.  o Occlusible – can close off the mirror. In light adapted version pigment covers mirrors and absorbs any light, not absorbed by photoreceptors – there is no reflec on. This inhibits deer in the headlights like sensa on. - Visual Acuity o Relates to the way an animal views its visual field. o The re na looks into its environment. If you take re na out and fla en in into a wholemount (diagrams), you can observe the density of photoreceptors and ganglion cells. o Area centralis – looking at visual field in front of the animal. o Visual streak (aka horizontal streak) – which extends all the way across the re na to give it a panoramic view to give it a higher visual acuity. Octavo-lateralis system - This is where the auditory and lateral line systems are combined (because the type of receptors that are giving rise to these systems are hair cells) - Both senses are divided, they use hair cells for the mechanotransduc on process. - Lateral line – its predominant is water movements. - Inner ear is effec ve sense organ to audi on and postural control. Later Line System - Can detect water movement and low frequency sound. - Used for feeding, schooling, predator avoidance, rheotaxis and obstacle detec on. - Rheotaxis: is the use of the lateral line system to sit in an oncoming current. - Most of their hair cells sit in canals, so water filled tubes under the skin. But there are also superficial ones which can sit in a pit in sharks or free on the skin in bony fishes. - Neuromasts = groups of hair cells that detect local accelera on of surrounding water rela ve to the animal. - Organisa on of Canals o These are unique to aqua c invertebrates. o Can be arrange singularly in pit organs or in groups in canals, or in lines in s ches. - Canal Neuromasts o 3 canals overhead, 1 over flank of body o They have pores. o Over each group of neuromasts is a gela nous dome called a cupula. It’s the water moving the cupula that ac vates the hair cells. Made possible by a bending of these hair cells. o Whether it is a free neuromast or a group of neuromasts, the movement of water along the canal provides an excitatory response or an inhibitory response. o Each hair cell has an orienta on. - Lateral line hair cell orienta on o Kinocilia o Movement towards the kinocilium (long one) is an excitatory response, movement away from the cilium is a towards the stereocilia (short one) and produces a inhibitory signal. Shaun – Lecture 3 What is Sound? - Some sort of mechanical disturbance to the water, generally a sound wave will be able to move through the water column in compressional and longitudinal waves. It needs a medium to move through – in aqua c environments this is water. Factors Influencing Sound Transmission 1. Absorp on – transforma on of acous c energy into heat energy. May decrease the intensity of the frequency of the sound wave. 2. Reflec on – will be abruptly reflected in different direc ons. 3. Refrac on – sound wave might enter a part of water that has high salinity where the density of water is different to another part. 4. Ambient Noise – will affect or mask sounds that could be cri cal for communica on. Grouping Sounds - Define Natural: produced by animals or by non-animals in events such as an earthquake. - Define Non-natural: Anthropogenic sounds such as tankers, shipping, airguns, sonar. Hearing Hearing Mechanisms in Fishes - Paired structures imbedded within the cranium, sits just towards the back of the brain on either side. - Otolith organs – main sound receptors. - Some mes the swim bladder and the ears are connected. - 3 semicircular canals in 3 different orienta ons. - Lagena, Saccule, Utricle – the otolith organs sit in these regions over a bed of hair cells, again imbedded in a cupula. The main parts of the cod ear - 3 semicircular canals. - 3 macula areas - 7 end organs – the three semicircular canals, the otolith organs, and macula neglecta (a 4th macula region where there are thought to be some hair cells) Saccular Otoliths - Define: White mass embedded within the ear is what we call otoliths, saccular otolith is the biggest. - In bony fishes they have somewhat bony otoliths. - Form growth rings which you can use to age the fish. - Chemical makeup of rings can show the areas of the ocean they have lived in throughout their lives. - Ear bones. Otolith Organs  - Otolith organs si ng over bundle of hair cells which are si ng within the cupula. When sound waves move through the whole head of the animal there is differen al movement of the otolith against the much lighter cupula and embedded hair cells, they move against each other. This differen al movement produces a mechanical movement of just the hair cells which enables the mechanical stresses on the hair cells to be transformed into a neural image. - Movement towards the kinocilium (long one) is an excitatory response, movement away from the cilium is a towards the stereocilia (short one) and produces a inhibitory signal. - Bony fishes have otolith. - Car laginous fishes do not have otoliths, instead they have many crystals embedded into a gela nous matrix known as the otoconial mass. You cannot use the otoconial mass to age a fish and there is no chemical composi on of the rings to look at. Hearing Sensi vity - Hearing generalists – good over a large range of frequency. - Hearing Specialist – specialise in a specific range of frequency. - Audiogram – a series of curves which will indicate what part of the hearing range a fish is able to hear in and what parts are most important. - Hair cell damage can occur from anthropogenic sounds such as airguns. There is some chance that these may regenerate with me. - Sensi vity to ultrasonic sound o Goldfish – generalist in rela vely low frequency o American Shad – is a generalist but has the developed the adapta on to detect ultrasonic clicks (predominantly of dolphins that use this to detect prey such as the American shad). They also have a pair of thin air-filled tubes which has increased sensi vity into ultrasonic range. Hearing in Sharks - Not much known in hearing in sharks. - Sensi ve predominantly to low frequencies. - They have small ear canals (bony fishes have no ear canals) found on the midline on the dorsal surface. - Don’t produce sound other than poten ally sound produced by muscle contrac on and ea ng of prey. - No swim bladder so cannot specialise their ear. - Good direc onal hearing. - Sound will affect lateral line system as they both rely on hair cells. Electrorecep on Define Electrorecep on: the ability to perceive electrical s muli from both ar ficial (anything that has an electric current in water, e.g., ba ery or boat engine) and biological sources. Passive and ac ve forms - Define Passive = what the elasmobranchs specialise in, the detec on of weak electric fields. Passive in sharks.  - Define Ac ve = Can be ac ve in par cular species of rays which produce their own electric fields. Elasmobranchs have the most sensi ve electrorecep on in nature – can detect 1 billionth of a volt. Electro sensory pore abundance varies greatly between species – this is dictated by how they use these pores. Ability of organs to detect and convey weak electric fields its detec ng is via a very highly conduc ve mucopolysaccharide gel which fills the canal and allows the strength of the electric field to be recognised. Anything producing electric current under water will affect behaviour of sharks. Passive electrorecep on Anatomy Surface Pores - Distribu on varies on a species-to-species basis. Pore abundance does not vary within a species, the number nor general arrangement does not change. - Hammer head has 2000 – 3000 pores. - Great white has 1000 – 2000 pores. - Wobbegong 300 – 1000 pores. - Horn shark 150 – 200 pores. - Shovel Nose Ray ~1000 pores. - Blue spo ed ray 700 – 1200 pores. - Pore abundance related to how species feeds and what it feeds on. Mechanisms of Electrorecep on - Occurs via Ampullae of Lorenzini - 6 or 7 ampullary organs with receptors around the edges of these organs. RC = receptor cells. SE = support cells. - Receptor cell is a hair cell-based system. Electrorecep on system can help an animal avoid preda on and can be ac ve in the egg case prior to hatching. When a poten al predator swims by it has evolved a way to hold its breath and reduce its electric field produced by ven la on. Human Influence on Electrorecep on - Anthropogenic ac vity via underwater ac vity which produce electric fields. - High risk that a lot of this ac vity can be detected by sharks. Magnetorecep on - Does exist in bees, crustaceans, and maybe turtles and sharks. - Sharks are sensi ve to magne c fields and may use the Earth’s magne c field for naviga on. - Some sharks have been known to swim in very straight lines in open oceans for long periods of me. - How are they likely to do it? o Use it to navigate long distances. o May be mediated by:  A photoreceptor-based system using cryptochromes which are proteins sensi ve to different wavelengths of light which is able to pick up magne c fields.  Or a magne te-based sensory system – so cells with magne c components  Or indirectly via the electro sensory system in two possible ways:  1 – electric currents induced by sharks’ own movement through the earth’s magne c field.  2 – electric currents are induced by the mo on of the ocean stream through the earth’s magne c field. Trav – Lecture 1 Metabolic scope in teleost fish (true bony fish, not sharks and rays). Intended Learning Outcomes: 1. Understand the importance of muscle in rela on to fish biology. 2. Appreciate how an understanding of fish biology can be used for conserva on management, food produc on, animal welfare etc. Metabolism: - Metabolism: the net process of all the chemical reac ons occurring within living cells, and these reac ons are necessary for the maintenance of life. - Metabolic rate: the rate at which these processes occur. Star ng at basal (res ng) level but are then able to accelerate. - Metabolic Scope: the range at which these processes can occur. Teleost (bony) Fish - Fish are the most diverse set of vertebrates on the planet, with ~33,600 species. - They have many different habitats, a whole range of life strategies, sizes, and shapes. These factors all play a drama c role on metabolic requirements. - 2 broad categories: 1. Sedentary species – species that don’t move far from their home range, moving a long distance may incur a risk of preda on. 2. Migratory species – ones that may migrate over a dal, seasonal, or yearly cycle. Muscle - Muscle makes up the bulk of ssue of most teleost shallow species. - E.g., moray eel is quite strong, tough, muscular, and flexible. Contrasted to gulper eel that lives in deep water there are vast differences. The gulper eel has a hinged jaw and collapsible stomach being able to consume prey items 20x bigger than its actual size. - Deep water is a low produc on habitat with not much food available so you do not want to expend energy needlessly, if deep sea animals had lots of muscle, they would need to feed a lot (would require a lot of energy for all these muscles). In reality deep sea creatures are opportunis c and can’t feed that o en so will have reduced musculature. - Muscle in fish is characterised typically as white or red based on colour: o These muscles differ widely in physiological and metabolic proper es. o Red muscle – on image see below (Australian Salmon) is near fins. o Most fish swim in serpen ne manner. White muscle is distributed predominantly along the spine so when the animal needs to swim faster or use more force  white muscle is invoked, when the animal is cruising in an ordinary way the red muscle is used to steer and control movement. o Red Muscle: Type 1 muscle or slow muscle. Has a high oxygen demand as it has oxida ve fibres. It has this high demand because consuming oxygen and glucose produces ATP which is the cellular energy required to power a cell. Has lots of capillaries to be able to deliver oxygen. Has myoglobin made from iron to carry oxygen, this iron makes the muscle appear red. They have more mitochondria to produce more ATP. o White Muscle: Type 2 muscle or fast muscle. High in glycoly c capacity, has lots of glucose stored within the muscle. Works well without oxygen but isn’t very efficient at producing ATP. Good at contrac ng and producing quicker force. o In most fish 90% or more of the muscle mass is composed of white muscle o Tuna has predominantly red muscle, they need to swim a minimum of 1 body length per second or will suffocate. If they stop swimming, they wouldn’t be able to supply muscles with enough oxygen. They even swim whilst sleeping. o Stargazer/Monk Fish = almost en rely white muscle, dorsoventrally compressed, ambush predator, has to explode and capture prey quickly so needs to able to move quickly. Otherwise, when not capturing prey will sit and wait. o Australian Salmon = dal migrator, high percentage of white muscle with some red muscle off to the sides. Ac vely swimming several kms per day, moving in and out with the de. Grow to about 5kg, so can be eaten and need to be able to accelerate away from predators, but also accelerate to catch prey like bait fish. - Sedentary fish species o Virtually contain all white muscle. o Don’t need to swim long distances just need to be able to ambush prey. o Not under any selec ve pressure to have any red/oxida ve muscles. o They u lize less oxygen than migratory fish. - Migratory Fish Species o Swim long distances either in response to dal fluctua ons, searching for food, or for reproduc on. o Require endurances and so have 10-30% of red muscles. - Limita ons to Metabolism o Temperature – bony fish are ectothermic, so ambient temperature will dictate body temp. If you increase the temperature the reac ons happen faster.  Short term changes – changes with de and me or day when colder oceanic water is rushed into shallow water. The de changes every 6 hours.  Long term changes – due to not only seasons but also factors such as climate change.  Increasing temp leads to a decrease in the oxygen carrying capacity of seawater. Hot water contains less oxygen than cold water.  Decrease oxygen.  Consequence for fish – if water heats up, body temp increases, which increases metabolic rate, which increases oxygen demand. As a result, fish presume they should increase their growth and body size.  BUT increase temp = increase acidity of water. Decrease of pH has two key effects on organisms:  1. Decrease the oxygen carrying capacity of seawater. 2. Decreases the gills’ ability to exchange oxygen. ^both of these cause big changes in metabolism of fish which can stunt growth.  Body mass plateaus with ages – temperature-size rules  Temp vs growth: pejus = term derived for where life can occur buts it’s in danger, pssimum = where life is not sustainable. Typically, bell-shaped curve for fish. o If it’s cold the growth rate is slower as metabolic rate is slowed. o Extend beyond point of maximum growth there are declines in growth, lifespan, and reproduc on resul ng in fewer and smaller fish. o By the end of the century, it will be a decay because the window for growth and life will be reduced to only 10c. o If there is a spike and no cooler water to move to behaviour thermoregula on is limited. o pH – important for oxygen carrying capacity and discharge of oxygen across the gills for respira on. o Dissolved oxygen content – in the air there is a lot more oxygen available then there is in sea water (see slide). Poten ally what is driving the abundance of cleaner fish that keep respiratory surfaces clean. 130 species of cleaner organisms.  Hard to quan fy the dissolved oxygen in reef flats or tropical reefs (refer to slide 20 for reasons why)  In low current flow you get temperature gradients created. In high current flow this is reduced.  Stra fica on: is where you get different temperature layers forming in a body of water with not much mixing between the two. o Behaviour and physiology  Avoiding predators – animal may have to tolerate an unfavourable condi on then to increase the risks of preda on. BEHAVIOUR.  Certain food resources might only become available at certain mes meaning you may have to travel long distances and burn energy but then you will get energy back from food. BEHAVIOUR.  Muscle fibre types. PHYSIOLOGY  Type of diges on – both herbivores and predatory fish. PHYSIOLOGY o Shape and Size  As you increase size of object the surface area rela ve to volume has lowered, so if that decreases it lowers the metabolic rate.  If you increase surface area rela ve to volume it increases heat gain and loss.  Spherical animal = reduced surface area to volume, rela ve to laterally compressed animal.  Most small larval stages start to develop in the warmer months and the shape helps them to take on heat so they have faster metabolism and can grow faster. - Fish Kills o Define: Where you have a large biomass of fish in restricted volume of water, so there is an increase in oxygen demand, having this increase will then cause oxygen deple on which can then cause a catastrophic collapse. They either all have enough oxygen, or they all don’t. o This can be cause by a lot of things such as bad weather. o Blackwater Events  Typically happen in freshwater environments causing a transient hypoxic event (short loss of oxygen)  Bush fires – a lot of carbon content liberated, and a rainfall event causes the ash to enter the water way and bind in water.  Blue-green algae blooms Travis – Lecture 2 Bivalves belong to class Bivalvia and form of mollusc from phylum Mollusca. Abundance and Diversity: - 93 thousand species of molluscs. - Represent ¼ of all marine organisms or 23%. - 2nd only to arthropods. - Cons tute 80% of coral reef diversity. - Bivalves can be found in marine and freshwater environments. - Class Bivalves have 2 valves with a hinge element that holds the two together – a form of mollusc which has lost its radula and converted that into instead being filter feeders. - 2 types of bivalve’s molluscs: 1. Epifaunal (sessile)  Usually a ach themselves with strong byssal filament. This byssal material is some of the toughest material to occur in the natural world. Would be easily dislodged if they didn’t have some mechanism to strongly a ach to rocks.  Can have enormous biomass of these animals. They can form aggrega ons (also known as beds). Is the dominant species in terms of biomass in par cular animals.  Adapta on to risks:  Dog whelk feeds on mussels by using radula to grind through the shell. Preda on in the animal kingdom o en between closely related animals. What the mussel can do with Bissel filaments is a ach them to the dog whelk so its unable to escape and eat other mussels, so it then dies. 2. Infaunal (free swimming) Zona on and Associated Risks - Suscep ble to desicca on in high de area if they cannot move away. o The higher up you are the longer the period you are out of water for. o Scallops have the advantage to move – either horizontally to get to deeper water, or by burrowing down to find the water column. - Beneath low de is always covered in some degree of water. o Greatest risk to giant clams is preda on by other gastropods. Avoidance or Risk Management - To reduce risk of desicca on oysters must completely seal and make their shell water ght. - Scallops have delicate nervous systems to detect movement from predators and swim away or burrow down. They move via jet propulsion. - Giant clam – will close up par ally if at risk of preda on and retract mantle. They will close further if at further threat. They cannot close completely as if they did, they would produce carbon dioxide and metabolically poison themselves. They can only close 90% of the way. They can also jet water out to try and startle predators. Physiology of the ‘Catch’ Mechanism - ATP = cellular energy, when you contract a muscle, you are using up ATP. - Bivalves can contract and stay contracted producing high levels of tension for hours upon end with virtually no energy use. No other animal can do this. - Catch mechanism can be found in smooth muscle and a unique variant of striated muscle. - Only tonic contrac ons count as catch. - All molluscs have a donut shaped brain – the oesophagus goes through their brain. The pedal ganglia (neural network – no brain) secrete neurotransmi er molecules which cause contrac on which can be either aphasic or transient or a tonic or colom sustained contrac on. o Aphasic: contract and then relax. o Transient: --- o Phasic: quick or rapid response (slide 27, rapid contrac on). o Tonic: persistent contrac on. o Colom: --- - Scallops’ ac ve swimmer – have a rela vely large adductor muscle which is made up of two types of muscle. Smooth muscle, which is opaque and white, if they need to maintain the shell closed or tonic for a long period of me, they will use this muscle. Striated muscle, which is yellow and translucent, they will use these muscles if they need to swim away, produces phasic contrac ons. Cerebral ganglia = primi ve brain. - Contrac on is produced when myosin forms cross-bridges, it is thought that these animals had paramyosin that had hooks and they thought these hooks slid over each other and hooked in so the muscle didn’t have to keep suing force or ATP – this has since be debunked. - More recently thought to be a type of rigor mor s. - Pathways: o Contrac on is caused by a build-up of intracellular calcium. Can raise this in two ways:  Release calcium from internal stores – diagram 1 page 20.  Bring in calcium from outside the cell – diagram 2 page 20. o Serotonin causes a reduc on in intracellular calcium. o Myofibrils: proteins associated with contrac on. o Seawater has lots of calcium in it. o G-protein = light switch for sequence of events. 16 known g-proteins. o Receptors are bound to different g-proteins. o Image 1 (page 20) = internal store of calcium is yellow sphere. o Dephosphoryla on = the removal of a phosphate group which is a ached to a protein. Dephosphoryla on of the twitchin molecule leads to catch. Phosphoryla on of twitchin releases catch do this using serotonin. o Direct current = no change (DC) current. Only acetol colleen released (ACH). o Alterna ng current = apply current, no current, apply current. Releases ACH (causes Catch) and serotonin (causes relaxa on), so you get phasic response. This is not catch as both are being released. o Recover from heat damage by chaperone proteins to repair any damage. o Catch response in a giant clam does not produce it to the same degree as first example of prac. Would poison itself metabolically is it did this.  o Swimming Scallop – nocturnal. If it can’t avoid predators by swimming or burrowing it can s ll go into catch. Consequences of Climate Change - A rise in temperature and a rise in acidifica on (change in pH). They alter basal rates and many other things that will cause issues for bivalves. Travis – Lecture 3 Need water for life – it is a fundamental factor that needs to be controlled and available. This can create struggles for places where freely available water is limited – such as arid and polar loca ons, and heron island (has no freestanding water). Can humans drink sea water? - No, sea water contains 3.5% salt, and the mammalian kidney can only sustain salt up to 2%. Mammalian Kidney - Nefron – func onal unit of a kidney. The minute or microscope structural and func onal unit of the kidney. - Arcuate artery delivering blood flow into kidney, blood then passes into bowman’s capsule (a part of the nephron that forms a cup-like sack surrounding the glomerulus) and there are arterials that branch off there (vascularized area known as the glomerulus), the loop of Henle is where water is absorbed back into the body and salt is concentrated here. How do Humans Survive on Heron? - Define Osmosis = the movement of water in the direc on of where the highest salt concentra on is. - Desalina on plant on heron which does reverse osmosis. Osmosis - Osmosis: the movement of a solvent (water) across a semi or selec vely permeable membrane. - It is a passive process. - Think of it as trying to dilute the salt and make it less. - If something freely moves across a membrane (like ethanol) it is not an osmo cally ac ve par cle. - Refer to par cles as osmo cally ac ve par cle – add up all these par cles and we refer to that as osmo c concentra on / osmolarity. - Osmosis will con nue to occur un l an equilibrium is reached. - Isotonic = equal (cells within the bony fish are the same as water). - Hypotonic = salt concentra on of the water is lower than the salt concentra on in the animal. - Hypertonic = salt concentra on of the water is higher than the salt concentra on in the animal. Diffusion - Diffusion: Solutes will move and distribute evenly throughout the solu on, they do so to minimize the concentra on of solute. - The is a passive process. How to Marine Coastal Organisms Cope - The Sea  o Biggest piece of evidence for evolu on beginning sea is that our cells are made up of the same ions as the sea. o 71% of the Earths surface is covered in seawater. o Thermal capacity – means it retains heat. - The Li oral Zone o May be inundated by freshwater which can dilute the water. o Tidal pools might be exposed for several hours, meaning the de pools might become diluted due to rainfall, or more concentrated if you have baking sun and water is evapora ng. o Estuaries have a gradient. o Most animals in brackish waters are euryhaline Osmo conformers. o Water moves in faster than salts move out. o Stenohaline osmoconformers – have a strict narrow osmo c concentra on they can tolerate, when they are exposed to an osmo c insult their cells can swell and stay swelled. E.g., goldfish, sea turtle, haddock o Osmoregulators have the ability to regulate cell volume and this is a cri cal part of their strategy. - Pa erns o Stenohaline: see above. o Define Euryhaline – tolerate large expansive changes in salinity, might be something like a salmon or bull shark. o Define Osmoconformers – there ssues tolerate large changes in internal environment. o Osomoregulators – all terrestrial animals, sea turtles, and true bony fish.  1. Hypo-osmo c – slightly below surrounding medium.  2. Hyperosmo c – slightly above the surrounding medium. o Some animals have the ability to do both osmoconformer and osmoregulatory behaviourally. o Osmoregulators are all terrestrial vertebrates o - Hagfish & Invertebrates  o Have high water permeability between cells so forced osmoconformer, therefore have a high tolerance for changes in salinity. o There cells are isotonic ensuring no net loss of water. - Bony Fish o Ac vely drink water, they also do so accidently when ea ng. o They excrete really concentrated urine. o Can also ac vely excrete salt via the gills. o Freshwater fish – urinate large volume. o Saltwater fish – urinate small volumes. - Elasmobranchs o Osomoconformers but ion-regulates. o Once digested a meal urea is produced. 1 molecule of urea breaks down to form two molecules of ammonia. o Urea is in the blood. o Trimethyl amine oxide is in the blood. o Keeping internal ssues slightly hyperosmo c to reduce water loss. o Glomeruli – reabsorbs the urea. Reabsorbing urea and making TMAO on there blood. Blood flows into bowman’s capsule where it recycles the parts needed to make TMAO. Animals can change the size of proteins passed through. o Sharks produce large volume of hypertonic urine and have a modified kidney to help with that. o Offset the difference between the outside and their internal environment by producing nitrogenous waste products a er undergoing diges on. They do this in the form of urea (2 ammonias) and reabsorb this, this means they retain ions which decreases the amount of water going out. - Rep les, Mammals, Birds o All have terrestrial or freshwater origins. o Osmoregulators. o No diffusion of salts across gills or skin. o Tend to lose water and gain salt. o Mammals: most of the salt reduce by the kidneys, producing hyperosmo c urine. o Rep les & Birds: have salt glands which are similar to the rectal glands in elasmobranchs. o Birds: paired nasal salt glands just above beak which produces highly concentrated salt secre on o Water Birds (Behavioural)  Some water birds can behaviourally regulate their salt such as pelicans.  They obtain all required water from their diet.  Pelicans can eat up to 4kg of food per day.  Birds can be highly selec ve on what they eat, avoiding ea ng osmoconformers and instead ea ng osmoregulators. o Seabirds  Incidentally swallow seawater when ea ng.  Birds’ kidneys lack a loop of Henley (this is where water can be absorbed), so they can’t use their kidneys to get rid of salt.   Instead, they have developed a nasal salt gland – an artery brings blood into nasal salt gland and salt is pumped into collec ng duct and then goes out the duct and down the nose.  Aquaporin is a protein.  Hydra on pathways  Nasal salt glands  Watery diet o Silvereyes behaviourally select items which are high in water.  Produce metabolic water. o Can load up body with fat and then break it down using beta oxida on reac on, by products of this are carbon dioxide and water. o Sea Turtles  They eat jellyfish which are osmoconfromers, and jelly fish are about 95% water.  Kidneys have limited abili es to increase salt concentra on.  Excrete salt via air of specialised nasal salt gland.  Lachrymal salt glands  Sits directly behind olfactory sac.  Leatherback turtle  Throat lined with chiton based spiked.  World’s largest oesophagus in rela on to body size.  Eats its own body weight in jellyfish each day.  Thick blubber layer like whale (they eat jellyfish which are 1km down, so they have to dive) because it is cold diving down, so they have an insula on layer.  Have these backwards slan ng spikes which stop the jellyfish from ever flowing back out. They will contract oesophagus to eject water out, but the jellyfish are stuck. o Other marine rep les  Some feed on sea grass such as marine iguanas.  When ea ng the sea grass, they are taking in lots of salt, they also have specialised cranial glands they can use to excrete salt. They can pressurize these glands and expel it with force. o Crocodiles and Alligators  Similar salt glands to turtles but they are lining the mouth and are not nasal but lingual salt glands (in crocodiles, the salt-excre ng glands are located on the tongue immediately below the lingual epithelium). o Sea Snakes  Pterygoid walk – they walk their jaw over their prey by doing this they reduce how much water they digest.  They have flexible oesophagus’ that pokes out to the side.  These don’t take on a very high salt load.  Usually eat teleost fish – can avoid losing water by ea ng teleost regulator fish. Kerry – Lecture 1 Behavioural Endocrinology - Hormone: a chemical substance secreted by a gland in one part of the body that travels through the bloodstream to produce an effect on target cells or organs in another part of the body. o Throughout your body there are endocrine cells, which are specialised cells that produce chemical messengers and then secrete these messengers into the blood stream which are then carried throughout your blood stream un l they reach the target cell. They know when they have reached the target cell because there are special receptors in the cell that will grab the hormones when they pass by. Once the hormones bind to the receptors it triggers a response. - Endocrine system: Endocrine organs sca ered throughout body. They communicate by sending chemical messengers and sending them through the circulatory system. - Nervous system: coordinated by the brain and comprised of a complex network of neural cells communica ng by sending electrical systems. - - Animal communica on: o Endocrinology is a large component of animal behaviour. o Generally, have a signaller (some individual who is elici ng some kind of signal), and you have a receiver who will receive that message and may or may not respond. o Hormones can affect:  Probability of performing a behaviour – probabilis c model. E.g., testosterone: higher levels of this associated with higher levels of aggression, but all individuals with high testosterone aren’t being aggressive all the me. It increases the probability but is not a switch.  Signal produc on – visual, chemical, or auditory signal.  Signal percep on – if they respond to it or ignore it etc.  Response to signal – behaviour in response to the signal. o Effectors = motor neurons. o Hormones influence every level of behaviour. - Examples: o Lantern Shark Bioluminescence:  They have spines that glow. Blue/green belly light allows camouflage. Sides light up to coordinate movement.  What are the func ons of these bioluminescence signals (all groups of sharks that can do this)?   Biggest reason seems to be camouflage – sugges ng its an important an predator behaviour  How are these bioluminescent signals controlled?  Have specialised li le pockets that include photocytes that produce the pigment that oxidizes then produces bioluminescence. Lined at bo om of pit with special cells that act as reflectors. Iris like structure at bo om of the pit that can close off or open up to allow less or more bioluminescence.  What’s controlling iris like structure? o Neural control? – to figure this out they exposed skin to a number of different typical neurotransmi ers (adrenalin, noradrenalin, serotonin) this caused no response or change. o Endocrine control? – to test this they did the same thing, exposing them to different hormones. When they exposed it to melatonin the iris like structure opened resul ng in more bioluminescence. Other two hormones caused iris structure to close down = less bioluminescence.  If skin is responding to melatonin than there must be melatonin receptors there. There is a signal cascade when the melatonin binds to the melatonin receptor with the result being it causes the iris to open by making the black pigment aggregate to edge or iris. o Plainfin Midshipman Communica on  Bioluminescence on ventral side.  Lives in the deep ocean for most of the year. Then in spring during breeding season they migrate right up into the inter dal zone.  Males vibrate swim bladders to produce sound – either to a ract females or as warning. Once they have a racted females they mate and a ach eggs to the underside of rocks covering them and the male will  stay there to guard the eggs to take care of them, protect them, and circulate water around them.  Their sound is so loud because there can be a lot of males in one area.  Gravid females (females with eggs le to lay) will respond to singing.  A spent female (female who has laid all of her eggs) will ignore singing.  Are there differences in hearing?  To explore this, they a ached fish to electrodes and played them different sounds and recorded their neural responses. This showed that reproduc ve females were much more sensi ve to changes in sounds as opposed to non-reproduc ve females.  What causes the differences in hearing? o Complex inner ear. o Reproduc ve females have a hair cell density at a much greater levels (both large hair cell bundles and smaller hair cell bundles) than non-reproduc ve females.  What causes changes in hair cells? o Estradiol (estrogen) increases during breeding season. o Estradiol receptors in inner ear of fish can explain these changes. o When estradiol binds to estradiol receptors it causes confirma onal changes in hair cell that produce more of the BK channels which play a role in transmi ng that message to the nervous system. The more of these channels the more sensi ve the hair cell is to sound. - Types of Hormones: o Protein Hormones  Formed from amino acids – typically DNA to RNA to protein chain of events is how you get all protein-based hormones.  Have giant pro-hormone. This is then chopped and fragmented. Middle sec on of POMC gene becomes ACTH which is one of the hormones that causes iris to close.  They have receptors on the surface of the target cell.  They elicit response from target cell by ac va ng secondary messengers.  These generally result is fast but transient effects.  Everyone has different proteins.  Recycled. o Steroid Hormones  Derived from cholesterol.  Cholesterol is always the same.  Progestogen – thought of as pregnancy hormones.  Glucocor coids – include cor sol and cor costerone are the main hormones thought of in this sec on. O en considered stress hormones  Androgens – include testosterone and dihydrotestosterone – o en classified as male hormones.  Estrogen – includes estradiol but there are a few extra.  Steroid biosynthesis pathway – is a one-way path.   Receptors in cytoplasm – so the steroids have to get to target cell and across membrane before it can have effect. They diffuse easily across membranes so they can move in and out easily.  Once bound to receptor it migrates into the nucleus and binds to the DNA causing changes in gene expression. The ul mate effect of this is that is has slower effects of longer dura on.  Excreted. Kerry – Lecture 2 Popula on demographics – changes in popula on sizes, birth rates, death rates etc. This can take a long me, meaning our understand of impacts on animals can be a bit behind. There has now been a shi to using individual physiology as an indicator of popula on health. To also understand how environmental condi ons impact an individual’s physiology. Endocrine Biomarkers 1. Reproduc on – there are a number of things that can be used to understand reproduc ve health of individual or popula ons. 2. Stress – can be a useful way to see how animals perceive their environments and how they respond to change but can be difficult to understand data because you have to separate out normal ac ons and stress induced reac ons. North Atlan c Right Whale - Numbers have taken hard hit due to hun ng. - Popula on had been increasing but recently has been declining again. - In comparison to southern right whale the increase seen in northern right whale is not very good. - Hormones by defini on are in the blood – how do you get blood sample from an animal like this? o Instead of collec ng blood you collect whale poo which also holds many of the hormones that can be used to answer same ques ons.  From this poo you can determine the ra o of males to females.  Look at sexual maturity – how many in popula on are adults and juveniles.  How many females in popula on are pregnant. o How do you find whale poo?  Dogs can sniff out poo.  This technique was first used for right whales but has since been expanded to other whale species. o How are there hormones in poo?  Steroid hormones are excreted into other substrates.  Protein hormones can be recycled. Protein based hormones are sensi ve and not stable and degrade quickly so harder to monitor.  Steroid hormones, star ng with cholesterol, are a one-way path. Once the hormone is released the body can’t do anything else with them.  Steroid hormones get picked up by target organs and exert effect, but if they aren’t picked up then they get picked up by the liver which will process and get rid of them as the body can’t reuse them. Once the liver tags them for excre on they get directed and incorporated into urine in the kidneys, or they get directed and incorporated into bile in the large intes ne and excreted in faeces. There are quite high levels of steroid hormones in both faeces and urine. o Advantages of non-invasive hormone monitoring:  In contrast to blood sampling there is minimal impact on animal.  Allows for longitudinal monitoring – the level of hormone isn’t as important as the pa ern.  Provides integrated measure for what is occurring.  Urine provides a broader measure – showing smoother overall picture of what is happening.  Faeces is an even broader picture.  Hair shows a really long- me frame which in some ways can make it more difficult to use.  *There is also a lag me – serum tells you what is happening at the exact me. Saliva a couple minutes ago. Serum 12 – 24 hours ago. Faeces 12 – 48 hours ago. Hair tells you what was happening quite a while ago depending where you are looking on the hair sha.  Researchers are looking for more non-invasive ways to monitor.  Collec ng whale blow (saliva snot mucus type thing).  Look at baleen on whale carcass – notching every cen metre to show changes over me.  Eggshells or egg yolk – found there were different hormones in the loggerhead eggshells depending on gender of turtle using shell. Reproduc ve Endocrinology - At the core of reproduc ve endocrinology is the HPG axis (hypothalamus, pituitary, gonads axis). This is a chain of command that shapes everything about reproduc ve endocrinology. - There are a number of cues that are detected by brain (food and resource availability, social cues, temp cues, photoperiod etc.). The brain will ac vate HPG axis upon receiving these cues. The hypothalamus will release GnRH (gonadotropin releasing hormone – related to gonads). This s mulates anterior pituitary gland to release LH (luteinising hormone) and FSH (follicle s mula ng hormone) these both acts on both ovaries and testes to drive important changes par cularly with regards to the gametes (release of eggs in the ovary and sperm in testes), also drive hormone produc on in gonads (testes = testosterone, ovaries = estrogen & progesterone). - By being able to monitor these three hormones we can monitor seasonality. - Throughout the ovarian cycle estradiol and progesterone fluctuate in different ways – this can tell you if the female is reproduc vely mature, is she in a breeding season, is she ovula ng normally, how long are the cycles, how frequently does she ovulate. If female becomes pregnant then you can see progesterone levels increase. - Hormone monitoring can indicate: o When does reproduc ve maturity occur. o When/how long the breeding season is. o Dura on of reproduc ve cycles. o Is a female pregnant. o Any abnormali es with ovarian func on or pregnancy. Kerry – Lecture 3 Humans have a rela vely large impact on the ocean. HPA Axis - Hypothalamic Pituitary Adrenal axis - Adrenal glands – two triangle glands si ng right on top of the kidneys. - When the brain receives s mulus that ac ves hypothalamus to release cor cotrophin releasing hormone (CHR) this travels to the anterior pituitary which then releases adrenocor cotrophin hormone (ACTH). This travels to adrenal glands. In the centre of adrenal gland is li le zone that specialised in producing glucocor coids. Main ones of these are cor sol and cor costerone. - Glucocor coids are not synonymous with stress. o Ini ally named for their role in glucose. o They play important role in circadian rhythm. They show increases at the beginning of the ac ve phase and then decrease throughout the rest of the ac ve phase. They s mulate arousal pathways to get your body ready for the day. o Responsive to light signals. o They change seasonally.  o They respond to metabolic demands – increase a er ea ng. o Growing evidence that they play important role in influencing reproduc on. Increases in them are necessary for healthy reproduc on in a lot of cases. They are highest during breeding season. o Immune func on – an -inflammatory so they help suppress immune responses. o Acute stress – when animals are exposed to acute stressors there is an increase in GC’s. o GC Physiology:  Bind to receptors then migrate into nucleus where they bind to GC response element. That then ac vates a response that influences gene expression in nearby genes. Can increase or decrease gene expression.  Types of Genes being impacted by GC:  Glucose transporters – energy regula on is func on.  Clock genes – circadian rhythm is func on.  Immune genes – inflamma on is func on.  Co-ac vators – all these molecules come together, and which genes will get upregulated or down regulated will depend on which co-ac vators are present. There are also different types of GC receptors – several differences in what these receptors look like which can also impact which genes are regulated.  GC’s can regulate 20% of the genome – ~6000 genes.  Effects of GC’s can differ by cell type. Whale Response to Boat Ac vity - North Atlan c right whale - Boats elicit a lot of low frequency sounds – these can interfere with vocal communica ons, can affect percep on of environment, can also just put animals on edge. - Researchers monitoring these whales around New England – got samples before and a er 9/11. A er 9/11 they closed the harbour for long period of me and it was quiet in the water. With the quiet me the GC’s were significantly lower when boat signals were eliminated. Endocrine Disrupters - Endocrine disrupters: Chemicals that can be natural or synthe c that mimic or interfere with the body’s hormones. - Includes plas cs, flame retardants, toothpaste & shampoo, pes cides, cosme cs, drugs (human medicine) including reproduc ve medica on like birth control pill. - Endocrine disrupter is a molecule that’s also able to bind to hormone receptors. o Disruptors that bind to receptor and cause a similar response – these are called agonists. This can lead to response being expressed at the wrong me. o Super-agonists – bind to receptor and cause response but really good at doing it so cause exaggerated response that can be a bigger response than it’s supposed to be. This can ini ate nega ve feedback that then suppresses the whole thing for longer so that you can’t get a response even when you are supposed to.  oAntagonists – bind to receptor but don’t have effect, so they essen ally just block it and stop the natural hormone from binding. - Two main cell types in tes s o Leydig cells: these cells act as the primary source of testosterone. o Sertoli cells: to nourish developing sperm cells through the stages of spermatogenesis. o Endocrine disruptors can interfere with this pathway at every single level which results in decrease of reproduc ve success and/or func on. - Sand Goby o Found high levels of estrogenic compounds (things that mimic estrogen) o When the males were exposed to effluent it reduced their tes s development and effected reproduc ve behaviours so weren’t ac ng like a male should act o Also cause males to start to undergo vitellogenesis which is the produc on of yolk. - So many subtle varia ons on what these disrupters look like that its difficult to study them. - Addi onally, these o en get studied in ar ficial se ngs so hard to extrapolate what that means to the whole animal. Light Pollu on - Light cycles affect: