Fish Biology: Anatomy and Physiology Review Class 2023 PDF

“Fisheries Professional Licensure Examination Review Class 2023” Fish Biology: Anatomy and Physiology NICO JOSE S. LEANDER Regional Fisheries Research and Development Center Bureau of Fisheries and Aquatic Resources 3 College of Fisheries Central Luzon State University August 20, 2023 Presentati...

“Fisheries Professional Licensure Examination Review Class 2023” Fish Biology: Anatomy and Physiology NICO JOSE S. LEANDER Regional Fisheries Research and Development Center Bureau of Fisheries and Aquatic Resources 3 College of Fisheries Central Luzon State University August 20, 2023 Presentation Outline I. Anatomy and Physiology: - What is a fish? - Form - Function What is a fish? Etymology: Dictionary entry *peysḱ- Language Definition Proto-Indo-European (ine- pro) *h₂ep- Proto-Indo-European (ine- pro) *pisḱ- Proto-Indo-European (ine- pro) *fiskaz Proto-Germanic (gem-pro) Fish fisc Old English (ca. 4501100) (ang) Fish *fiskōną Proto-Germanic (gem-pro) To fish, to catch fish fiscian Old English (ca. 4501100) (ang) To fish fish English (eng) To hunt fish or other aquatic animals Traditional definition of fish •Old English: "any animal that lives entirely in the water“ Old English definition of fish once had a much broader usage than its current biological meaning. Names such starfish, jellyfish, shellfish and cuttlefish attest to almost any fully aquatic animal once being fish. Defining a fish is difficult because the term fish includes a very wide range of aquatic animals Of the nearly 50,000 species of animals with backbones, approximately 4,500 are mammals, 9,700 are birds, 6,500 are reptiles, 4,000 are amphibians, and 25,000 are fishes. What makes a fish a fish? Accepted and valid definition of fish: • a poikilothermic, aquatic chordate with appendages (when present) developed as fins, whose chief respiratory organs are gills and whose body is usually covered with scales” (Berra 2001) • an aquatic vertebrate with gills and with limbs in the shape of fins (Nelson 2006) Important note! • Definitions are dangerous, since exceptions are often viewed as falsifications of the statement (Berra 2001). • Exceptions to the definitions do not negate them but instead give clues to adaptations arising from particularly powerful selection pressures. • Thus, deviation from “normal” and other exceptions are part of the lesson that fishes have to teach us about evolutionary processes. Terms and definitions of words used to describe fish Term Poikilothermic Opah, the first warm-blooded fish Definition An animal whose temperature adjusts with the outside temperature. These kind of animals have historically been called coldblooded, but that is not completely accurate. If it is cold outside, their body temperature will be cold. If it is warm, their body temperature will be warmer. Most fish are poikilothermic, but some fish, like tunas and lamind sharks, use special blood vessel networks to keep their body temperature warmer than the surrounding water. This helps them to be better hunters. Terms and definitions of words used to describe fish Term Definition Aquatic Living in the water, either seawater or freshwater. Some fishes like lungfish or mudskippers may be able to spend some time out of the water, but they cannot remain permanently out of the water, and they are confined to wet areas. Mudskipper Blenniidae Terms and definitions of words used to describe fish Term Chordate Definition Animals with notochords. A notochord is a stiff rod of cartilage that supports the nerve cord. Chordates have some other features in common, like gill slits, and a dorsal nerve cord. Mammals, birds, reptiles, amphibians, and fish are all chordates, a few invertebrates are chordates too. An animal that has, for at least some stages of its life, a dorsal hollow nerve cord, a notochord, pharyngeal pouches and muscular tail Terms and definitions of words used to describe fish Term Definition Organs for gas exchange. Most fishes breathe with gills. Gills However, some fishes have lungs, some can exchange gas through their skins, and some are able to gulp air and exchange gas through their stomachs. Gills are responsible for a number of critical functions like respiration, osmoregulation, excretion of nitrogenous waste, pH regulation and hormone production. Terms and definitions of words used to describe fish Functions of fish scale: Term Definition • Protection: external protection of the Thin plates that cover the thin skin fish from the environment (predators, of fish. Modifications of scales include hard bony plates or spines. parasites and injuries) Scales can also be very small or Scales • Hydrodynamic purpose: multiple, absent in some fishes, like blennies or eels. overlapping scales provide flexible covering that reduces friction with the water, allowing the fish to move easily • Placoid scales are found in the sharks and rays. Placoid scales are made of a flattened base with a spine protruding towards the rear of the fish. These scales are often called dermal denticles because they are made from dentin and enamel, which is similar to the material teeth are made of. • Ganoid scales are flat and do not overlap very much on the body of the fish. They are found on gars and paddlefishes. In the sturgeon, ganoid scales are modified into body plates called scutes. • Cycloid and Ctenoid scales are found in the vast majority of bony fishes. These types of scales can overlap like shingles on a roof, which gives more flexibility to the fish. These scales also form growth rings like trees that can be used for determining age. Ctenoid type: Rhinogobius scales Cycloid type: Anguillid eel scales Small and light scales like those of the eels offer less protection but it allows greater freedom of movement. Because all eels are adept at sudden reverse movements to withdraw from cover, protruding and overlapping scales would hinder such movements. Therefore, the reduction in scale size and its arrangement are considered as morphological specializations shown by all genera of eels which allowed them to inhabit holes and crevices and enabled them to move swiftly. Anguillid eel scales differ markedly from those of the other teleost fishes because it is microscopic, rudimentary, very thin, flat and well embedded in the skin in individual “sacs”, not arranged in overlapping rows and does not cover the whole body like in most teleost fishes. Important note: Unlike other teleost fishes, eels do not develop scales after larval stage but are formed first at a relatively large body size, usually three to four years after migrating into the freshwater environment (Tesch2003). Modified scales Scale diagram Description Spines Pufferfish Tetraodontidae Large scales Parrotfish Scariidae Adapted function Protection from predators Protection Modified scales Scale diagram Description Blades Surgeonfish Acanthuridae Adapted function Protection and defense Modified scales Scale diagram Tuna and jacks Scombridae and Carangidae Description Adapted function Scutes and keels Cuts through water, streamlines swimming Modified scales Scale diagram Description No scales Clingfish Gobiesocidae Adapted function Reduced drag Modified scales Scale diagram Description Adapted function Leathery scale Protection Bony armor Protection Leatherjacket Monacanthidae South American armored catfish Loricariidae Fish fins Terms and definitions of words used to describe fish Term Fins Definition If fish have appendages, they are thin, flat moveable fan-like parts. However, some fishes, like eels, do not have any appendages. https://twitter.com/Homeobox/status/1501303221666516999 Fish fins and locomotion Functions of fish fins • Dorsal fins: prevents rolling; used for stability • Pectoral fins: helps steer; sculls backwards •Pelvic fins: helps in stopping quickly; aids in stabilizing •Anal fins: protects the urogenital area; aids in stabilizing •Caudal fin: for propulsion Dorsal fin features Dorsal fin diagram Description Adapted function Spiny and softrayed dorsal fin Flared to make the fish look bigger Tucked dorsal fin Reduces drag in fast swimming fish Siamese fighting fish Betta splendens Yellowfin tuna Thunnus albacares Dorsal fin features Dorsal fin diagram Description Adapted function Locking spiny dorsal fin Locking fish into coral crevices Three dorsal fins Locomotion Leatherjacket Meuschenia scaber Atlantic cod Gadus morhua Dorsal fin features Dorsal fin diagram Centipede knifefish Steatogenys duidae Description Adapted function Very long dorsal fin Snake-like locomotion No dorsal fin Snake-like locomotion Caudal fin features Caudal fin diagram Description Rounded tail Ocean sunfish Mola mola Truncated Discus Symphysodon aequifasciatus Adapted function Large amount of surface area allows for effective accelaration and manuevering but creates drag causing fish to tire easily Effective acceleration and manuevering. Not much drag as a rounded shape Caudal fin features Caudal fin diagram Description Adapted function Lunate Rigid fin with less surface area means less drag and great acceleration but decreased manuevering. Ideal for continuous long distance swimming Blue marlin Makaira mazara Forked Milkfish Chanos chanos Good acceleration and manuevering. Less surface area means less drag Caudal fin features Caudal fin diagram Description Adapted function Pelagic thresher shark Alopias pelagicus Heteroceral (longer Slow or rapid upper lobe) tail swimming with bursts of speed Hypocercal (longer Generate upward lower lobe) tail force Flying fish Cheilopogon sp. Caudal fin features Caudal fin diagram Description Emarginate Blackbass Micropterus salmoides European eel Anguilla anguilla Pointed Adapted function Effective at acceleration and manuevering. Not as much drag as a rounded or truncate Swims at slow speed but highly manueverable; enable access to nooks and crevices Pectoral fin features Pectoral fin diagram Description Fringe-like pectoral fins Lionfish Scorpaenidae Adapted function Probing substrate Propping on Spiny pectoral fins substrate Pectoral fin features Pectoral fin diagram Description Adapted function Frogfish Anntenarrius sp. Hand-like pectoral Crawling on fins substrate Flyingfish Cheilopogon sp. Wing-like pectoral Soaring and fins swimming Pectoral fin features Pectoral fin diagram European eel Anguilla anguilla Nile tilapia Orechromis niloticus Description Adapted function No pectoral fins Snake-like swimming Normal size pectoral fins Maneuvering Pelvic fin features Pelvic fin diagram Description Adapted function Sucker-like pelvic Grabbing rocks by fins suction Yellowfin goby Acanthogobius flavimanus Thickened rays on Sitting on substrate pelvic fins Pelvic fin features Pelvic fin diagram Description Moderate sized pelvic fins Nile tilapia Orechromis niloticus Adapted function Locomotion Uniqued and specialized fins Fin diagram Description Adapted function Dorsal and anal fins Modified to increase propulsion Pectoral and tail fins Modified for soaring in air Longhorn cowfish Lactoria cornuta Flyingfish Cheilopogon sp. Body shape and fin types in relation to locomotion and habitat type Fish body shape Diagram of body Description Anguiliform (eel shape) Adapted function Maneuvering in crevasses Fusiform (bullet, or Lowering frictional torpedo shape) resistance in fast swimmers Fish body shape Diagram of body Description Depressiform (broad shape and flat top to bottom) Adapted function Lying on or below the surface of the sand Compressiform Entering vertical (tall, thin shape and crevices flat side to side) Fish body shape Diagram of body Description Vertically flattened shape that is somewhat depressiform (flat top to bottom) Fusiform (bullet, or torpedo shape), which is also sometimes called perch like Adapted function Bottom heavy for sitting on the bottom, not casting a shadow General all-purpose shape Fish body shape Diagram of body Description Elongated shape that is somewhat anguiliform (eel shape) Adapted function Ambush predators Mouth features Mouth diagram Description Adapted function Jawless Scavenging or parasitic behavior Tweezer-like snout Poking into crevices Butterflyfish Chaetodontidae Mouth features Mouth diagram Seahorse and pipefish Syngnathidae Pelican eel Eurypharyngidae Description Adapted function Suction tube Slurping in prey Large mouth Swallowing large prey Mouth features Mouth diagram Description Beak-like teeth Adapted function Biting hard objects Parrotfish Scaridae Tiny and turned up Capturing plankton Ponyfish Leiognathidae Teeth features Teeth diagram Description Adapted function Pointed Stabbing Comb-like Scraping material off rocks Viperfish and fangtooth Stomiidae Sicydiine goby Sicydiinae Teeth features Teeth diagram Description Adapted function Heavy and flat, molar like Grinding Fused like a beak Scraping hard materials off rocks Freshwater drum Sciaenidae Parrotfish Scaridae Teeth features Teeth diagram Description Incisor-like Sheephead Sparidae Adapted function Cutting Teeth features Teeth diagram Description Adapted function Broom-like Filtering Whale shark Rhincodon typus Steak knifelike Great white shark Carcharodon carcharias Serrated for sawing Eye features Eye diagram South American armored catfish Loricariidae Description Adapted function Tiny eyes, head length approximately six Receiving high times longer than eye intensity light width Large eyes, head length approximately three times longer Bigeye than eye width Pristigenys refulgens Receiving low intensity light or spotting predators Eye features Eye diagram Nile tilapia Orechromis niloticus Description Adapted function Average eyes head Receiving length three to five normal times longer than intensity light eye width Tubular eyes Barreleye Opisthoproctus soleatus Receiving low light from above often in deep water Fish Skeletal System • There are two different skeletal types: the exoskeleton, which is the stable outer shell of an organism, and the endoskeleton, which forms the support structure inside the body. • The skeleton of the fish is made of either cartilage (cartilaginous fishes) or bone (bony fishes). Fish skeletal system Osteichthyes Chondrichthyes Bony Fish versus Cartilaginous Fish • • • • • • • • • • Belongs to the class Osteichthyes Endoskeleton is made up of bones Found in both fresh and marine water More than 2700 species have been identified worldwide Has an airbladder for buoyancy Gills are covered with an operculum Has four pair of gills Excretes ammonia Exoskeleton is made up of thin bony plates known as cycloids Carnivores, omnivores, herbivores, filter feeders or detritivores • • • • • • • • • • Belongs to the class Chondrichthyes Endoskeleton is made up of cartilage Exclusively found in marine water More than 970 species have been identified worldwide Uses oil-filled liver for buoyancy Gills are not covered with an operculum Has five to seven pairs of gills Excretes urea Exoskeleton is made up of very small denticles coated with sharp enamel known as placoid Generally carnivores Fish Digestive System Digestive systems of fishes with different diets Rainbow trout (carnivore) Channel catfish (omnivore-animal source ) Common carp (omnivoreplant source ) Milkfish (microphagus planktivore) Gas/Swim Bladder • Gas-filled organ in the dorsal coelomic cavity (between the alimentary canal and the kidneys (Jones 1957; Marshall 1960) of fish. • Its primary function is buoyancy, but it is also respiration, sound production, perception of pressure (including sound). maintaining involved in and possibly fluctuations • It is filled with carbon dioxide, oxygen, and nitrogen in different proportions than occur in air, making the term “air bladder” inappropriate. Swim bladder and buoyancy • In the water, two forces act on a fish. The downward pull of gravity (due to weight) and the upward force of buoyancy (due to pressure of fluid). • A fish has a density of around 1.076 g/cm3 whereas the freshwater has a density of 1.0 g/cm3 and the saltwater as a density of 1.026 g/cm3. Thus, a fish is heavier than water and will sink if it stops swimming. • But the swim bladder decreases the average density of a fish and allows them to stay at a specific depth in water without swimming. Swim bladder is filled with oxygen; fish becomes lighter and floats up Swim bladder slightly deflated and smaller; fish remains at the same depth Swim bladder with less oxygen; fish sinks at the bottom Buoyancy in sharks All sharks are slightly negatively buoyant, which means they sink and they don't have gas-filled swim bladders to provide buoyancy. To avoid sinking, they rely on the following: 2. Very large liver that is full of low density oil. A shark’s liver can be up to 25% of its body weight. 1. A shark’s body is made primarily of cartilage and connective tissues, which are much lighter than bones. This helps keep them buoyant. 3. Some shark species swallow air at the water's surface and store it in their stomachs to adjust their buoyancy, an adaptation that allows them to move with minimal effort and hover in one position for lengthy periods. 4. Shark’s pectoral fins point downward, which helps lift the shark upwards . 5. Hydrodynamic lift from the shark’s heterocercal tail. Fish sensing Fish can detect vibrations, electric currents and smell/taste molecules Fish species detect lowfrequency underwater vibrations (from 1 to about 200 cycles per second) with their lateral line. This specialized sensory organ consists of a series of pores running in a line down each side of the fish's body. Each pore contains cells with hairlike processes, similar to those of the inner ear. These hair cells, called neuromasts, receive low-frequency sound waves and send a nerve impulse to the brain. Overlap occurs between frequencies catfish hear and those they feel with their lateral line. But hearing dominates when a sound originates far from the fish, while the lateral line becomes increasingly important when objects are closer. Some sensory cells in both the inner ear and lateral line are oriented in one direction, others in the opposite direction. This helps fish pinpoint the source of sound. Fish Lateral Line System • • Shark sensing Ampullae of Lorenzini: ampullae were initially described by Marcello Malpighi and later given an exact description by the Italian physician and ichthyologist Stefano Lorenzini in 1678, though their function was unknown. It can detect external vibration and lowfrequency electrical pulses for the detection of animate versus inanimate objects. Fish olfactory and optic systems Catfish have more than 175,000 taste buds on the surface of their bodies, making them virtual swimming tongues. The gills contain the highest concentration of taste buds, followed by the barbels and the mouth. How do fish “hear”? EAR-STONES OR OTOLITHS brain Fish hear with inner ears much like ours. The inner ear contains three semicircular canals for balance and three fluid-filled saclike structures for hearing. These sacs, lined with cells covered with fine hair-like projections, contain three calcium carbonate earbones called otoliths. circular canals Sound waves moving through water pass through a fish's body as if it weren't there because their body density nearly matches the density of water. When sound waves reach the otoliths, which are about three times denser than fish flesh, they vibrate at a rate different from the tissue surrounding them. Vibrations bend the hair-like projections on the cells, and nerves carry a sound message to the brain. Catfish can hear sounds of much higher frequency (up to 13,000 cycles per second) than other common gamefish. Catfish and minnows hear better than bass, trout, and other common gamefish because they have Weberian ossicles, bony structures that connect the swim bladder to the inner ear. The bladder acts as a resonating chamber to amplify vibrations, improving sensitivity and hearing range. Fish without Weberian ossicles hear sounds only from about 20 to 1,000 cycles per second. Fish sensing in areas where normal vision is Electric eel impaired (caves or muddy water) Gymnotiformes Electroreception is the ability to sense electrical signals. It is typically used for orientation or Elephant nose fishes object detection (electrolocation) or Mormyriformes communication (electrocommunication). Animals with active In electrocommunication, Animals with passive electrolocation usetheir specialized animals modulate electric electrolocation simply detect electric organs tosignal generate fields in order to to the fields produced by other electric fields and thenspecies detect members of the same animals irregularities within that field Knifefish Gymnotiformes Summary • A fish can be defined as an aquatic vertebrate with gills and with limbs in the shape of fins. Included in this definition is a tremendous diversity of sizes shapes, ecological functions, life history scenarios, anatomical specializations, and evolutionary histories. • The basic pattern of the cardiovascular system is a single-pump, single-circuit system that goes from the heart to gills to body and back to the heart. • Fish gills provide a large surface area for gas exchange, and the countercurrent flow of blood and water across the lamellae maximizes the efficiency of gas exchange by diffusion. Some fishes have special adaptations to allow them to breathe air. • The skin and its derivatives, such as scales in fishes, provide external protection. The five basic types of scales are placoid, cosmoid, ganoid, cycloid, and ctenoid. • The anterior region of the alimentary tract consists of the buccal cavity (mouth) and the pharynx. The posterior region consists of the foregut (esophagus and stomach), midgut or intestine, and hindgut (rectum). Alimentary tract length and structure differ as a function of feeding habits. • Many fishes that live in the water column use buoyancy control mechanisms, such as the addition or release of gases from the gas bladder, to save energy. • Sensory systems convert stimuli from a fish’s environment into biological signals (nerve impulses) that can be integrated, interpreted, and acted upon. • Disturbances in the water are sensed by neuromasts, clusters of sensory hair cells and supporting cells covered by a gelatinous cupula. Neuromasts may be free-standing in a fish’s skin or located in canals beneath the scales along the trunk (the lateral line) or in the dermal bones of the head. Small pores allow vibrations from the surrounding water to enter these canals. • Equilibrium, balance, and hearing are mechanoreceptive senses primarily located in various chambers of a fish’s inner ear. The relative movement of fluid (endolymph) or solid deposits (otoliths) stimulates sensory hair cells, which generate signals that are subsequently carried to the brain by sensory nerves. • Some teleosts possess specialized organs capable of generating an electric field which is subsequently received by tuberous receptors. These fishes utilize this sensory system to gather information about their environment and to communicate with conspecifics. Thank you… Nico Jose S. Leander, Ph.D. Regional Fisheries Research and Development Center Bureau of Fisheries and Aquatic Resources Region 3 Diosdado Macapagal Government Center, Maimpis, City of San Fernando, Pampanga Email: [email protected] [email protected]