Forms of Communication Lecture PDF

Lecture 3 Forms of communication Visual communication Odor or chemical communication Auditory communication Tactile communication Electrocommunication 1 1. Visual communication Information transmitted by visual means...

Lecture 3 Forms of communication Visual communication Odor or chemical communication Auditory communication Tactile communication Electrocommunication 1 1. Visual communication Information transmitted by visual means is called visual communication. The visual signals may be given by various means like: 1. Movement 2. Posture or shape of the body 3. Facial expressions. 4. Color and displays 5. Light. Visual signals are used most often by species that are active during day. 2 1. Movement The worker bees communicate about food mainly by a dance language. Bees mainly perform 2 types of dances A. Round dance B. Waggle dance 3 Round dance If source of nectar is less than about 100m away. Does not communicate the direction. Runs around in narrow circles, suddenly reversing direction to her original course. After the round dance has ended, she often distributes food to the bees following her. Essentially says "There is food close by, get out and find the food.” 4 B. Waggle dance: If source of nectar more than 100m away from hive. Communicates both distance and direction. Runs straight ahead for a short distance, returns in a semicircle to the starting point, runs again through the straight course, then makes a semicircle in the opposite direction to complete a full, figure-eight circuit. While running the straight-line course of the dance, the bee wags abdomen, vigorously sideways. The angle that the bee adopts, relative to vertical represents the angle in which food is found. 5 2. Postures Some mammal species give specific signals by the position adopted by head, ears & tail. 3. Facial expressions 6 4. Colors and Displays I. Colors During mating season, the male goldfinch has a bright yellow body. II. Display When an animal exhibits a behavior that can be seen by other animals, it is called a display. Male fiddler crabs wave their giant claw to attract female fiddler crabs. Male bird of paradise exhibits a visual display as part of its courtship behavior. 7 5. Light (Bioluminescence) Certain animals communicate via their light signals during night. Bioluminescence is light produced by a chemical reaction within a living organism. Bioluminescence is a type of chemiluminescence, which is simply the term for a chemical reaction where light is produced (Bioluminescence is chemiluminescence that takes place inside a living organism.) Bioluminescence is a "cold light". 8 Bioluminescence Most bioluminescent organisms are found in the ocean. These bioluminescent marine species include fish, bacteria, and Comb jellyfish. Some bioluminescent organisms, including fireflies and fungi, are found on land. There are almost no bioluminescent organisms native to freshwater habitats. 9 Bioluminescent Light The appearance of bioluminescent light varies greatly, depending on the habitat and organism in which it is found. Most marine bioluminescence, for instance, is expressed in the blue- green part of the visible light spectrum. These colors are more easily visible in the deep ocean. Also, most marine organisms are sensitive only to blue-green colors. They are physically unable to process yellow, red, or violet colors. Most land organisms also exhibit blue-green bioluminescence. However, many glow in the yellow spectrum, including fireflies. 10 Bioluminescent Light Some species of comb jellyfish, or Ctenophora, are examples of this. The comb jelly produces blue or green light, but the movement of its combs can scatter the light, producing a rainbow effect. The light produced by comb jellies can be used to both confuse and attract predators. 11 Bioluminescent Light Few organisms can glow in more than one color. The so-called railroad worm (actually the larva of a beetle) may be the most familiar. The head of the railroad worm glows red, while its body glows green. Different luciferases cause the bioluminescence to be expressed differently. 12 Bioluminescent Light Some organisms emit light continuously. Most organisms, however, use their light organs to flash for periods of less than a second to about 10 seconds. 13 1. In order for this reaction to occur, a chemical named “Luciferin”, which emits light, is required. 2. First, luciferin bind with an enzyme “luciferase”. This enzyme acts as a catalyst to speed up the reaction. 3. Then, oxygen is needed to oxidize the reaction. 4. As a result of this chemical reaction, energy is released in a form of light. 14 Luciferin Some bioluminescent organisms produce (synthesize) luciferin on their own. Dinoflagellates, for instance, bioluminesce in a bluish-green color. Bioluminescent dinoflagellates are a type of tiny marine organisms that can sometimes cause the surface of the ocean to sparkle at night. 15 Luciferin Some bioluminescent organisms do not synthesize luciferin. Instead, they absorb it through other organisms, either: as food or in a symbiotic relationship. A.As food Some species of midshipman fish, for instance, obtain luciferin through the "seed shrimp" they consume. 16 Luciferin A midshipman fish is bioluminescent. It has photophores in the skin of its head and much of its body. One fish has over 700 photophores, each about a millimeter wide. They contain luciferin and produce a distinct fluorescent green glow. The fish is only luminescent during courtship. 17 Not all individuals express this trait There are two main populations of the species, a southern population in San Francisco, and a northern population in Oregon. Fish of the southern population are bioluminescent, but most northern fish are not. The nonluminescent fish lack luciferin in their photophores. 18 The ostracod crustacean In experiments, nonluminescent fish can be made luminescent by dosing them orally or by injection with luciferin obtained from the luminescent ostracod crustacean. This crustacean has a similar, but not identical, luciferin compound which can apparently function in the photophores of the fish, as well. 19 B. A symbiotic relationship Many marine animals, such as squid, house bioluminescent bacteria in their light organs. The bacteria and squid have a symbiotic relationship. Bioluminescent bacteria, Photobacterium, are light-producing bacteria. These bacteria are in symbiosis with animals such as the Hawaiian Bobtail squid. The host organisms provide these bacteria a safe home and sufficient nutrition. In exchange, the hosts use the light produced by the bacteria for camouflage, prey and/or mate attraction. 20 Uses of Bioluminescence Bioluminescence is used by living things to hunt prey, defend against predators and find mates. 1. Defensive Adaptations a) The vampire squid exhibits a defensive behavior. Like many deep- sea squid, the vampire squid lacks ink sacs. The tips of its tentacles emit a cloud of bioluminescent sticky mucus that glows for up to 10 minutes, plenty of time for the squid to escape a predator. 21 Defensive Adaptations b) Many marine species use a technique called counterillumination to protect themselves. Many predators, such as sharks, hunt from below. They look above, where sunlight creates shadows beneath prey. Counterillumination is a type of camouflage against this predatory behavior. 22 Defensive Adaptations Hatchetfish use counterillumination. Hatchetfish have light-producing organs that point downward. They adjust the amount of light coming from their undersides to match the light coming from above. By adjusting their bioluminescence, they disguise their shadows and become virtually invisible to predators looking up. 23 Defensive Adaptations c) Some bioluminescent animals, such as brittle stars, can detach body parts to distract predators. The predator follows the glowing arm of the brittle star, while the rest of the animal crawls away in the dark. (Brittle stars, like all sea stars, can re-grow their arms.) The Brittle Star uses light to warn predators of its unpleasant taste. 24 Defensive Adaptations d. When some animals detach body parts, they detach them on other animals. When threatened, some species of sea cucumber can break off the luminescent parts of their bodies onto nearby fish. The predator will follow the glow on the fish, while the sea cucumber crawls away. 25 Defensive Adaptations e. Firefly larvae do not use luminous signals for sexual purposes because they cannot reproduce during this life stage, so there has been much speculation as to the function of luminescence in larvae. Firefly larvae use their photic emissions as aposematic displays and it has been shown that fireflies possess distasteful steroids, termed lucibufagins, in their hemolymph. A mouse as a predator, could associate a bioluminescent glow with a distasteful substance. 26 2. Offensive Adaptations Bioluminescence may be used to lure prey or search for prey. a) The most famous predator to use bioluminescence may be the anglerfish, which uses bioluminescence to lure prey. b) Other fish, such as a type of dragonfish called loosejaws, use bioluminescence to search for prey. Loosejaws has 2 different bioluminescent lights: one produces blue-green light the other (under the eye) produces long IR (red) light. 27 Offensive Adaptations They produce their own light to help them find prey, avoid predators, and attract mates. Their bodies are lined with small glowing patches called photophores. These organs produce blue-green light -- the wavelengths that travel farthest in the ocean. The dragonfish produces a red light beam using a unique organ located near its eye. It is one of the few deep sea creatures that can perceive red light to sneak up on their prey, especially shrimp. 28  IR light or red light are invisible to most deep sea animals so they can see their prey, but their prey can't see them. It can also communicate with other members of its species -- using a flashlight that only another dragonfish can see. 29 3. Attraction a) Adult fireflies are bioluminescent. They are soft-bodied beetles that are commonly called fireflies, glowworms, or lightning bugs for their conspicuous use of bioluminescence during twilight to attract mates. 30 Lantern A firefly controls the beginning and end of the chemical reaction, and thus the start and stop of its light emission, by adding oxygen to the other chemicals needed to produce light. This happens in the insect's light organ (luminescent organ), Lantern. When oxygen is available, the light organ lights up, and when it is not available, the light goes out. Insects do not have lungs, but instead transport oxygen from outside the body to the interior cells within through a complex series of successively smaller tubes known as tracheoles. 31  The luminescent cells of lantern are close to the cells at the end of tracheoles (that bring O2 and take away CO2 from tissues). The lantern is regulated by flow of oxygen & nitric oxide (NO). Researchers fairly recently learned that nitric oxide gas plays a critical role in firefly flash control. Nitric oxide (NO) is a soluble, highly reactive gas produced by certain animal cells from the amino acid, L-arginine. Because it is so small and diffusible NO passes through cell membranes and is often used as a biological signal. 32  NO can inhibit oxygen consumption by mitochondria and it is this action that is exploited in producing firefly light flashes. The presence of nitric oxide, which binds to the mitochondria, allows oxygen to flow into the light organ where it combines with luciferase and luciferin (contents of peroxisome). As such, the O2 content in the cells increase and this turns on light production in peroxisomes. 33  In short, when the firefly light is “off”, no nitric oxide is being produced. In this situation, oxygen that enters the light organ is bound to the surface of the cell's energy-producing organelles, called the mitrochondria. 34 Flash termination In the firefly lantern, flash termination could occur as NO is rapidly degraded by the CNS signal that stimulates NO production. Because nitric oxide breaks down very quickly, as soon as the chemical is no longer being produced, the oxygen molecules are again trapped by the mitochondria and are not available for the production of light. 35 Fireflies signaling 1) Both males and females use bioluminescence (ex: Hotaria parvula). 2) female produces light to attract male (ex: Microphitus sp.). 3)females use pheromones to attract males and when in close proximity, glow (ex: Pleotomus pallens). 36