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Canada (162,047)
Biology (111)
BIOL 1902 (6)
Chapter 1

Chapter 1 - Staying Alive.pdf

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BIOL 1902
Michael Runtz

Background matching: when an animal’s appearance closely resembles its immediate surrounding • Cattail marshes are an expanse of vertical lines due to the stems of the dominant plants • Female Red-winged Blackbirds andAmerican Bitterns have striped feathers • When alarmed they point their bills upwards, making their entire body mirror their surroundings • Similar to Savannah Sparrows in grasslands • Light reaches forest floors in dappled fragments • To camouflage, animals must have high contrast patches or flecks • Wood Thrushes and Fawns are examples • Brown, grey and black are more effective due to the presence of dead leaves and organic debris • Exemplified by Ruffed Grouse • Only effective when the animal is motionless • Beneficial for an animal to resemble bark or lichens in arboreal settings • Eastern Screech Owls often occupy vacant cavities in trees, which due to their pattern, makes the bark look continuous • The spots on the Leopard Frog allow it to blend in with floating vegetation • Gray Tree Frogs bend their front legs under their chest, making them become one with the tree • GTFs can also change their color from gray to green if lichens are present on the tree Disruptive Coloration Amphibians and reptiles: • The lines of LF and GTFs disrupt the animal’s edges, thereby delineating the animal’s outline, dissecting it into sections of light and dark This makes it difficult to match the animal’s form to a search image • Birds: • Disruptive coloration can take the form of markings or patterns that are exposed only in certain situations • Horned Larks and Killdeer have disruptive patterns in the form of dark bands across their breast and face • Songbirds usually have a dark line through their eye, with a wide pale band above it, and a pale central stripe on the top, which acts as a disruptive pattern when the bird sits in its nest with only its head exposed above the rim Mammals: • Chipmunks have facial marking and stripes running across their back • Raccoons sport wide dark bands across their face which helps conceal their eyes, one of the most conspicuous parts of the animal • Coincident disruptive patterns: disruptive markings which come into play when an animal assumes a certain posture (ex. grasshoppers) • When the Leopard Frog is at rest, its hind legs are bent, making patterns from the upper and lower body align, creating a larger, continuous disruptive pattern Bicolouration: • Aquatic insects, such as Whirligigs, which spend time on the surface must avoid detection from above and below • Dark upper body to match dark pond floor, from an ariel view • Pale bottom to blend with sky from an aquatic view • Notonectids have the inverse of the above and swim on their backs Countershading/Self-shadow: • Usually in areas with sunlight, so top part of body shades lower part • Having a lighter underside would mean that this shade evens out the animal’s color • This renders it one-dimensional and therefore less obvious • Only works when an animal doesn’t move • This is why many birds freeze when in danger (if they can’t flee), to exploit this feature Masquerade: matching the background in form • Walking Sticks and many Inchworm caterpillars bear resemblance to twigs • Anglewing butterflies (Commas and their kin) appear as dead leaves • Luna Moths appear as green foliage May involve changing posture: • Some moths fold their wings, making them appear as curled-up leaves • They may also tuck their heads in to eliminate protrusions Appear as inedible objects: • Giant Swallowtails and Viceroys resemble bird droppings, which predators would not consume • Larvae of Scarlet Lily Beetles cover their bodies in excrement Adding material to the body: • Caddisfly larvae bind together bits of debris with silk to create little houses that resemble debris lying on the bottom of aquatic habitats • Caterpillars, such as Casebearers, add plant fragments to their bodies Startle Patterns: shocking marking which appear unexpectedly • Sphinx and Underwing moths are usually camouflaged into tree bark, but have very bright pattern when their wings are opened • The sudden appearance of bright colors would startle predators, giving it time to fly away • Red-bellied snakes have red bellies *facepalm* • Grey Tree Frogs have bright yellow on the inner part of their hind thighs, which show only when they leap • Effective because they are hidden most of the time • The colors of Sphinx moths often look like eyes • There are usually several species of Sphinx or Underwing moths in any given area, each with unique startle patterns, as predators may become habituated to any single pattern • If a predator recovers from the initial startle, it will usually attack the brightly colored portion, which in most cases, is non-vital, and the animal can continue living without it Deflection Structures: • Five lined skinks hide beneath rocks and scurry away when uncovered • If the predator is fast enough to catch the tail, it immediately disconnects due to a layer of cells that weaken its connection • The tail thrashes through muscle spasms, focusing attention • Crane flies can detach their legs (do not grow back) • Swallowtails, Hairstreaks and Tailed Blues have “tails” that project from the base of the hind wing, with a bright marking adjacent. When viewed from the side, this looks like a head with an antennae, deflecting the attack to the wing rather than the head • Eyed elaters and caterpillars of Tiger Swallowtail butterflies and Pandora Sphinx moths, have eyespots permanently on display • This makes them look larger than they actually are Sphinx moth caterpillars further the illusion by “hissing” • • Swallowtail caterpillars emi
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