Signalling Animal coloration

1 signalling

1.1 advertising services
1.2 sexual selection
1.3 warning

signalling

colour used signalling in animals diverse birds , shrimps. signalling encompasses @ least 3 purposes:

advertising, signal capability or service other animals, whether within species or not
sexual selection, members of 1 sex choose mate suitably coloured members of other sex, driving development of such colours
warning, signal animal harmful, example can sting, poisonous or bitter-tasting. warning signals may mimicked truthfully or untruthfully.

advertising services

cleaner wrasse signals cleaning services big eye squirrelfish

advertising coloration can signal services animal offers other animals. these may of same species, in sexual selection, or of different species, in cleaning symbiosis. signals, combine colour , movement, may understood many different species; example, cleaning stations of banded coral shrimp stenopus hispidus visited different species of fish, , reptiles such hawksbill sea turtles.

sexual selection

male goldie s bird of paradise displays female

darwin observed males of species, such birds of paradise, different females.

darwin explained such male-female differences in theory of sexual selection in book descent of man. once females begin select males according particular characteristic, such long tail or coloured crest, characteristic emphasized more , more in males. males have characteristics females sexually selecting for, males can reproduce. mechanism powerful enough create features disadvantageous males in other ways. example, male birds of paradise have wing or tail streamers long impede flight, while brilliant colours may make males more vulnerable predators. in extreme, sexual selection may drive species extinction, has been argued enormous horns of male irish elk, may have made difficult mature males move , feed.

different forms of sexual selection possible, including rivalry among males, , selection of females males.

warning

a venomous coral snake uses bright colours warn off potential predators.

warning coloration (aposematism) opposite of camouflage, , special case of advertising. function make animal, example wasp or coral snake, highly conspicuous potential predators, noticed, remembered, , avoided. peter forbes observes, human warning signs employ same colours – red, yellow, black, , white – nature uses advertise dangerous creatures. warning colours work being associated potential predators makes warning coloured animal unpleasant or dangerous. can achieved in several ways, being combination of:

the black , yellow warning colours of cinnabar moth caterpillar, tyria jacobaeae, instinctively avoided birds.



distasteful, example caterpillars, pupae , adults of cinnabar moth, monarch , variable checkerspot butterfly have bitter-tasting chemicals in blood. 1 monarch contains more enough digitalis-like toxin kill cat, while monarch extract makes starlings vomit.
foul-smelling, example skunk can eject liquid long-lasting , powerful odour
aggressive , able defend itself, example honey badgers.
venomous, example wasp can deliver painful sting, while snakes viper or coral snake can deliver fatal bite.

warning coloration can succeed either through inborn behaviour (instinct) on part of potential predators, or through learned avoidance. either can lead various forms of mimicry. experiments show avoidance learned in birds, mammals, lizards, , amphibians, birds such great tits have inborn avoidance of colours , patterns such black , yellow stripes.