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Colouration & Importance of colour
VISHNU G.
Colourational Defense
• I am some one else
• I am not tasty
• I am dangerous
• I am not here
Cryptic colourat
ion
Revealing
colouration
MimicryWarning colourat
ion
1. Crypsis
Colouration that makes animals difficult to distinguish against their background
Crypsis works only if the animal is resting on the appropriate background and usually only when the animal is not moving
HomotypismHomomorphismHomochromism
Homochromism
• Similarity of animals to the colour of inanimate objects
• These insects are often the same colour as the leaves or twigs on which they rest
Homomorphism
Similarity of animals to the form of inanimate objects
These insects are often the same form as the leaves or twigs on which they rest
Homotypism
• Similarity of animals to the colour & form of inanimate objects
• Same colour & form as the leaves or twigs on which they rest
The South Indian Blue OakleafKallima horsfieldii, Nymphalidae
2. Revealing colouration
Deimatic behavior
Any pattern of threatening or startling behavior
such as,
suddenly displaying conspicuous eye spots - to scare
off or momentarily distract a predator thus giving the prey
animal an opportunity to escape
Deimatic behavior
• Dynamic, frightening or startle behavior
• Display of some conspicuous colour or structure
• Static display
• Deep red or black hind wing
• Praying mantids & Phasmids
• Phymateus sp, Smerinthus ocellatus, Aglais io
Shock
Smerinthus ocellatus
Aglais ioPhtmateus spPyrgomorphidae
Surprise !!!
Surpris
e !!!
3. Warning colouration
Aposematism
The correlation between conspicuous signals, such as
bright colouration & prey unprofitability
Candy Rowe, 2001
Brightly Coloured Species – Puzzle for Biologist
Henry Walter
Sexual selection 1866
Historic approach
1862
Pseudosphinx hawk moth caterpillar
Experimental proof
1867
Unpalatable species
1866
Aposematism
1890
Apos
emat
ic co
lour
atio
n
Brightly Coloured Species – Puzzle
for Biologist
Antipredator adaptation
Advertising signal
Exploited in Mullerian mimicry
Greek word – Apo = Away & Sema =
Sign Signs that warn other animals
away
Aposematic insectsSpecies Stage Colour Basis of unpalatability
Zonocerus variegatus Adult B/Y & R markings Various chemicals
Romalea guttata Adult B/R hind wings Various chemicals
Aphis nerii All Bright yellow Cardiac glycosides
Oncopeltus fasciatus Adult Y/B spots Cardiac glycosides
Coccinella septemfasciata Adult R/B spots Alkaloids
Hycleus lugens Adult Yellow spots Alkaloids
Vespula vulgaris Adult Y/B stripes Sting
Tyria jacobaeae Larva B/Y stripes Pyrrolizidine alkaloids
Tyria jacobaeae Adult B/R marks Pyrrolizidine alkaloids
Danaus plexippus Larva W/B & Y stripes Cardiac glycosides
Zygaena filipendula Adult B/R spots Cyanogenic glycosides
Reference - The insects structure & function (2011): R. F. Chapman
Orthoptera
Zonocerus variegatus
Romalea guttata
Reference - The insects structure & function (2011): R. F. Chapman
Hemiptera
Aphis nerii
Oncopeltus fasciatus
Reference - The insects structure & function (2011): R. F. Chapman
Coleoptera
Hycleus lugens
Coccinella septemfasciata
Reference - The insects structure & function (2011): R. F. Chapman
Hymenoptera
Vespula vulgaris
Reference - The insects structure & function (2011): R. F. Chapman
Larval Lepidoptera
Tyria jacobaeae
Danaus plexippus
Reference - The insects structure & function (2011): R. F. Chapman
Lepidopteran adult
Tyria jacobaeae
Zygaena filipendula
Reference - The insects structure & function (2011): R. F. Chapman
4. Mimicry
• Resemblance of one
species to another
• I am someone else
• Related to Camouflage
Defensive
Aggressive
Auto/Self
Defensive/ Protective mimicry
• It takes place when organisms are able to avoid an
encounter that would be harmful to them by deceiving an
enemy into treating them as something else
Batesian mimicry
Mullerian mimicry
Martensian/ Emsleyan mimcry
Wasmannian mimicry
Batesian mimicry
• A harmless mimic poses as harmful
A sheep in wolf’s clothing
• Also known as Parasitic mimicry
• Mimic - emits signals similar to model but does not possess
the attributes that makes it unprofitable to predators
Henry Walter Bates
Mimic ModelNormal
Mimic ModelNormal
Mullerian mimicry
• Two harmful species share similar perceived
characteristics
• Mutualistic mimicry or Convergence
• Predation on any one species is reduced
• When two poisonous species have similar markings; fewer
insects need to be sacrificed in order to teach the predators
not to eat these unpalatable animals
Fritz Muller
Heliconius sp.
Phonoctonus sp.
Dysdercus sp.
Wasmannian mimicry
• The mimic resembles a model along with which it lives as an inquiline in a nest or colony
• Most of the models here are social insects such as ants, termites, bees & wasps
Erich WasmannAraeoschizus sp Reichenbachia spatulifer
Mertensian/ Emsleyan mimicry
• Named after M. G. Emsley & German herpetologist Robert
Mertens
• A deadly mimic resembles a less harmful but lesson-
teaching model
Robert Mertens
Aggressive mimicry
• Also known as Peckhamian mimicry after George &
Elizabeth Peckham
• Predators or parasites which share characteristics with a
species harmless to their prey, allowing them to avoid
detection by the latter
• Mimic may resemble the prey or host itself
• The model may be affected –vely, +vely or neutral
Automimicry/ Interspecific mimicry
• The species relationship between model & mimic
• Occurs within a single species one case being where one
part of an organism’s body resembles another part
• Mimic imitates other morphs within the same species
• Deflection marks in Lycaneid butterfly
Deflection marks
Deflection marks are those which divert the attack of a
predator away from the most vulnerable part of an animal
to where it will do minimal damage
Polycephalic Butterflies
Arawacus aetolus
Cycnus phaleros
Rekoa palegon
Atlides atys Calycopis isobeon
References
Chapman, R. F. (2011). Visual signals: Colour and light production. The insects structure & function (4th edition), pp. 657-679.
Robert K. Robbins, The American Naturalist. The “False Head” Hypothesis: Predation and Wing Pattern Variation of Lycaenid Butterflies. Vol. 118, No. 5 (Nov., 1981), pp. 770-775