Lecture 12 - Antipredator behaviors

A set of methods of concealment that allows otherwise visible animals to remain unnoticed by blending with their environment or by resembling something else

Camouflage

2 types of camouflage

crypsis and masquerade

Blending with background, making animal hard to see or detect in other ways (like sound or scent)

Crypsis

Disruptive coloration, countershading, transparency, or color matching are examples of what kind of camouflage?

Crypsis

The whole animal looks like some other object, which is of no special interest to observing animal.

Masquerade (mimesis)

Type of camouflage where coloration that blends into visual background

form of crypsis

Polymorphism

2 or more clearly different phonotypes exist in the same population of a species

Advantage of polymorphism in camouflage

gives the species color variation to exist in a wider range of habitats and still be able to use camouflage

Decoration behavior

animals actively make themselves cryptic by using materials from environment to conceal their outlines

Countershading

use of graded color to give illusion of flatness

Counter illumination

producing light to match a background that is brighter than animal’s body

• form of active camouflage

Motion camouflage

dynamic type of camouflage by which an object can approach a target while appearing to remain stationary from perspective of target

Is motion camouflage a form a camouflage used for predator avoidance?

NOOO

Coloration using strongly contrasting marks like spots or stripes designed to prevent the perception of an animal’s form

Disruptive coloration

Difference between disruptive coloration and cryptic coloration:

• disruptive = breaks up animal’s outline making it harder to recognize/see

• cryptic = allows animal to blend in

Type of disruptive coloration that works better when animal is in motion

Dazzle pattern (zebras)

Specialized type of camouflage where animal is not hidden from view but instead looks like something else

Masquerade

Warning coloration, a family of antipredator adaptations where a warning signal is associated with the unprofitability of a prey item to potential predators

Aposematism

Who are aposematic signals beneficial to?

both predator and prey, both avoid potential harm

How do predators avoid aposematic prey?

either through innate knowledge of aposematic animals or through learning

Ability of one animal to look like another animal

Mimicry

Form of mimicry when two or more poisonous species which share one or more common predators, have come to mimic each other’s warning signals

Mullerian mimicry

Benefit of mullerian mimicry

the predator’s experience with one species will teach it to avoid the other species also

Rattlesnakes perform which kind of mimcry?

mullerian mimicry

Form of mimicry where a harmless species has evolved to imitate the warning signals of a harmful species directed at a common predator

Batesian mimicry

In batesian mimicry which animal is the mimic and which is the model?

• mimic = organism imitating the protected species

• model = imitated organism

Who benefits and who’s harmed in batesian mimicry?

• mimic benefits because gains same advantage as model without the expense of arming itself

• model harmed because positive experiences with mimic may result in model being treated as harmless

The act where an animal loses one or more of its own body parts, usually as self defense designed to elude predator’s grasp.

Autotomy

Strategy of making a less vulnerable portion of the body look like its head

False heads

Immobility elicited by presence of or contact with predator

Death feigning

Threat displays

form of aggression as antipredator defense, including an apparent increase in size, exposure of weapons, and threatening sounds and postures

Ocellus/Ocelli

eyespots

Ocelli as antipredator defense

aggressive display used to scare of predators

• can also give false head illusion

Jumping into air with legs straight and stiff, with white rear fully visible, signals unprofitable chase

Stotting

Members of a species drive away their predator by cooperatively attacking or harassing it

Mobbing behavior

Antipredator adaptation referring to various signals omitted by social animals in response to danger

Alarm signals

Group defense allows for decreased chance of becoming a vistim of predation through _______-.

Dilution effect

Phenomenon where individuals living in groups are safer from predators because predator has more targets to choose from

Dilution effect

Effects of dilution effect

• any one herd member unlikely to be preyed upon

• predator satiation likely to occur in high populations

Antipredator adaptation in which prey occur at high population densities, reducing probability of an individual organism being eaten

Predator satiation

Dilution effect vs predator aggregation

• dilution effect relatively permanent

• predator aggregation limited to special events (ex. migration)

Antipredator mechanism that considers the spatial arrangement of individuals within the group

Selfish herd

Group mediated antipredator technique in which a predator would be less successful targeting and capturing one prey item in a group

Confusion effect

• unable to single out and attack an individual