Antipredator Behavior

“How to avoid being eaten”

avoid being seen

advertise unprofitability

be vigilant

if caught, go for broke

How not to be seen Method 1a:Pick a background with similar color or pattern (minimize contrast )

Camouflage in moths

How can we experimentally determine that it works?

Pin moths to tree and see which get eaten…

Crab spiders mimic flowers to both escape detection by predators and to attract prey

Crab Spiders

How not to be seen Method 1b:Mimic some aspect of the environment (be cryptic)

How not to be seen Method 2:Use the environment to manipulate your pattern/color to match environment

Caddisfly

Artificial camouflage

Decorator crabs

Crabs put algae on their backs, which increases their survival

In areas with Dictyota algae, use this species for decoration, but rarely food

Artificial camouflage

Decorator crabs

Crabs put algae on their backs, which increases their survival

In areas with Dictyota algae, use this species for decoration, but rarely food

Decorator crabs, cont.

Did this preference arise by natural selection?

All crabs in areas with Dictyota show preference.

Crabs with Dictyota have survival advantage.

Algae produces chemicals that are distasteful to fish!

How not to be seen Method 3:Manipulate your pattern/color directly to match environment.

Rapid adaptive camouflage in tropical flounders V. S. Ramachandran and colleaguesNature. 1996

Flounders (flat fish) can mimic backgrounds within 2-8 seconds!

Advertise unprofitability

An alternative to hiding is to be dangerous and let predators know.

aposematic (warning) coloration

Produce toxins – Monarch butterfly

Actually subverts plant’s anti-herbivore chemical defenses to it’s own anti-predator defenses!

Why be toxic and advertise if predators have to eat you to learn to avoid you?

No group selection needed:

Not always killed by attack

Predators learn very quickly

Other producers of nasty chemicals:

Skunk Bombardier beetle

Eyelash viper

Eisner and Aneshansley, 1999, PNAS

Mullerian Mimicry: 2 or more distasteful or harmful organisms resemble each other

Monarch butterfly Viceroy butterfly

High toxicity correlated with diet specialization (ants).

Santos et al. 2003 PNAS

Ants appear to be the source of pumiliotoxin alkaloids.Saporito et al. 2004. PNAS

Batesian Mimicry: defenseless species (mimic) is protected from predation by its resemblance to a species that is dangerous (toxic).

fly (bee mimic) bumble bee

Need to mimic behavior too!

Texas coral snake Kingsnake

Eastern Hognose snake Western Hognose snake

Edible prey warning behavior:

I see you, and I can run faster than you, so do both of us a favor and don’t even bother trying!

Stotting behavior in ungulates

Why do ungulates stot?

H1: Advertise unprofitability

H2: Alarm signal to offspring/others

H3: Social cohesion

H4: Confusion effect

Be vigilant – don’t get eaten

Many prey constantly watching for predators, even while sleeping

Vigilance behavior shapes morphology – eyes on side of head, antlers…

Effective level of vigilance increases in groups (another lecture)

“flatfish”

American Woodcock

Antlers: grow from pedicels (bony supporting structures), males only, shed annually (family Cervidae)

Horns: composed of a bony core covered with a sheath of keratin, never branched (unlike antlers), occur in males and often females (family Bovidae)

Horned lizards (genus Phrynosoma)

What to do if you’re caught?

Anything possible!

Geckos can drop their tails when threatened by a predator, which is not as bad as death!

Death (?) screams

Why do some prey scream loudly after being caught?

H1: It’s a response to pain receptors being activated (proximate!)

H2: It warns conspecifics (but it says the predator is currently busy!)

H3: It elicits parental help

H4: Screaming attracts other predators

Pike & fathead minnows-

When captured, minnows release chemical that attracts other predators

Presence of two pike and one minnow increased the time to swallow the minnow, and a few times the minnow escaped!

Cephalotes atratus

Cephalotes clypeatus

Stephen Yanoviak, Robert Dudley, and Michael KaspariDirect aerial descent in canopy ants. Nature. 2005