FEEDING ECOLOGY OF AMPHIBIANS AND REPTILES

When you are hungry what do you do?

1. Dig out wallet/open fridge2. Decide what you want/can eat3. Capture Food Item4. Cook Food Item5. Consume Food Item6. Digest7. Repeat

FEEDING ECOLOGY OF AMPHIBIANS AND REPTILES

When a herp is hungry what does it do?

1. Dig out wallet/open fridge—Wild Food Has Cost2. Decide what you want/can eat—Limitations of Cost3. Capture Food Item—Often the major cost4. Cook Food Item5. Consume Food Item—Not as easy as it sounds6. Digest—another big cost7. Repeat—When and how much8. Hope Nobody Eats You—A REALLY BIG COST9. Hope Dinner Doesn’t Bite You Back—PARASITES

FEEDING ECOLOGY OF AMPHIBIANS AND REPTILES

What do amphibians and reptiles eat?

FEEDING ECOLOGY OF AMPHIBIANS AND REPTILES

What do amphibians and reptiles eat?

Salamanders: Mostly Inverts

Frogs: Animals

Tadpoles: Filter feed, algae, larger foods

Caecilians: Animals

Snakes: Mostly vertebrates, some Inverts

Lizards: Mostly insects, Some vertebrates

Tuatara: Inverts

Iguaninae: Herbivores

WHY ARE THERE SO FEW HERBIVOROUS HERPS

Challenges of Herbivory: Very low energetic value May not be an option for small animals

Gut FloraRotting in the Gut—Cold Temperatures

Successful Herbivores: Iguanas, 2 Other LizardsTadpoles (Are Algae Plants?)

FINDING SOMETHING TO EAT

•Active Predators vs Sit and Wait

•Risks of Both•Predation•Energy Gained/Lost•Your Defense

•Chemical Responses

•Coevolved Prey

•Phylogenetic Effects

Specializations for Feeding

Suction Feeding

1. Only Works in Water2. Primitive: How Most Bony Fish Eat3. Difficult to Do Without Gill Slits

Specializations for FeedingSuction Feeding:

Primitive Form of Larval and Paedomorphic Salamanders

Figs 11-1a, 11-2

Specializations for Feeding

Suction Feeding:Modification in Tadpoles

Fig11-10, 11-6, 11-7. 11-8

Specializations for Feeding

Suction Feeding:Challenge of Life Without Gills

Water flow is now 2 directional.How is this a problem?

Figs 11-1b

Now suction gives the predator a brief advantage, or at least reduces the “bow push.”

Snapping turtles only overcome the disadvantage of moving their head forward.

11-13

TONGUE FLICKING

Found in Mutiple Groups•Salamanders•Frogs•Iguanid Lizards•Tuatara•Chamaelion

In this mode of attack a sticky tongue •comes out of the mouth•“grabs” food item•pulls food into mouth

TONGUE FLICKING: How Does it Work

Salamanders

Hyobranchia contract forcing tongue forward.Similar to a kid with a mouth full of water.

Y YFig 11-21, 11-19, 11-18

TONGUE FLICKING: How Does it Work

Frogs

Muscle in front of moth contracts pulls tongue forward.Similar to a sling shot.

Fig 11-22

TONGUE FLICKING: How Does it Work

Chamelions

Hyobatrachium acts as a lever, pushes rod out, muscle at tipsquezes. Similar to a siege engine.

Fig 11-2311-24

TONGUE FLICKING: How Does it Work

Lizards

Lever pushes a rod. Chamelions modified this approach

I love these crunchy on the

outside chewy in the middle

ALL JOKING ASIDE, WHAT DOES THIS PATTERNSUGGEST ABOUT MODIFICATION OF THE

TONGUE AS A PREY CAPTURE MECHANISM?

Power Biters

•Some reptiles are specialized for powerful snapping.

•Skull is akinetic

•Turtles •No teeth•Keratinous beak•Large temporal notch

•Crocodiles•Short depressor mandibulae•Massive pterygoids, powerful adductor•Narrow Jaw Specialists•Wide Jaw Generalists•Alligators routinely eat large turtles

Fig 11-5

Kinetic Skulls•Skulls of Snakes and Lizards are highly flexible

•Allows changed in skull morphology

•Tight Fits

•“Disarticulation” of snake jaws•Mandibles connected by cartilage•Unilateral Feeding•Extreme versatility

Figs 11-29b11-3611-38

•African egg eating snakes•Large gapes•Vertebral specializations

•Hinged Teeth•Mostly skink eaters

•Pit Organs •Heat sensitive•Role in defense•Widely placed phylogenetically•Evolved to stay cool (ISU Work)

•Constriction•Specialization for killing Prey•Secondarily redeveloped in colubrids

ODD Snake Specializations

Figs 11-3711-3611-35Imager11-43

Envenomation

•Poison--delivered orally

•Venom is injected

•Three families of snakes + 1 of lizards

•Colubridae (broadly defined)

•Elapidae (cobras and kin)

•Viviparidae

•Prey restrain, digestion, and defense

11-3111-40Figs 11-41

Why Aren’t More Animals Cannibals?

•Benefits •Everything you need•Eliminate Competition

•Costs•Reproduction does you no good if you eat the results•Great way to get parasites•Prions (mad cow disease)•When should you be a cannibal?

•Steve Lima’s Work

•Being prey is game over

•Predation does more than kill 1 individual

•Trade-offs of short vs long term fitness•When to hunt, When to watch•When to call, When to hide•Temperature Performance•Safe Habitat

•Protection•Cryptic Behavior/Appearance•Be dangerous•Look dangerous (Batsman Mimicry)•Look and be dangerous (Mullein Mimicry)

How Do You Avoid Getting Eaten

Figs 15-8, 15-19e

SPEAKING OF EATING HERPSASSIMILATION EFFICIENCY SUGGESTS WE SHOULD DO SO

What besides assimilation efficiency should we consider?Does agriculture pay any attention to assimilation efficiency?

Fig 1-7