FEEDING ECOLOGY OF AMPHIBIANS AND REPTILES
When you are hungry what do you do?
1. Dig out wallet/open fridge
2. Decide what you want/can eat
3. Capture Food Item
4. Cook Food Item
5. Consume Food Item
6. Digest
7. 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 Cost
2. Decide what you want/can eat—Limitations of Cost
3. Capture Food Item—Often the major cost
4. Cook Food Item
5. Consume Food Item—Not as easy as it sounds
6. Digest—another big cost
7. Repeat—When and how much
8. Hope Nobody Eats You—A REALLY BIG COST
9. 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 Flora
Rotting in the Gut—Cold Temperatures
Successful Herbivores:
Iguanas, 2 Other Lizards
Tadpoles (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 Water
2. Primitive: How Most Bony Fish Eat
3. Difficult to Do Without Gill Slits
Specializations for Feeding
Suction 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
Figs 11-1b
Water flow is now 2 directional.
How is this a problem?
Now suction gives the predator a brief advantage,
or at least reduces the “bow push.”
11-13
Snapping turtles only overcome the disadvantage of moving
their head forward.
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
Fig 11-21, 11-19, 11-18
Hyobranchia contract forcing tongue forward
Similar to a kid with a mouth full of water.
Y
Y
TONGUE FLICKING:
How Does it Work
Frogs
Fig 11-22
Muscle in front of moth contracts pulls tongue forward.
Similar to a sling shot.
TONGUE FLICKING:
How Does it Work
Chamelions
Fig 11-23
11-24
Hyobatrachium acts as a lever, pushes rod out, muscle at tip
squezes. Similar to a siege engine.
TONGUE FLICKING:
How Does it Work
Lizards
I love these
crunchy on the
outside chewy in
the middle
Lever pushes a rod. Chamelions modified this approach
ALL JOKING ASIDE, WHAT DOES THIS PATTERN
SUGGEST 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 11-29b
11-36
11-38
ODD Snake Specializations
•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
Figs 11-37
11-36
11-35
Imager
11-43
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
11-31
11-40
Figs 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?
How Do You Avoid Getting Eaten
•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)
Figs 15-8, 15-19e
SPEAKING OF EATING HERPS
ASSIMILATION EFFICIENCY SUGGESTS WE SHOULD DO SO
Fig 1-7
What besides assimilation efficiency should we consider?
Does agriculture pay any attention to assimilation efficiency?