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?