Herpetology sancp2010

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PowerPoint Presentation for Great Smoky Mountain Institute at Tremont's Southern Appalachian Naturalist Certification program class on REPTILES and AMPHIBIANS

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Herpetology sancp2010

  1. 2. <ul><li>The study of amphibians and reptiles </li></ul><ul><ul><li>From the Greek: herpeton “creeping animal” </li></ul></ul><ul><ul><li>The study of ectothermic, poikilothermic, tetrapods </li></ul></ul><ul><ul><ul><li>“ Cold-blooded” is inaccurate and misleading </li></ul></ul></ul><ul><ul><ul><li>Ectothermic: An organism whose body temperature is controlled by external factors </li></ul></ul></ul><ul><ul><ul><li>Poikilothermic: An organism whose body temperature changes in concert with the ambient temperature </li></ul></ul></ul><ul><ul><ul><li>Tetrapod: An organism having 4 limbs or descended from an organism with 4 limbs </li></ul></ul></ul>
  2. 3. <ul><li>How does a reptile compare to an amphibian? </li></ul><ul><ul><li>Similarities: </li></ul></ul><ul><ul><ul><li>Four-legged, or descended from a creature with four legs </li></ul></ul></ul><ul><ul><ul><li>Ectothermic </li></ul></ul></ul><ul><ul><ul><li>Typically egg-layers, or some derivation thereof </li></ul></ul></ul><ul><ul><li>Differences: </li></ul></ul><ul><ul><ul><li>Skin texture </li></ul></ul></ul><ul><ul><ul><li>Eggs – coverings and amniotic vs. non-amniotic </li></ul></ul></ul><ul><ul><ul><li>Claws </li></ul></ul></ul><ul><ul><ul><li>Metamorphosis </li></ul></ul></ul><ul><ul><ul><li>Teeth </li></ul></ul></ul>
  3. 4. <ul><li>What is an amphibian? </li></ul><ul><ul><li>A member of the class Amphibia (Greek: amphibios “both lives” or “two lives”) </li></ul></ul><ul><ul><ul><li>Typically divides its life into two stages – aquatic and terrestrial </li></ul></ul></ul><ul><ul><ul><li>Does not refer to the ability of some animals (i.e. frogs) to move from one habitat to the other with ease </li></ul></ul></ul><ul><ul><li>Three orders </li></ul></ul><ul><ul><ul><li>Frogs (and toads) </li></ul></ul></ul><ul><ul><ul><li>Salamanders (and newts) </li></ul></ul></ul><ul><ul><ul><li>Caecilians </li></ul></ul></ul>
  4. 5. <ul><li>Natural History </li></ul><ul><ul><li>Only vertebrates to undergo metamorphosis </li></ul></ul><ul><ul><li>Obtaining oxygen </li></ul></ul><ul><ul><ul><li>Typically gills as larvae, lungs as adults, but: </li></ul></ul></ul><ul><ul><ul><ul><li>Some adults have gills </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Some adults have no lungs </li></ul></ul></ul></ul><ul><ul><ul><ul><li>All take in oxygen through mouth, throat, and skin </li></ul></ul></ul></ul><ul><ul><li>“ Cold-blooded” </li></ul></ul><ul><ul><ul><li>Ectothermic & poikilothermic </li></ul></ul></ul><ul><ul><ul><li>Move to regulate body heat </li></ul></ul></ul><ul><ul><ul><li>May spend large parts of year underground </li></ul></ul></ul><ul><ul><ul><li>Inactive in cold weather, some extremities freeze solid </li></ul></ul></ul>
  5. 6. <ul><li>Natural History </li></ul><ul><ul><li>Tetrapods </li></ul></ul><ul><ul><li>Typically smooth-skinned </li></ul></ul>
  6. 7. <ul><li>Reproduction </li></ul><ul><ul><li>Frogs </li></ul></ul><ul><ul><ul><li>Typically external </li></ul></ul></ul><ul><ul><ul><li>Sperm and eggs released at the same time into water </li></ul></ul></ul><ul><ul><li>Salamanders </li></ul></ul><ul><ul><ul><li>Typically internal </li></ul></ul></ul><ul><ul><ul><li>Males produce spermatophore from which females absorb sperm </li></ul></ul></ul><ul><ul><li>Both produce jelly-like eggs </li></ul></ul>
  7. 8. <ul><li>Frogs and Toads </li></ul><ul><ul><li>Anura – from the Latin “ without tail ” </li></ul></ul><ul><ul><li>What’s the difference between a frog and a toad? </li></ul></ul><ul><ul><ul><li>No clear cut definition in scientific uses, though there are in general use. </li></ul></ul></ul><ul><ul><ul><li>Typically more terrestrial, with shorter legs, stouter bodies, and rougher, “wartier” skin </li></ul></ul></ul><ul><ul><ul><li>Some consider toads to be a subset of frogs, so that: “Every toad is a type of frog, but not every type of frog is a toad.” </li></ul></ul></ul><ul><ul><li>3500 species worldwide </li></ul></ul><ul><ul><li>Five families in the Southern Appalachians </li></ul></ul><ul><ul><ul><li>Bufonidae – “true toads” </li></ul></ul></ul><ul><ul><ul><li>Pelobatidae – “spadefoot toads” </li></ul></ul></ul><ul><ul><ul><li>Microhylidae – “narrow-mouthed toads” </li></ul></ul></ul><ul><ul><ul><li>Hylidae – “tree frogs” </li></ul></ul></ul><ul><ul><ul><li>Ranidae – “true frogs” </li></ul></ul></ul>
  8. 9. <ul><li>Frogs and Toads </li></ul><ul><ul><li>Natural History </li></ul></ul><ul><ul><ul><li>Sexual selection based on vocalizations and sometimes territory </li></ul></ul></ul><ul><ul><ul><li>Explosive vs. prolonged breeding </li></ul></ul></ul><ul><ul><ul><ul><li>Wood frogs are explosive – all members of a population breed at once (within a few days or even hours) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>American toads are prolonged – breeding is spread over a longer period of time </li></ul></ul></ul></ul><ul><ul><ul><li>Larvae </li></ul></ul></ul><ul><ul><ul><ul><li>Tadpole (Middle English for “toad’s head”) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>aka “pollywog” (“wiggling head”) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Internal gills </li></ul></ul></ul></ul><ul><ul><ul><ul><li>No legs (in first stages) </li></ul></ul></ul></ul>
  9. 10. <ul><li>Frogs and Toads </li></ul><ul><ul><li>Natural History </li></ul></ul><ul><ul><ul><li>Larvae </li></ul></ul></ul><ul><ul><ul><ul><li>Most are “suspension feeders” filtering plankton, algae, etc. from the water </li></ul></ul></ul></ul><ul><ul><ul><ul><li>May root around in leaf litter or scrape surface of rocks with tooth-like structures </li></ul></ul></ul></ul><ul><ul><ul><li>Defense </li></ul></ul></ul><ul><ul><ul><ul><li>Camouflage </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Leaping </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Noxious or toxic secretions </li></ul></ul></ul></ul>
  10. 11. <ul><li>Frogs and Toads </li></ul><ul><ul><li>Natural History </li></ul></ul><ul><ul><ul><li>Morphology </li></ul></ul></ul><ul><ul><ul><ul><li>Dorsolateral ridges </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Tympanum </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Parotoid glands (mostly toads, but some frogs and salamanders) </li></ul></ul></ul></ul><ul><ul><ul><li>Vocalizations </li></ul></ul></ul><ul><ul><ul><ul><li>Advertisement – most obvious </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Aggressive </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Courtship </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Release </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Defensive </li></ul></ul></ul></ul>
  11. 12. <ul><li>Salamanders </li></ul><ul><ul><li>Caudata – from the Latin for “ with tail ” </li></ul></ul><ul><ul><ul><li>Some use Urodela (Greek, “ tail visible” to refer to extant species, and Caudata to refer to all salamanders) </li></ul></ul></ul><ul><ul><li>420+ species worldwide </li></ul></ul><ul><ul><li>Five families in the Smokies </li></ul></ul><ul><ul><ul><li>Cryptobranchidae – eastern hellbender </li></ul></ul></ul><ul><ul><ul><li>Plethodontidae – lungless salamanders </li></ul></ul></ul><ul><ul><ul><ul><li>Largest family worldwide, most species in N. America </li></ul></ul></ul></ul><ul><ul><ul><li>Ambystomidae – mole salamanders </li></ul></ul></ul><ul><ul><ul><li>Salamandridae – red-spotted newt </li></ul></ul></ul><ul><ul><ul><li>Proteidae – common mudpuppy </li></ul></ul></ul>
  12. 13. <ul><li>Salamanders </li></ul><ul><ul><li>Natural History </li></ul></ul><ul><ul><ul><li>Carnivorous </li></ul></ul></ul><ul><ul><ul><li>Defense </li></ul></ul></ul><ul><ul><ul><ul><li>Autotomy </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Break can occur between vertebrae in some species, while most breaks occur within vertebrae </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Sphincter muscles </li></ul></ul></ul></ul></ul>
  13. 14. <ul><li>Salamanders </li></ul><ul><ul><li>Natural History </li></ul></ul><ul><ul><ul><li>Defense </li></ul></ul></ul><ul><ul><ul><ul><li>Skin secretions </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Toxic </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Sticky </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><li>Camouflage </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Mimicry </li></ul></ul></ul></ul><ul><ul><ul><li>Mate selection </li></ul></ul></ul><ul><ul><ul><ul><li>Tail (and other) displays </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Pheremones </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Scat-sniffing </li></ul></ul></ul></ul><ul><ul><ul><li>Internal fertilization </li></ul></ul></ul><ul><ul><ul><ul><li>Males leave behind a spermatophore (sperm packet) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Females pick up packet through cloaca </li></ul></ul></ul></ul>
  14. 15. <ul><li>Salamanders </li></ul><ul><ul><li>Natural History </li></ul></ul><ul><ul><ul><li>Typical life cycle </li></ul></ul></ul><ul><ul><ul><ul><li>Egg, larvae, juvenile, adult </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Egg and larvae are aquatic, juvenile and adult terrestrial </li></ul></ul></ul></ul><ul><ul><ul><li>Non-typical life cycles </li></ul></ul></ul><ul><ul><ul><ul><li>All terrestrial – no aquatic larval stage, hatchlings look just like miniature adults </li></ul></ul></ul></ul><ul><ul><ul><ul><li>All aquatic – adults remain fully aquatic, sometimes retaining larval features </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Newts – aquatic as larvae, terrestrial as juveniles (“eft” stage,) aquatic as adults </li></ul></ul></ul></ul>
  15. 16. <ul><li>Salamanders </li></ul><ul><ul><li>Natural History </li></ul></ul><ul><ul><ul><li>Larvae </li></ul></ul></ul><ul><ul><ul><ul><li>External gills </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Legs </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Tail typically more keeled than adults </li></ul></ul></ul></ul><ul><ul><ul><li>Juvenile </li></ul></ul></ul><ul><ul><ul><ul><li>Resemble miniature adults </li></ul></ul></ul></ul><ul><ul><ul><ul><li>No eyelids </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Thinner skin </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Not sexually mature </li></ul></ul></ul></ul>
  16. 17. <ul><li>Salamanders </li></ul><ul><ul><li>Natural History </li></ul></ul><ul><ul><ul><li>Morphology </li></ul></ul></ul><ul><ul><ul><ul><li>Appear much like lizards, but: </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>No scales, claws, or teeth </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><li>4 toes in front, 5 in back </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Costal grooves </li></ul></ul></ul></ul>
  17. 18. <ul><li>What is a reptile? </li></ul><ul><ul><li>A member of the class Reptilia (Latin: reptilis “creeping”) </li></ul></ul><ul><ul><li>Four orders </li></ul></ul><ul><ul><ul><li>Lizards and snakes </li></ul></ul></ul><ul><ul><ul><li>Turtles </li></ul></ul></ul><ul><ul><ul><li>Crocodilians </li></ul></ul></ul><ul><ul><ul><li>Tuataras </li></ul></ul></ul><ul><li>Natural History </li></ul><ul><ul><ul><li>Ectothermic </li></ul></ul></ul><ul><ul><ul><li>Tetrapods </li></ul></ul></ul><ul><ul><ul><li>Scaly skin </li></ul></ul></ul><ul><ul><ul><li>Lungs </li></ul></ul></ul>
  18. 19. <ul><li>Reproduction </li></ul><ul><ul><li>All have internal fertilization </li></ul></ul><ul><ul><ul><li>Hemipenis – two sided, but only one side is used at a time </li></ul></ul></ul><ul><ul><li>Eggs are leathery </li></ul></ul><ul><ul><li>Birth </li></ul></ul><ul><ul><ul><li>Viviparous (live birth) </li></ul></ul></ul><ul><ul><ul><ul><li>Technically a subtype called “ovoviviparous,” as the embryos develop within eggs in the mother’s body (as opposed to a womb) </li></ul></ul></ul></ul><ul><ul><ul><li>Oviparous (egg layers) </li></ul></ul></ul><ul><ul><ul><li>All reptiles are independent from birth, but that does not mean that they do not receive parental care </li></ul></ul></ul>
  19. 20. <ul><li>Turtles </li></ul><ul><ul><li>Order Testudines – from the Latin testa , “shell” </li></ul></ul><ul><ul><li>300+ species worldwide </li></ul></ul><ul><ul><li>Four families in the Southern Appalachians </li></ul></ul><ul><ul><ul><li>Chelydridae – snapping turtles </li></ul></ul></ul><ul><ul><ul><li>Emydidae – box and pond turtles </li></ul></ul></ul><ul><ul><ul><li>Kinosternidae – mud and musk turtles </li></ul></ul></ul><ul><ul><ul><li>Trionychidae – softshell turtles </li></ul></ul></ul><ul><ul><li>Common ancestor shared with other reptiles is very ancient – some argue that turtles belong in a completely separate group </li></ul></ul>
  20. 21. <ul><li>Lizards </li></ul><ul><ul><li>Natural History Morphology </li></ul></ul><ul><ul><ul><ul><li>External ear openings, nostrils, and (typically) eyelids </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Jacobson’s organ (more highly developed in squmates than in most other animals, though snakes have the most highly developed of all) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Legless lizards retain lizard-like characteristics and have pelvic structures, though they are greatly reduced </li></ul></ul></ul></ul>
  21. 22. <ul><li>Turtles </li></ul><ul><ul><li>Natural History </li></ul></ul><ul><ul><ul><li>Morphology </li></ul></ul></ul><ul><ul><ul><ul><li>Color vision, excellent night vision </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Shell </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Upper ‘carapace’ </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Lower ‘plastron’ </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Individual pieces are scutes, which are shed periodically </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Ribs and vertebrae are integral parts </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>One can often sex turtles based on concavity of plastron </li></ul></ul></ul></ul></ul>
  22. 23. <ul><li>Turtles </li></ul><ul><ul><li>Natural History </li></ul></ul><ul><ul><ul><li>Behavior </li></ul></ul></ul><ul><ul><ul><ul><li>Can make noises, but lack vocal chords </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Basking </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Body temperature regulation (ectotherms) </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Encouraging parasites to drop off </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Reduce algal growth </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Vitamin D </li></ul></ul></ul></ul></ul>
  23. 24. <ul><li>Lizards and Snakes </li></ul><ul><ul><li>Order Squamata – from the Latin for “scale” </li></ul></ul><ul><ul><ul><li>Squamata is further divided into suborders Iguania and Scleroglossa. Sclerglossa contains the suborder Autarchoglossa (and others such as Gekkota). Autarchoglossa contains the suborders Serpentes and the infraorders Scinicomorpha and Anguimorpha. </li></ul></ul></ul><ul><ul><li>Suborder Iguania </li></ul></ul><ul><ul><ul><li>2 families in the Smokies </li></ul></ul></ul><ul><ul><ul><ul><li>Polychrotidae – anole </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Phrynosomatidae – fence lizard </li></ul></ul></ul></ul>
  24. 25. <ul><li>Lizards and Snakes </li></ul><ul><ul><li>Suborder Autarchoglossa </li></ul></ul><ul><ul><ul><li>Infraorder Anguimorhpa </li></ul></ul></ul><ul><ul><ul><ul><li>1 family in the Park </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Anguidae – glass lizard </li></ul></ul></ul></ul></ul><ul><ul><ul><li>Infraorder Scincomorpha </li></ul></ul></ul><ul><ul><ul><ul><li>2 families in the Park </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Teiidae – racerunner </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Scincidae – skinks </li></ul></ul></ul></ul></ul><ul><ul><ul><li>Suborder Serpentes </li></ul></ul></ul><ul><ul><ul><ul><li>2 families in the Park </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Viperidae – copperhead and timber rattlesnake </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Colubridae – all the rest </li></ul></ul></ul></ul></ul>
  25. 27. <ul><li>Snakes </li></ul><ul><ul><li>Order Squamata </li></ul></ul><ul><ul><ul><li>Suborder Scleroglossa </li></ul></ul></ul><ul><ul><ul><ul><li>Suborder Autarchoglossa </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Suborder Serpentes </li></ul></ul></ul></ul></ul><ul><ul><li>2700+ species worldwide </li></ul></ul><ul><ul><li>Evolved lack of limbs from a common ancestor in a separate evolutionary line than legless lizards </li></ul></ul><ul><ul><li>The family Colubridae make up some 2/3 of modern snake species worldwide </li></ul></ul>
  26. 28. <ul><li>Snakes Natural History - Morphology </li></ul><ul><ul><ul><ul><li>Highly developed Jacobson’s organ, with stereo scent detection </li></ul></ul></ul></ul><ul><ul><ul><ul><li>6 rows of teeth </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>2 on top jaw </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>2 on bottom jaw </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>2 on roof of mouth </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Sharp and curved backwards </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Vary between species, allowing specific teeth to function in special ways, including injecting or channeling venom </li></ul></ul></ul></ul></ul>
  27. 29. <ul><li>Snakes Natural History - Morphology </li></ul><ul><ul><ul><ul><li>Skin sheds in one piece as they grow, referred to as “ecdysis” </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>New layer forms beneath old </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Fluid from lymphatic system spreads between layers </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Eye turns milky from the liquid that fills underneath the clear scale that covers it </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Does NOT happen on a yearly basis, contrary to popular belief </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><li>Heat sensing pits – family Viperidae only </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Some colubrids have venom and fangs </li></ul></ul></ul></ul>
  28. 30. <ul><li>Snakes Natural History Morphology </li></ul><ul><ul><ul><ul><li>The pattern of scales on the body is unique to each species, so it can be used to determine whether or not a snake is venomous, or to use a shed skin to identify a species </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Venomous vs. Non-venomous </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Head shape (can be confusing) </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Facial pits (works here in the mountains where all of our venomous snakes are pit vipers, but not elsewhere with other snakes such as coral snakes or cobras) </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Elliptical vs. circular pupil (again, works with our venomous snakes but not with others, and you must be fairly close) </li></ul></ul></ul></ul></ul>
  29. 31. <ul><li>Snakes - Natural History - Morphology </li></ul><ul><ul><ul><ul><li>Venomous vs. non-venomous </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Scales posterior to cloaca – paired in non-venomous snakes, single in venomous (must be really close, and again, not consistent) </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Know the venomous snakes in your area! </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><li>Rattles </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Rattlesnakes are born with just a “button” (one layer of the rattle, unable to produce a noise,) each time the snake sheds it obtains another layer </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>The noise is not produced by a “bead” inside a hollow structure (like a child’s toy) but rather by loosely connected layers within a stack hitting each other as the tail vibrates </li></ul></ul></ul></ul></ul>
  30. 32. <ul><li>Snakes - Behavior </li></ul><ul><ul><ul><li>Movement </li></ul></ul></ul><ul><ul><ul><ul><li>Lateral undulation – most North American snakes. Pushing off the ground or vegetation with many points of contact, propelling it forward. Sidewinding is a version in which parts of the body are lifted off the ground and moved forward and sideways. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Rectilinear motion – big, heavy snakes. Pulling belly scales across the ground. Almost like an inchworm, but with very, very small “arcs” between points of contact. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Concertina – body compresses into small arcs laterally, then straightens. </li></ul></ul></ul></ul>
  31. 33. <ul><li>Snakes - Feeding </li></ul><ul><ul><ul><li>All are carnivorous </li></ul></ul></ul><ul><ul><ul><ul><li>Envenomation </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Viperids have long, hollow teeth located on a short maxillary bone at the front of the mouth that can rotate back and forth. When not in use, the fangs can therefore rotate back out of the way. </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Elapids (family Elapidae – cobras, corals, mambas) have fixed, hollow fangs, also at the front of the mouth. </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Venomous colubrids (of which there are very few) possess grooved fangs in the middle of the mouth (often referred to as “rear-fanged snakes”) that deliver a typically mild venom that flows down the grooves in the teeth </li></ul></ul></ul></ul></ul>
  32. 34. <ul><li>Snakes - Feeding </li></ul><ul><ul><ul><li>All are carnivorous </li></ul></ul></ul><ul><ul><ul><ul><li>Envenomation </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Constriction </li></ul></ul></ul></ul><ul><ul><ul><ul><li>The Teenager – grabbing food and immediately swallowing it – no chewing! </li></ul></ul></ul></ul><ul><ul><li>Reproduction </li></ul></ul><ul><ul><ul><li>Oviparous </li></ul></ul></ul><ul><ul><ul><li>Viviparous – technically ovoviviparous </li></ul></ul></ul>

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