BIOL 3340 Herpetology Lecture 1 Foul and Loathsome Creatures PDF

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Herpetology Lecture 1: Foul and Loathsome Creatures Herpetology ● An artificial grouping of amphibians and reptiles ● 2 big groups of animals not related to each other at all ● 2 major clades ○ Lissamphibians ○ Amniota ○ Leave mammals and birds out Similarities ● Herpetology - from greek meaning “to creep” ● Furless and hairless organisms ● We sample them the same way ● Use organisms a lot in biology as model organisms ○ Great for toxicology Amphibians and Reptiles in Research ● External development ● Development of herpetiles depend on ○ Temperature ■ Dependant reptiles may be affected by temp changing their sex ■ Males prefer a certain temp as an egg vs females ○ Predator presence ■ 100 hours for tadpoles to hatch without predators ■ When there was a predator introduced to the environment, the larva would hatch 15 hours earlier ■ When fish are present, the tadpoles hatched even faster to swim away ■ When they hatch, depending on the predator, the movement of the tadpoles change for survival ○ Destiny ○ Contaminants ■ Roundup prevented the tadpoles from metamorphosing Devonian ● 417 million years ago ○ Tetrapods appeared ● Surface of the earth is dry and rocky ● Most of the life is found in the oceans at this time ● Age of fish! Late devonian ● More water over the landscape ● Period of time where you start to see fish with large lobes and fins staring to evolve ● Fish had lungs before they moved to land ○ Believed to develop them to survive in waters that were found to be anoxic Early tetrapods ● Had lung breathing organisms ● Some species were becoming more elongated ○ Heads longed out and eyes changed ○ Larger pectoral girdles being found ○ A lot of limbs that were starting to get digits

○ Started to see wrists and bending going on Tiktaalik ○ Coolest species ○ Still had fins ○ Developed wrists ○ Developed pelvic girdles ○ Ichthyostega had fingers, limbs and hands but no weight bearing bones ■ Meaning they didnt go on land but they used their fingers to navigate shallows IMPORTANT ● Skeletal ○ Effects of gravity on the skeletal system ○ Increased size of muscles, vertebrate, limbs, and pectoral a pelvic girdles (lighter skulls) ● Respiratory ○ Gills collapse out of water ○ Need gas exchange from skin, buccopharynx and lungs ● Reproduction ○ Embryos need moisture for development - need to stay close to water r evolve alternatives (eggs, womb) ● Skin ○ Thicker ○ Keratinized outer layer to resist abrasion and desiccation ○ Mucous producing glands Amphibia ● One of the first clades to diverge from tetrapods ● Presented as caecilians, salamanders, and frogs Lissamphibia ● Common organism from amphibia ○ Gerobatrachus ○ Gymnopiona ■ Most ancestral ■ Latin word caecus meaning blind ■ Mainly tropical ■ Legless ■ Burrowing and aquatic forms of this Caudata (salamander) ● Over half of all species dont have lungs ● Use gills, lungs and skin fr respiration ● 10 extendant families ● Larvae and adults have tails Anura (frogs) ● Most identifiable ● Legs tend to be twice their body length ● High biodiversity in the tropics ● ⅔ of them are found in 4 families ○ Leptodactylidae ○ Hylidae ●

○ Ranidae ○ Bufonidae Carboniferous - era of insects ● Most things evolve out of the water ● Reptiles developed the ability to produce eggs Anthracosaur ● Give rise to our current fijis Amniotes ● They use skulls a lot to differentiate animals ● Holes in the skull help with determining animals too ● Does not work for herps as most of them dont have holes in their head Reptilian features ● Epidermis (scales, feathers) ● Keritinized epidermis (protects from drying out, abrasion) ● Nerve ending have extended tips ● Most features are in the skull ● Egg laying Birds are reptiles too Crocodylia - crocodiles ● Their evolution did not change much ● Mostly in tropical regions ● Mostly freshwater, some brackish or marine ● Strong flexible invertebrate ● Heavily armored, elongate body Sphenodontia - Tuatara ● Sister to lizards ● Very similar to lizards ● In mesozoic era, more abundant than squamata Squamata ● Lizards, snakes and amphisbaenians ● Have adapted to everything but permafrost regions...