ZOO 2090 Lecture Notes - Lecture 9: Fossorial, Internal Fertilization, Isometry

• School: University of Guelph
• Department: Zoology
• Course: ZOO 2090
• Professor: Jinzhong Fu

Document Summary

Groups: anurans (frogs and toads)(cid:198)most diverse group, caecillians(cid:198)earth worm like, live only in tropical areas. Integument: mucous glands(cid:198)secrete mucus which helps with respiration, granular glands secrete poisonous alkaloid compounds involved in defense. Skin is thin which allows for gas exchange(cid:198)but the more terrestrial the more keratinized the integument is: this helps against desiccation, only some caecilians and toads have bone elements in the dermis. Metamorphosis: metamorphosis(cid:198)change in morphology, amphibians have 2 life stages(cid:198)adult and larvae. Larvae live in water (with gills) and adults are terrestrial (lungs) Tooth has structure dividing base (pedicel) from tip (crown: unique to amphibians in modern forms(cid:198)but also seen in some temnospondyls, a(cid:198)salamander, b(cid:198)caecilian. Anurans (order anura: main characters, absence of tail(cid:198)only in adults, tympanum usually present(cid:198)eardrums. Jumpers exposed on skin: fertilization external (except in ascaphus, have specialized skulls and skeletons. Skull: flattened, open with big jaws, palate is highly reduced, allowing the eyeballs to drop into the oral cavity.