BIOL108 Lecture Notes - Lecture 28: Agnatha, Chondrichthyes, Osteichthyes

• School: University of Alberta
• Department: Biology (Biological Sciences)
• Course: BIOL108
• Professor: Lien Luong

Document Summary

Nostrils function for smelling, not for gas exchange. Detect changes in electrical fields generated by muscular movement of other animals via pores around head- unique in sharks. Also detect vibrations in water via their lateral line of the body. Males have pelvic fins modified as claspers that they use to hold female and help to guide sperm internal fertilization. Within the uterus; the female holds on to the embryo until it hatches then the baby shark comes out) Viviparous (live-birth) like what humans do the egg is protected in a leathery egg case. Skeleton becomes ossified/bony replacement of cartilage by calcium phosphate. But now they are divided into 3 classes. Problem with the class osteichthyes they are paraphyletic; if restricted to fish. Because they include jawless fish, cartilaginous fish and bony fish but exclude the tetrapods (amphibians, reptiles, mammals) they would be monophyletic if they also include other classes of amphibia, reptilia and mammalia.