BIOL108 Lecture Notes - Lecture 28: Shark Tooth, Filter Feeder, Fish Scale

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

Document Summary

Myxini have a head but not a vertebral column. A chain of skeletal elements surrounding and protecting the nerve cord. Subphylum vertebrata have a more complex nervous system. The vertebrate replaces the function of the notochord. It provides rigidity, and provides an attachment site for muscles and other skeletal elements. Eyes with lenses, but no jaws or paired limbs. Paired dorsal spines from tube partially enclose nerve cord. Lampreys are parasites of sh, and adults live mainly in lakes or oceans. They feed o the scales and esh of the sh with the spikes on their mouth. They clamp on to the side of the sh and rasp away with tongue (keratin spikes). When not feeding, they often hold onto rocks with their oral sucker. Gnathostomes: jawed sh evolved 450 million years ago. 2 pairs of ns evolved, extinct agnathans (jawless)- 1 pair, extant agnathans- no paired.