BIOL-K - Biology BIOL-K 103 Lecture Notes - Lecture 13: Agnatha, Swim Bladder, Yolk
27 Apr 2016
School
Department
Professor
Document Summary
Chordates: vertebrates: cartilaginous or bony vertebrae encloses nerve cord, pronounced cephalization, brain is enclosed/protected by a cranium, neural crest cells influence development of many structures nerves, head muscles, cranium, jaws. System include closed circulation, digestive, endocrine glands, endoskeleton, excretory. Six are fish jawless and jawed fishes. Class myxini: hagfishes: habitate marine only, only craniate isosmotic with salt water. Cranium limited and cartilage: no paired fins, notochord as adults. Feeding scavengers: defense secretes slim (covers gills of attacking fish , fish retreat or may die from lack of oxygen) Jawless fish: lampreys: oldest living vertebrate lineage, habitat: marine, freshwater, and estuaries. Vertebral column primitive, cartilage rod next to notochord with extensions similar to vertebrae which partially enclose nerve cord. Jaws a specialization of gill arches, could ingest solid food. Cartilaginous fishes (class chondrichthyes: members: sharks, skate and rays (most marine) Scales: placoid: mouth: ventral, gills: opening, sharks: lateral, rays and skates: ventral.
