EEB267H1 Lecture Notes - Lecture 6: Osteichthyes, Endochondral Ossification, Fish Scale
5 Sep 2015
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Extremely diverse (32, 000 species) because of: gas bladder, modified jaw, diverse reproductive modes, diverse types of parental care, heavy ganoid scales replaced w/ lighter, flexible scales for most fish, bichir and sturgeon still have (older groups, made of collagenous plates with hypermineralized edges, edges laid down in successive rings, can use to age fish. But bit heavier because calcium salts (1) cartilaginous endoskeleton light (2) stay on bottom (some sharks, skates, rays) (3) liver full of lipids: make them more buoyant in salt water, neutralizes weight of cartilage endoskeleton. Bone does not function well in extreme pressure: osteoblasts don"t function = biomechanical property (3) swim continuously (tuna, marlin) (4) stay at bottom (benthic like sturgeon, sole) (5) gas bladder (most common) Suction feeding: dominant mode, approach/orient towards prey/wait for prey to come (stealth) (1) expand oral cavity, open jaws, lower and move supsensorium backwards and out.
