Lecture 22 - Vertebrata - Fish (Cont.)

Lecture 22 - Vertebrata - Fish (Cont.) - they can fill with...

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Lecture 22 – Cont. D. Actinopterygii (Osteichthyes) – class name o the bony, ray-finned fish (thin fin, not fleshy looking) Freshwater, marine (fig. 31-13) o the largest class of vertebrates in numbers of individuals and different kinds of species Evolution o adnatha *includes ostracoderms) – ancient fishes these are the most ancient – no jaws, un paired finds, cartilaginous The cephalospidomorphi (lampreys) – another ancient species Ostrachaderms – now extinct, they evolved into the placoderms o placoderms – now extinct, first group with jaws, mostly cartilaginous, paired fins (now they are active predetors), Gave rise to three big groups: 1) chondrichthyes – (sharks); cartilaginous fish 2) Actinopterygii – ray-finned (modern-day bony fish); has a swim bladder that
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Unformatted text preview: they can fill with gas for buoyancy 3) Sarcopterygii – lung fishes, lobe-finned fishes, fleshy fins (bony); gave rise to 2 groups: 1) Diphoi – lung fish; evolved into the amphibians (more closely related to us 2) Actinistin – lobe-finned fish (coelacanth) • Bony skeleton – (NOT CARTILEDGE) most more resistant to damage (can protect the head area) • Bony dermal scales – provides protection • Operculum – external gill slits: operculum is a bony flap that protects the gills, it is also flapped by muscles to move water through gills • Heart – 2 chambers • Reproduction – external fertilization, oviparous (egg-layer)...
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Lecture 22 - Vertebrata - Fish (Cont.) - they can fill with...

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