Zusammenfassung der Ressource
Chondricthyes - Cartilaginous Fish
- Paleozoic Radiation
- Amphystylic jaw support
- Chondrocranium fixed to palatoquadrate
- Body supported - Notochord +
neural arches and cartilage
- Paired fins - fixed (no rotation)
- Limited scales
- 3 cusped teeth
- Tooth whorl - lots of new
teeth developing, rotation to
the front then falling out
- present in all extant sharks
- Mesozoic Radiation
- Hybodonts
- Heterodont dentition - posterior teeth
- In batteries - several teeth whorl
- Pectoral fins rotate - not fixed
- Ceratotrichia
- Proteinaceous flexible fin rays
- Curve base to tip and front to back
- Produce lift and stability -
greater thrust and counteract
sinking
- Amphistylic jaw support
- Terminal mouth
- Extant radiation - sharks skate and rays (elasmobranchs)
- Solid, calcified vertebrae
- thicker, complex enamel teeth
- Ventral mouth - overhanging rostrum
- From Triassic and earlier. Jurassic and cretaceous genera still here
- ~815 spp - all marine
- Cartilaginous skeleton
- Tails
- Heterocercal - vertabrae extend into lobe
- Epicercal - Upper caudal lobe larger
- Hypocercal - Lower caudal lobe larger
- Placoid scales - modified to form teeth
- Lateral line system - sensory
- Ampullae of Lorenzini
- Electroreceptors in head and pectoral fins
- Pits below epidermis containing conductive glycoprotein
- SHARKS
- ~360 spp 2 lineages(poss4+)
- SQUALOIDS (basking sharks, megamouth)
- Deep cold water
- GALEOIDS (Requiems, hammerheads)
- warm shallow seas
- Hyostylic Jaw Suspension
- Cranial kinesis. Elastic ligaments
- Platoquadrate teeth - recurved, stout, highly serrated
- Reproduction
- Internal fertilisation
- Small numbers - well
provisioned offspring
- Lecithotropy - yolk in egg
- Matrotrophy - reproductive tract
- Oviparous - mermaid's purse
- Ovoviparous - egg retention, eggs
move to uterus, hatch & stay
- Milky substance in uterus, pass through offsprings' mouth and gills for nourishment.
- BATOIDS (skates and rays)
- Skates - thick, paired dorsal fins,
caudal fin, oviparous
- Rays - whiplike, serrated
dorsal barbs, viviparous
- ~456 spp -early divergence from sharks
- Dorsoventrally flattened - bottom dwellers
- Generating electricity
- intracellular fluid 84mV -ve extracellular. Na+ exclusion. Smooth surface
depolarises. Rough surface stays -84mV. Na+ flows -> +67mV
- Teeth - flat crowned plates
- Specialised mouth - mollusc and crustacean diet
- enlarged pectoral fins - thrust
- HOLOCEPHALIANS
- ~35spp
- diverged from sharks ~360mya
- Anatomically odd mix
- Shark like & boney fish
- ground dwelling, deep water.
- Autostylic jaw - mixed diet, fused tooth plates
- Oviparous - cephalic claspers
- poisonous spines