Monday, March 12, 2012

Comparison between cartilaginous and bony fishes


Cartilaginous fishes (Chondricthyes)
Bony fishes (Osteichthyes)
1.        Exclusively marine.
Marine & fresh water.
2.        Heterocercal caudal fin.
Homocercal caudal fin.
3.        Cartilaginous endoskeleton.
Bony endoskeleton
4.        Gill slits without operculum.
4 pairs of gills covered by an operculum on each side.
5.        Crescent (half moon) shaped ventral mouth
Terminal mouth
6.        Skin with placoid scales. Teeth are modified placoid scales which are backwardly directed.
Scales are Cycloid, ctenoid etc.
7.        No air bladder so they have to swim constantly to avoid sinking.
Air bladder for buoyancy
8.        Sexes are separate. In males pelvic fins bear claspers.
Sexes are separate. No claspers
9.        Internal fertilization.
Fertilisation external
10.     Many of them viviparous
Mostly oviparous
11.     E.g. Scoliodon (Dog fish), Pristis (Saw fish), Carcharodon (Great white shark), Trygon (Sting ray), Torpedo (Electric ray)
E.g.
Marine fishes: Exocoetus (flying fish), Hippocampus (sea horse), Sardine, Mackeral, Tuna, Remora (sucker fish), Pomfret, Cybium              
Fresh water fishes: Labeo (Rohu), Catla (Katla), Clarias (Magur), Tilapia, Anabas (Climbing perch)              
Aquarium fishes:
Betta (Fighting fish), Pterophyllum (Angel fish) etc.


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