Difference between Chondrichthyes (cartilaginous fish) and Osteichthyes (bony fish)

Gaurab Karki — Thu, 13 Jul 2017 14:10:57 +0000

Characteristics	Chondrichthyes (Cartilaginous fish)	Osteichthyes (Bony fish)
Habitat	Mainly marine	Marine as well as freshwater
Symmetry	Usually dorsoventrally flattened	Usually bilateral symmetry
Endo-skeleton	Cartilaginous	Mostly bony
Caudal fin	Heterocrecal	Heterocercal or diphyceral
Pelvic fin	Usually posterior.	Mostly anterior, occasionally posterior.
Mouth	Large, crescent shaped on the ventral side of the head	Variable shape and size at the tip or terminal part of the head
Gill slit	Usually five pairs of gill slits which are not protected by an operculum.	Five pairs of gill slits protected by an operculum
Cloaca	A true cloaca is present	In most bony fishes, the cloaca is absent, and the anus, urinary and genital apertures open separately.
Stomach	Typically J-shaped	Shape variable. Absent in some.
Intestine	Short with spiral valve in lumen	Long with no spiral valve
Liver	Usually has two lobes	Usually has three lobes
Brain	Has large olfactory lobe, cerebrum and small optic lobe and cerebellum	Has small olfactory lobes and cerebrum and large optic lobes and cerebellum
Retina	Lacks cone cell	a pair of cone cells preesnt
Eggs	A small number of large eggs with plenty of yolk	A large number of small eggs with little yolk
Fertilisation	Internal	Usually external
Development	internally.	externally.
Examples	Scolidon, Electric ray, string ray, Sharks,	Labeo, catla, Hilsa, Wallago, Hippocampus

difference between cartilaginous fish and bony fish Archives - Online Biology Notes