CHONDRICHTHYES

CHONDRICHTHYES 

- These are those animal which are made up of cartilage only , this mainly include dog fishes, saw fishes, sharks etc
- there is about 3,000 species in chondriochthyes
- basically animal have marine habitat
- These animal are varies in size
- Mostly animal have laterally compressed body
- Body is generally dorso-ventrally flattened
- These animal have no endosketon,
- There coelom is enterocoelous
- Their teeth may be acrodont, homodont and polyphyodont
- Their stomach is J-shaped like human
- These animal scales have placoid scales
- Respiration of this animal occur by lamelliform form
- Important thing is that their gill cover by gill cover called operculum
- Heart is about 2 chambered
- Blood have RBCs like man
- sexes are Unisexual and Show sexual dimorphism
- Cleavage is MeroBlastic
- These are aminly oviparous animal
- Fertilization External
- These animal are cold blooded animal

@ Special Feature :-

* Marine Habitat totally
* Having Two Dorsal Fin
* Heterocercal Fin
* Gill Slits Covered With cover called Operculum
* Two chambered heart
* Ear but only internal
* Clasper in male to hold female one

@ Classification :-

           Chondrichthyes are Mainly divided into two Sub-classes are
i) Elasmobranchii                                       ii) Holocephali

1. Elasmobranchii :-

          these are those fishes which have laterally compressed dorsoventrally flattened body, having placoid scales with pelvic fin and having 5-7 pair gill with operculum
* There is order in which elasmobranchii divided into as :-
- Pleurotremata :-
             these are those fishes having 5-7 gill pair with operculum ,having spindle shaped body , and having narrow base
Ex :-       Scoliodon, Zygaena (hammer headed fish)

2. Hypotremata :-

          these are those fishes which hace 5 pair gill slits, these are dorso-ventrally flat fishes and have large sized gill with operculum
EX:- Torpedo, Trygon, Raja etc

@ Economic Importance :-

- Some fish fishes like scoliodon, Rhinobatus are edible cartilagenous fishes
- These fishes have medicine importance also
- These animal having basic vertebral plan so have great evolutionary also
- Rich vitamin A and D oil are obtain by some cartilagenous fishes