OSTEICHTHYES

OSTEICHTHYES

- These are those fishes which are bone as their part of their endoskeleton, these fishes also called "bony fishes"
- Systamatic position of this fishes are Vertebrata> Gnathostomata> Pisces> Osteichthyes
- These animal are mostly aquatic animal
- These animal have spindle shaped body for easy swimming in water
- These animal have paired pectoral and pelvic fin
- As name suggest they have endoskeleton made up of bone
- There coelom is enterocoelus type
- Body Covered by cycloid scale
- Teeth of animal are homodonnt, acrodont and polyphodont type
- Having four pair of filliform gill
- Heart is two chambered
- Ear is internal only
- These animal have branchial respiration
- These are oviparous animal
- Sexes are separate in this animal
- Fertilization are external in this animal
- These animal have cold-blooded animal
- They are ammonotelic animal
- Having 10 pair of cranial nerve
- having Tail fin

@ Special Character :-

* Having exoskeleton of ganoid, Ctenoid or cycloid scales
* Ammonotelism
* Gill have OperCulum
* Two Chambered heart
* Presence of swim bladder to maintain specific gravity in water

@ Classification :-

       Osteichthyes can be divided into two main sub classes are
- Actinopterygii                       - Sarcopterygii

i) Actinopterygii :-

         * these are ray finned fishes
* Air bladder as Hydrostatic organ
* Further Divided into classes are

~ Chondrostei :-

         these animal having ganoid scale,heterocercal tail fin, and endoskeleton by cartilage
Ex:- Polypterus, Acipenser

~ Holostei :-

            these animal having wheather ganoid or cycloid scale with Hemiheterocercal tail and their endoskeleton is moderately Ossified
Ex:- Lepisostens, Amia

~ Teleostei :-

        these animal have wheather cycloid or ctenoid scales, with homocercal fin with largely ossified endoskeleton
Ex :- Syngnathus, Mystus etc

@ Advancement :-

* Development of bony endoskeleton
* streamlined body prevent less resistance by water current
* Having Swim bladder to maintain specific gravity
* Osmoregulation
* having Brain

@ Economic Importance :-

- These animal taken as food
- From These animal Liver oil also extracted
- Certain fishes like Gambusia help in controlling malaria , this fish usually eat larva
- Medicine importance also shown by these fishes
- Evolutionary importance for studying some evolutionary fundmental