Biodiversity

Tuesday, May 16, 2006

MORPHOLOGICAL DIFFERENCES BETWEEN CARTILAGINOUS AND BONY FISH

Cartilaginous and bony fishes falls under the kingdom animalia. Vertebrates are organism that contains a back bone and all fishes contains a back bone which means that they are all vertebrates. The morphological structure of the two fishes is totally different. They are both very rough but catilaginous is more rougher.

Cartilaginous fishes are so called because of their lack of the real bone even though their bodies consist of a cartilage. "The cartilaginous fishes have strong jaws. The mouth of the cartilaginous fish is found underside of the head, while the eyes are found on top of the head. Cartilaginous fishes also possess the two nostrils which are used for smelling. They can not see food as it enters their mouth. Some Shark solve this problem by touching their food with their nose before they eat. Some use powerful electro sensory system. Sharks, Skates and rays have rough skin. Sharks have five to seven gills slits on each side of their head. But bony fishes have 1 gill on each side. Chimaeras or Gost shark have skins that are very smooth and have only one pair of external gill openings. Cartilage fish give live birth through their bodies, they prefer internal reproduction whereas bony fishes reproduce by laying eggs. Cartilages prefer water with high salt quantity only while bony fishes survive in all types of salt" (1)

"Bony fishes are very common and their example include gurnard and snapper. Bony fish are classified into Lobe finned and the Ray –finned. Lobe-finned bone fish includes fish such as lungfish and coelacanth’s, where as Ray-fins includes the goldfish, tuna, and trout. They contains a tail fin which is equal in both the proportion bottom and top. They have a bony skeleton and single pairs of external gill openings. The mouth is generally at the front of the body. It has relatively short tube. Bony fish reproduce by external fertilisation of eggs and releases them into water. The male releases sperm called Milt into water. Milt combines with the eggs and fertilisation takes place" (1)

Their liver is filled with oils which keep them from sinking. They have internal fertilisation. The bones of fish are made mostly by calcium but Shark does not have any bones. Shark skeleton is made of cartilage, and have no bladder, but bony fish have a gas filled swim bladder which enables them to float in the water. Bony fish have movable parts were as shark does not have. Shark can turn around in a smaller space than bony fish.The brain of the ghost sharks is closely related to that of the birds and mammals. As compared to that of the bony fish, the brain of the cartilaginous is ten times to that of the bony fish. While the brain size of the bony fish is thought to closely relate to that of the human beings, the reason of having such a big brain because they use a lot of energy.

Reference

1. Studios, A.R. 1997 Biology for kids vertebrates fish [Internet]. [Cited 2006 May 16] Available from:http://www.biology4kids.com/files/vert_fish.html[2006

2. The wikipedia contributor, Cartilaginous [Internet] Wikipedia, The free encyclopaedia; 2006 May 16; 16:13 UTC [Cited 2006 May 16] Available from:
http://en.wikipedia.org/wiki/Cartilaginous


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