SCOLIODON
The Chondrichthyes are also known as elasmobranchs. They are almost exclusively marine and include sharks, rays, and chimaeras. Scoliodon is an elasmobranch which is marine and is an active swimmer. Scoliodon is widely studied shark all over the world. The genus is represented by nine species, of which four are very common in Indian seas.It is commonly known as the Dog fish. Scoliodon was first discovered and described by Muller and Henle (1837). The genus Scoliodon is characterized by having long snout. The teeth are similar in both jaws. Thecaudal pit andsubcaudal lobes are prominent. Scoliodon belongs to:
Kingdom Animalia
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9.1 Lateral view of Scoliodon b)Trunk – *Trunk is the largest part of the body which extends from behind the gill slits to the median ventral cloacal aperture. *It has maximum thickness in the middle region and it gradually tapers posteriorly into a long tail. *It is arched dorsally and flattened ventrally and is provided with fins(median unpaired fins, and lateral pairedfins). c)Tail–*It is the posterior part of the body behind the cloacal aperture. *It is slightly upward towards the end. *The tail contains caudal fin which is formed of a reduced …show more content…
Epidermis – *Epidermis is made up of epithelial cells. *Epithelial cells are ciliated in young stage but in adult they are non ciliated. *In between epithelial cells unicellular mucous glands are present. *The cells of outer layer are dead and form a thin squamous layer. *Stratum germinativum (Malpighian layer) is the innermost layer of the epidermis. *It regularly divides to form new cells. Dermis –*Dermis is firmly attached with the body musculature and is composed of three layers– a) Stratum laxum – It is the outer layer containing few loose fibres stratum