Sharks are generally large, cold blooded, cartilaginous fishes, which
are fast swimming, known for their numerous sharp teeth, distinctive dorsal
fin and skill in locating underwater prey. They are members of elasmobranchs
that live the same way they did more than 200 million years ago. Sharks
belong to the class Chondrichthys and the subclass Elasmobranchii. The
estimated 375 species are divided into 8 Orders emd 30 families. They range
in size from the dwarf dog-fish (Family: Squalidae], (less than 20 cm in length)
to the massive whale shark (Family: Rhiniodontidae), which reaches a length
of more than 12m. Most sharks inhabit tropical or temperate marine waters,
but some species have been found in freshwater lakes and polar seas. Depending
on the species, sharks inhabit either shallow or coastal waters or
the open ocean and some species, such as slxgill shark (Hexanchus grisens)
live at depths of more than 1800 m. Pelagic sharks Eire characterised by the
absence of spiracles when compared to the bottom-dwelling sharks, which
may posess them to breath easier while in the benthic realms.
Sharks are generally large, cold blooded, cartilaginous fishes, which
are fast swimming, known for their numerous sharp teeth, distinctive dorsal
fin and skill in locating underwater prey. They are members of elasmobranchs
that live the same way they did more than 200 million years ago. Sharks
belong to the class Chondrichthys and the subclass Elasmobranchii. The
estimated 375 species are divided into 8 Orders emd 30 families. They range
in size from the dwarf dog-fish (Family: Squalidae], (less than 20 cm in length)
to the massive whale shark (Family: Rhiniodontidae), which reaches a length
of more than 12m. Most sharks inhabit tropical or temperate marine waters,
but some species have been found in freshwater lakes and polar seas. Depending
on the species, sharks inhabit either shallow or coastal waters or
the open ocean and some species, such as slxgill shark (Hexanchus grisens)
live at depths of more than 1800 m. Pelagic sharks Eire characterised by the
absence of spiracles when compared to the bottom-dwelling sharks, which
may posess them to breath easier while in the benthic realms
