Animals Territory | Shark | Sharks are a group of fish
characterized by a cartilaginous skeleton, five to seven gill slits on
the sides of the head, and pectoral fins that are not fused to the head.
Modern sharks are classified within the clade Selachimorpha (or
Selachii), and are the sister group to the rays. However, the term
"shark" has also been used for extinct members of the subclass
Elasmobranchii outside the Selachimorpha, such as Cladoselache and
Xenacanthus.
Shark
Shark pictures
