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The shark kidney excretes urea that is needed for the shark to have in its system so the shark does not become dehydrated from living in seawater. [14] Sharks hearts have two chambers. The shark heart's main importance is providing oxygenated blood to the entire body while filtering out the deoxygenated blood. [15]
Many sharks can contract and dilate their pupils, like humans, something no teleost fish can do. Sharks have eyelids, but they do not blink because the surrounding water cleans their eyes. To protect their eyes some species have nictitating membranes. This membrane covers the eyes while hunting and when the shark is being attacked.
A great white shark at Isla Guadalupe, Mexico. The following outline is provided as an overview of and topical guide to sharks: . Sharks (superorder Selachimorpha) are a type of fish with a full cartilaginous skeleton and a highly streamlined body.
Welcome to the shark portal! Sharks are a group of elasmobranch 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 Batoidea (rays and kin).
Like all sharks, hammerheads have electroreceptory sensory pores called ampullae of Lorenzini. The pores on the shark's head lead to sensory tubes, which detect electric fields generated by other living creatures. [16] By distributing the receptors over a wider area, like a larger radio antenna, hammerheads can sweep for prey more effectively. [17]
While tiger sharks, which are typically both a few feet smaller and have a leaner, less heavy body structure than white sharks, have been confirmed to reach at least 5.5 m (18 ft) in the length, an unverified specimen was reported to have measured 7.4 m (24 ft) in length and weighed 3,110 kg (6,860 lb), more than two times heavier than the ...
Greenland sharks have also been found with remains of moose, polar bear, horse, and reindeer (in one case an entire reindeer body) in their stomachs. [26] [27] [28] The Greenland shark is known to be a scavenger and is attracted by the smell of rotting meat in the water. The sharks have frequently been observed gathering around fishing boats. [26]
Batoids are flat-bodied, and, like sharks, are cartilaginous fish, meaning they have a boneless skeleton made of a tough, elastic cartilage. Most batoids have five ventral slot-like body openings called gill slits that lead from the gills, but the Hexatrygonidae have six. [3]