Click on the body part for a description
Most sharks have immovable eyelids, although some, like the Carcharinid sharks, have what is called a nictitating membrane or 'third eyelid'. This closes during feeding to protect the eye from damage caused by struggling prey. Sharks eyes have a series of reflecting plates called Tapetum Lucidum, situated behind the retina, which allows certain colours of light to be reflected back into the eye, increasing it's sensitivity in low light conditions.
A sharks sense of smell in controlled by two Olfactory sacs located in the snout. Water is channeled into these sacs and create electrical signals that the brain then translates. Sharks are said to be able to smell one part of blood per ten billion parts of water.
The spiracle is an auxiliary respiratory opening, located just behind the eyes. It allows water to be taken in, if a shark is resting on the bottom, or if it is feeding, enabling the shark to breathe and the blood to be aerated.
A sharks mouth has an array of teeth adapted to it's prey, sharp dagger-like teeth to kill and rip open large prey (e.g. Carcharinid sharks), small crushing teeth (e.g. Horn sharks) to break up the hard shells of crustaceans, to specialized 'gill rakers' for filtering plankton (e.g. Whale sharks). The mouth is also used to allow water to flow over the gills enabling the shark to breathe.
Sharks have between five and seven gill slits on each side of their body, usually just in front of the pectoral fin. Water is taken in via the mouth and pumped across the gills. Oxygen depleted blood flows through capillaries in the gills, in the opposite direction to the water, allowing oxygen to be diffused back into the blood.
A large pair of fins located below or behind the gills, used primarily for lift and fine movement control.
The anal fin is a single fin located at the rear of the shark, used to control movement, while the pelvic fins are paired and in males, have modified inner edges called claspers, used for the transferal of sperm to the female in mating. In between the pelvic fins is the cloaca, a small opening used for reproduction and excretion.
Large single fins located on the top of a sharks body, used for movement and to prevent pitching and rolling.
Present in many sharks, the caudal keel is a flattened extension of the rear body which helps to reduce drag and maintain fast movement and stability.
CAUDAL FIN / UPPER & LOWER LOBES
The caudal or tail fin is used to propel the shark through the water. Many sharks have asymmetric tails, with the upper lobe being longer than the lower lobe. This is most noticeable in the Thresher sharks, where the upper lobe can be as long as the rest of the body.