Did you know … Did you know … Over half of Australia’s The largest fish in the SHARK – external anatomy shark species do not sea, the whale shark, grow to more than is a cartilaginous fish There are approximately 500 shark species worldwide and more than 100 of one metre in length. and may reach up to these are found in Western Australian waters. They are distinctive in that they 12 metres in length! have a skeleton made out of cartilage – a material that is softer than true bone. This lightweight skeleton provides a flexible framework for muscles to move. Dorsal fin Similarly to bony fishes, dorsal fins in sharks act like a yacht keel to keep them stable. Sharks take in water through the mouth or spiracle – an opening just Gills behind the eyes (of some In front of the sharks pectoral sharks). They are modified fins are 5-7 gill slits which Second dorsal fin gill slits that allow fish to serve as valves to let water out. Oxygen and carbon Nostril take in oxygenated water. Spiracles help a shark to dioxide are exchanged across The mouths and the gill surface. nostrils of sharks are breathe when it is lying on the underside of on the sea bottom or even the head (ventral), buried right under the sand. rather than on the dorsal surface as in most bony fishes.

Eyes Some sharks eyes Caudal fin are protected Mouth Most sharks have a by eyelids, a Cartilaginous fish have jaws but their heterocercal tail – that third protective teeth are embedded in their gums Pectoral fin is, the top lobe is larger eyelid called (rather than attached to their jaws). Pectoral fins can be used Anal fin than the bottom lobe. the nictitating The teeth are constantly replaced individually to manoeuvre the Like the dorsal fins, the This forces the nose of membrane, with and most sharks have several rows of fish up, down and sideways. Pelvic fins anal fins play an important the shark up as it swims some also able to developing teeth behind their main Together, these fins act as The pelvic fins are role by acting as stabilisers (which is balanced by roll the eye back row, waiting to be used whenever a brakes and the fish can also use used for braking – without them the fish down force provided by into the socket. tooth is broken or dislodged. them to swim backwards. and steering. Claspers would roll over on its side. the pectoral fins). Male sharks have claspers Ampullae of Lorenzini that are used to attach to A network of jelly-filled females during mating pores used for detecting the A shark’s body form may also and insert sperm into the depict where it lives. Gigantic bioelectric fields produced female’s body. Cartilaginous by prey, potential predators filter feeding sharks, e.g. basking shark, found largely fish all reproduce by internal and conspecific during in the pelagic zone resemble fertislisation and either give social interactions whales, whilst reef sharks birth to live young (as is are well adapted for their the case with white, mako environment with their wedge- or tiger sharks), or lay a few Many sharks use camouflage in the Sharks have small tooth-like scales, shaped heads for getting into large eggs (as in the bottom cracks and crevices. Carpet-like form of countershading. Their bodies called denticles, embedded in their wobbegongs camouflage dwelling Port Jackson sharks. are blue or dark grey on the top and skin. The image above is an extreme Sponsored by: amongst their coral or algae silvery or white underneath, making close-up of great white shark skin. them less visible to predators and Department of habitats. Photo: © Trevor Sewell/Electron Microscope Primary Industries and prey above or below them. Unit, University of Cape Town Regional Development Marine Waters marinewaters.fish.wa.gov.au 2844/17