Grey Nurse sharks - habit and habitat
The food Chain
Grey nurse sharks eat a wide range of small fish, squid and crustaceans. They hunt cooperatively and can round up schools of fish. Their lanceolate teeth with characteristic lateral cusplets are well suited to holding and piercing slippery prey rather than cutting. Their teeth are shorter towards the back of the mouth. Grey nurse sharks are by no means at the top of the food chain. There is evidence from satellite tracking that they will move out of the area when great whites are around.
BuoyancyBony fish maintain buoyancy by means of air bladders, which sharks and rays don’t have. Their cartilaginous skeletons are less dense than bony ones and sharks have large oily livers which reduce their density. In addition grey nurse sharks can gulp air at the surface and hold it in their stomachs to increase buoyancy
Where they liveThe grey nurse sharks were once widely distributed, in the Mediterranean; Atlantic, Indian and western Pacific oceans. They are now facing extinction. They can still be found of North Carolina where they are known as sand tiger sharks and off Natal where they are called ragged-tooth sharks. In Australia they are found off the south west of WA and along the east coast from southern Queensland to southern NSW. The two Australian populations are believed to be genetically separate. Tagging has shown that they may travel over long distances but have their preferred aggregation sites.
The
grey nurse sharks can be seen at a number of sites along the NSW
and southern Queensland coasts. They are usually found in sandy
gutters and rocky caves from about 15 - 40m. At Julian Rocks they
have been sighted in all months but the best chance of seeing
them is in winter, when the water temperature is below 22c.
Grey nurse sharks will come quite close to divers, without paying much
attention to them; they seem quite aloof, just minding their own
business. Sometimes, when they seem disturbed, they will make
a snapping sound with their tails, and then rush off. Their palcid nature contributed to their demise