Sharks hunting across land and sea
Introducing the tidal pool predator
By Annette J Beveridge
Tucked away in the crevices of a reef, a small shark waits for the tide to recede exposing a network of rock pools where this shark can hunt without fear of becoming prey.
The Epaulette shark is highly adaptive using its pectoral and pelvic fins to walk and crawl while wriggling its tail to move across the ocean floor emerging to explore the series of rock pools left behind as the tide goes out.
A fish out of water?
Unlike other sharks, the Epaulette has developed the ability to manoeuvre out of water and to survive up to 60 times longer without oxygen than we can. This was discovered by scientists in the 1990s.
Epaulette sharks can choose to direct blood flow to the areas of the body that are most essential. This requires real physiological changes to slow its breathing and heart rate and the brain simply powers down.
Once on land, Epaulette sharks move into rock pools and begin the hunt for crabs, small fish and worms.
Tide pool hunting grounds
Tidal pools have depleted oxygen levels during low tide due to the lack of water washing into the pool so the sharks adaptation to low oxygen environments can make a big difference for its ability to survive. Even environmental conditions with less than 5 % oxygen will not lead to any loss of responsiveness.
Olfactory and electroreceptive senses help the shark to locate prey which may be hidden. Prey is quickly sucked in but any crustacean with a hard shell is crushed in the teeth first. Any sand that is taken in at the same time is expelled from gill slits.
One Epaulette shark is recorded to have reached 42 inches in length although the average length is 35-37 inches.
Burping
Epaulettes use a process of breathing known as buccal pumping. This is where they pull water in through the mouth and push it out through a series of bones (operculum) located near the front of the body. Water to flow over the gills and this enables oxygen to be absorbed from the water.
Epaulette sharks are found in the Western Pacific Ocean and close to New Guinea and Northern Australia. They inhabit areas up to 50 metres deep and are largely nocturnal.
Reproduction
Females initiate the courtship and show interest by biting their chosen mate. Mating occurs between July and December and the female will lay between 20-50 eggs. The young emerge from the eggs after four months and take care of themselves. Sexual maturity is reached at seven years.
Epaulettes can live between 20-25 years and weigh just 1-2kgs. The large black spot located on the body behind the pectoral fin is the reason for its name as it resembles military epaulettes.
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