The Dolphins of Monkey Mia

Dolphins are warm blooded, breathe air and give birth to live young.
Their streamlined, hydrodynamically efficient body shape is most suited to a predatory life at sea.
The Indo-Pacific bottlenose dolphin at Monkey Mia is a member of the toothed Cetacean family.
Members of this widespread group include other species of dolphins, porpoises, killer wales and other toothed whale species.
Dolphins have pointed beaks and conical teeth which distinguish them from porpoises that have spade like teeth and no beaks.

Dolphins sleep and rest in groups.
While a dolphin`sleeps' half the brain remains conscious, opening the blowhole to breathe and slowly moving from surface to near surface with one eye open watching for signs of disturbance.

They grow to a maximum length of 2.3m, developing speckling on the belly as they mature between 7 and 12 years.
A fully-grown bottlenose dolphin weighs about 120 kg, compared to an average human male weighing 80kg.
Some dolphins live for up to 40 years and more.

The female dolphin swims towards the shore until her belly is scraping the sea floor - then lunges.
Heaving her body almost entirely out of the water, she seizes the flapping, gasping mullet.
This moment is dangerous, if she lunge too far she risks becoming stranded.
Using strong muscular contractions and a wriggling motion she returns to the water.
Some 50 metres offshore her calf is watching, perhaps memorising this skill for a time when she is strong enough to join the fray.

Some Shark Bay dolphins use marine sponges on their rostrum (beak) as a protective tool when foraging for food on the seabed.
Seagrass meadows are also feeding grounds for green turtles and dugongs that eat seagrasses.

The deeper waters around Shark Bay are home to large carnivorous fish such as tailor as well as manta rays and sharks.
Sharks are a constant threat to dolphins and dugongs, particularly young, old and sick animals.
In Shark Bay about 1/3 of dolphin calves have shark bite scars.
Twelve species of shark have been identified in Shark Bay.
The tiger shark is the primary predator of dolphins.
Dolphins travel in groups to better detect sharks, diving deep and swimming swiftly to avoid them.




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Last updated: Friday, 04.06.2010 12:14 PM