A QUEER DEATH-TRAP IN AUSTRALIAN SEAS

Evening Post, Volume CXXIV, Issue 69, 18 September 1937, Page 27

A QUEER DEATH-TRAP IN AUSTRALIAN SEAS

To the giant elani—it is technically termed Tridacna deresa—goes the distinction of being the largest bivalve mollusc known, says a writer in the "Adelaide Chronicle." In the coral seas of Australia's far north these amazing molluscs, which are really like gigantic cockle shells, attain a length of anything up to Bft, although from time to time northern pearl divers have reported seeing monsters up to 14ft long in- the deep waters.

The clam is a huge hinged shell, in two parts like the oyster, and an idea of its size may be gained from the fact that .half a medium-sized dam (sft long) is easily large enough to make a bath for a baby.

The weight of the shells, which are several inches thick near, the base, is astonishing; it takes two men all their time to lilt a moderately-sized clam's shell, which would weigh about a quarter of a ton, or perhaps more.

The shells are very attractive, and make striking ornaments in the home, while in many Australian and overseas churches they are used as holywater basins. As much., as £5 has been \paid by tourists visiting the Far North for a pair of large' shells.

Thousands of big ciams are to be seen along the northern coral reefs; the molluscs do not fasten themselves to th* coral or rocks, but sit, ponderous and immovable, hinge side underneath, in the coral pools. The two valves of the shell are united by a strong, muscle-like hinge, and the contractions of this hinge are immensely powerful. Practically all day and night the clam feeds with its shells wide open. In such a position the huge, flabby, whitish animal itself is completely ••' exposed. Despite ■ its great size, it lives on the tiniest organisms in the water. It is continually sucking in water, which, after every-

thing of food value has been extracted, is ejected; and often this water is ejected v with such treat force that it shoots above the surface several feet into the air like a miniature waterspout.

At the least sign of danger the clam closes its shells with a swirl, and, because of this habit, the interesting mollusc has been held responsible for numerous deaths of divers—natives and others. They have, it is said, placed a foot in a closing clam, and, with the limb held as in a vice, they have been trapped until the rising tide put an end to their struggles.

It is impossible to prise open the shells of a big clam, but it is a simple matter to open the mollusc with a crowbar or a large knife. All that is necessary is to'paralyse the' great nerve centre whicli controls the shell muscle, and the shell will gape.

But greater dangers man these surface clams are Uie real monster clams of the deeper waters. Some of the northern pearl divers can tell hair-raising stories of narrowly missing being trapped in clams measuring up to 14ft long. Caught in such monsters a man would have very little chance of escape. .' ...

But, despite the fact that they are dangerous, these giant clams are of some value. As already stated, their shells are useful as ornaments in the home and in churches, while ' many of the far northern natives use the shells as receptacles for storing food and water.

Then there is clam meat. This meat has never been utilised as a food to any great extent by white people in this country, and this is somewhat surprising, because the meat does make a palatable and nourishing stew. In the United States of America, and also in Europe, canned clam meat is extensively used.