How a squishy clam conquers a rock | Science News

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How a squishy clam conquers a rock

It turns out that this mollusk’s boring organ is anything but

By
7:00am, June 22, 2018
a giant clam

JUST THE FRILLS  Showy blue and green frills are the only visible parts of a kind of giant clam that traps itself for life inside the rocky mass of a reef by a process that’s been misunderstood for decades.

Burrowing giant clams have perfected the ship-in-a-bottle trick, and the one big thing that scientists convinced themselves couldn’t explain it, actually can.

Tridacna crocea, the smallest of the 10 or so giant clam species, grows a shell that eventually reaches the size of a large fist. Starting as youngsters, the burrowers bore into the stony mass of an Indo-Pacific coral reef, trapping themselves behind a too-skinny exit for their entire decades-long lives.

Only the extravagantly colored upper edges of the clam’s body can push out the thin slit in the reef. These protruding frills teem with algae related to those in corals. Basking in sunlight, the algae pay rent in the form of a substantial portion of a giant clam’s nourishment.

The clams “actually have eyes in this tissue,” says environmental physiologist Richard Hill of Michigan State University in East Lansing. At the slightest shadow — a predator, perhaps —

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