Thursday, March 13, 2008

"Let's split!"

This is a very delightful article:
Male and female sand dollars typically reproduce by releasing sperm and eggs into the water where they join and become baby larvae. Sand dollar larvae had previously been observed cloning themselves to accelerate a population boom when food is abundant.

But Ms. Vaughn wanted to see what defenses the baby sand dollars had evolved to avoid being eaten.

She took four-day-old larvae and placed them individually into shot glasses — the glasses more commonly used for downing tequila — together with water, algae for food, and mucus she had swabbed off Dover sole, a fish that happily eats larvae.

Within 24 hours, many of the single larvae had become two, either by simply splitting in two or, more commonly, by growing a bud that then detached and developed into a smaller larva. The cloning process is too slow to save a baby sand dollar if a predator, mouth open, is closing in on lunch. But if the larva detects the predators when they have just entered the neighborhood, there is often enough time for it to split.

None of the larvae placed in shot glasses without fish mucus split.
Sometimes one must fall back on the Amazon formulation statistically improbable phrases....

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