Carnivorous Sponges

From: Peter F. Keller (pfk6@juno.com)
Date: Tue Feb 18 1997 - 06:50:58 PST


Date: Tue, 18 Feb 1997 09:50:58 EST
From: pfk6@juno.com (Peter F. Keller)
To: cp@opus.hpl.hp.com
Message-Id: <aabcdefg634$foo@default>
Subject: Carnivorous Sponges

While we're on the subject of carnivorous fungi, how about sponges.
The following was from an article in one of the local papers taken from
AP in 1995.

     Unlike other sponges, the newly discovered deep-sea sponge
"Abestopluma" turns nature inside out. It has evolved a taste for animals
that happen to swim into its spindly arms.
     In contrast, ordinary sponges-including the bath kind-are
filter-feeders, using small chambers to screen out tiny plants that flow
through with seawater. So the discovery is a true surprise, reported in
the British journal Nature.
     "All available evidence shows that the sponge is an effective
carnivore," wrote marine biologist Jean Vacelet, at the University of
Aix, in Marseille, France.
     Vacelet said the carnivorous sponge were found in a submerged
Mediterranean cave, where normal sponge food-tiny marine plants-is
scarce. Similar sponges, probably also carnivorous, tend to live about
30,000 feet deep in the open sea. The plants are also rare down there.
     According to zoologist Michelle Kelly-Borges at the Natural History
Museum in London, "sponges are impressively adaptable to their
environment." But it's surprising one evolved so thoroughly it doesn't
much resemble a sponge anymore.
    Instead of small chambers where tiny plants get caught, the new
sponge grows spike-like "grabbers" on its spindly arms that snare
unfortunate creatures that swim too close.
     Once it has caught dinner, cells in the sponge's filamentary arms
migrate in, cover up the captive and begin digesting it. Digestion is
complete within a few days.
     "The high frequency of crustaceans found still alive, or in various
stages of decay in the sponge's grip indicate it dines on live seafood,"
Vaeclet said.
     Although the scientists likened the sponge's surface to the
hook-rich material in Velcro, perhaps the capture technique in more akin
to the story of Br'er Rabbit and the tarbaby. Once stuck, legs and other
appendages get more and more entangled as the animal struggles to escape.



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