"Surprisingly Dead, Surprisingly Mobile"
Nothing more inviting than blue sea, blue sky and white sand. Strolling the beach, we relax and dream of a better life. We wiggle our toes in the limestone particles. We soak up the sun.
The beach is a graveyard of dead creatures and the toes have been stroking the corpses of countless lost souls. The whole beach is a disaster zone!
In a manner of speaking this is all very true. The coral sand of most tropical holiday beaches is made up of pieces of dead animals, corals, snails, bryozoa, clams and even bones. By for the greatest proportion of many beaches is the skeletal remains of single celled relatives of Amoeba, the huge group called Foraminifera. Each cellular body has a test or external skeleton of calcium carbonate. Many Pacific beaches hold huge numbers of discoid Foraminifera and many a pretty girl has had made for her a necklace of these white discs, which conveniently come with a hole in the middle.
Starsand - Foraminiferan Tests
Swimming in the shallows, these skeletal discs are all over the place - over the algae, the rocks, the less exposed coral clumps. They are as dead as those on the beach……or are they?
Collect some, put them into a glass tank, pass a good current of clean, cool sea water through the tank and "leave to simmer" for 24 hours. Next day, take a look. The discs will all have climbed out of the tank or be well on their way. Under moderate magnification, each disc will be surrounded by criss-crossing filamentous streams of cytoplasm, furiously conveying live cellular material into the digestive centre of the cell within the disc. This is a feeding factory and it's a very mobile one at that.
Foraminiferan streaming cytoplasm through pores
to catch prey - Marginapora
This article was written by Peter Parks
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