Jeff Green | Sep 15, 2005
Nature Reflections - September15, 2005
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Nature ReflectionsSeptember 15 2005
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Gray MerriamLegaleseGeneral information and opinion on legal topics by Rural Legal ServicesNature Reflectionsby Jean GriffinNight Skiesby Leo Enright
by Jean Griffin
There is always something new to learn from nature. Last week I had an email from Dorina about a strange object that had appeared in a pond. Only by going on the Internet had she found out what it was - a Moss Animal or Pectinatella magnifica. Never having heard of this before I also went on the Internet and learned one of nature’s lessons.
My lesson was on Moss Animals or Bryozoans. The football-sized object found by Dorina was actually a colony of these tiny animals called zooids (bear with me - I will in future call it the "blob") living cheek to jowl in a colony. This colony is gelatinous, firm and slimy to the touch, with the gelatinous mass being mostly water (about 99%), and the surface appearing to be divided into rosettes, each made up of 12 to 18 zooids. Dorina said the surface looked "like a golfball".
These not uncommon colonies or blobs will form on submerged logs, sticks, wooden docks, rocks, etc, and unless they attach to someone’s irrigation intake pipe and clog up the system they are rarely seen. A blob may be up to two feet in diameter with up to two million of the genetically-identical zooids, though more commonly football-size or smaller. Favourable water conditions and temperature encourage rapid growth in the size of a blob.
These blobs are harmless to humans, functioning as filter feeders as they remove nutrients from the water that surrounds it. Generally they are found in stagnant water high in nutrients such as ponds or canals. Each of the tiny animals has a food-gathering structure with many ciliated tentacles extending like flowers when the animal is feeding, or withdrawn into the interior. They feed on even smaller animals and plants which we don’t see when we glance into the water. A magnifying glass with a three to five power magnification will reveal the individual zooids. When disturbed these contract, but if placed in water and left undisturbed, in a few minutes they will extend themselves and become active, waiting for food, and reacting when a morsel touches the tentacles.
If threatened by fish predation (yes, they in turn are eaten by larger creatures), the blob will emit a pungent odour. At some time in the late summer or early fall the blob will break up into small, circular, disk-like cysts, each bordered by a crown of spines In this form the animals are resistant to severe environmental conditions and this is the means of survival of the animals from year to year.
Here endeth the lesson!