Trappers


On Shalimar, we found that some of the animal cells in the oceans are grouped together in small clusters. Some are grouped in open circles, perhaps in order to surround a morsel of food. We hypothesize that some of these rings stayed together to make short tubes, and later learned to close the ends of the tube to entrap prey. There are a number of different organisms that have this form, which we have named ring traps.

A further development is that some of the ring traps have developed chitin-like outer plates. The ring traps tend to be small, and their armor is very light. They float among the many organisms near the surface of the shallow water.

We first noticed the Grabbers when we were looking at unicellular life forms. They would appear to be related to the armored rings, but are covered by a single shell (fused from outer plates?) on the top and a similar second shell on the bottom There are many very small grabbers among the tiny organisms that float in the water. Part of the time they are hidden in their small oval translucent shells: they suddenly reach out with tentacles or claws to capture some item of food and then retreat into their shells again.

The trappers impressed the exploration team with their single-minded ferocity. Trappers seem very focused on capturing food, and are apparently successful enough to survive without being aware of predators. They are very prolific organisms, releasing many small hard-shelled capsules containing their genetic material. In some varieties, one or two of the capsules are sometimes retained, allowing the young to develop inside their parent into a small but fully featured copy of the adult. Larger trappers will eat smaller ones, thus providing a measure of population control.

We were later to find larger grabbers that had become bottom dwellers. They live among the stones on rocky patches of the beaches. Some of their grabbing arms are used as legs for moving about between the stones. Their digestive tracts are simple, U-shaped tubes that go down the length of their protective shells, turn, and come back toward the front of the shells. The larger grabbers have developed complete exoskeletons, with particular emphasis on the development of their grasping organs.





© Elizabeth Anne Viau, 1996. This material may be used freely for instructional purposes but not sold for a price beyond the cost of reproduction. Please e-mail me at eviau@earthlink.net if you use this material. I'd be interested to know how it works for you!