NATURE NOTES FROM ACADIA

NOTES ON FRESH-WATER SPONGES IN ACADlA NATIONAL PARK

While visiting and camping in Acadia National Park, the latter part of August, 1934, I took advantage of a shrt respite before dinner one evening to wander about the soft margin of the small shallow Beaver Dam Pond alongside the camping area. Many small growing colonies of fresh-water sponges, dirty cream to green in color, were found on the underside of old timber and logs, and encircling roots and twigs submerged in the water. I collected only five of the best ones, those with gemmules, since the gemmules or reproductive buds are necessary for the identificatinn of species.

The fresh-water sponges are usually small, thin incrustations on submerged rocks, wood, vegatation, etc., varying considerably in shape and external appearance. Their surface is invariably dotted with fine pores. The odor of the sponge is peculiar, much like that of garlic. Internally there is a framework of fascicled microscopic spicules of silica, needles of glass, with smooth or spined surface. These are termed skeleton spicules. In some species smaller spicules are present loosely scattered in the flesh of the sponge; these are called flesh spicules. The fresh-water sponges reproduce sexually and also asexually. By the latter method internal buds or gemmules are proliferated internally, arising first as a tiny spherical body which later gradually becomes covered with one or several layers of an additional kind of spicule also of silica. The spicules of the gemmules are so peculiar and constant that they must be considered in the proper identification of species.

Four of the sponge I collected, I identified as Trochospongilla pennsylvanica. The skeleton spicules are covered abundantly with coarse spicules; and the gemmule spicules are best described as unequal birotulates, reminding one strongly of a collar button. Flesh spicules are absent. The other sponge proved to be Heteromeyenia argyrosperma. This species is characterized by having sparsely spined skeleton spicules; no flesh spicules; and gemmule spicules of two classes. One class is robust with long shafts that possess long recurved spines; the shorter class is more abundantly spined, but not as long or robust.

Spicules of the sponge Trochospongilla pennsylvanica (Potts), highly magnified. (125 of the larger spicules placed end to end would measure 1 inch). These minute objects are imbe1ded in the soft tissue and serve to strengthen the body of the sponge.

Spicules of the sponge Heteromeyenia argyrosperma Potts, highly magnified. (75 of the larger spicules placed end to end would measure about one inch).

It is of interest to report the findings of these two species because it represents the first collection from Maine. They have, however, been reported from adjoining states. These two species of fresh-water sponges together with three others - Spongilla lacustris, S. fragilis, and Heteromeyenia ryderi - reported by previous investigators make a total of five for Maine. The United States as a whole contains about twenty-eight species. An intensive survey of the fresh-waters of Maine, undoubtedly, would reveal many more species present.

Marcus C. Old
Ursinus College
Collegeville, Pa.