Hydra Fusca

The Hydra fusca is a small, simple, aquatic invertebrate named after nine-headed sea snake of Greek mythology due to their anatomy. It has a series of tentacles and a radially symmetrical body plan. Most hydra fusca are tiny, reaching a maximum of only about 30 mm long when fully extended. They also appear to be green due to the green algae that live inside its tissues. They can be found in most unpolluted fresh-water ponds, lakes, streams, and slow-moving rivers, where they usually attach themselves to submerged plants or rocks in the temperate and tropical regions.

Hydra fusca are carnivorous and will eat anything they can manage to catch, including small aquatic invertebrates like the Daphnia & Cyclops. To kill their prey, hydra fusca shoot nematocysts (special cells located on tentacles) in to the prey which paralyzes and kills it. It is then digested by the hydra fusca. Digestion takes place in the gastrovascular cavity over several hours in which large molecules are taken up by the gastrovascular cells, where digestion is completed. Cuticles and other undigested remains are then expelled through the mouth.

Hydra fusca live attached to vegetation by the base of the tubular body or column, with their tentacles suspended free in the water. Hydra fusca move their bodies around in the water while they are attached, extending and contracting by a combination of muscle movement and hydraulic pressure. Hydra fusca can, however, move from one spot to another, either by gliding along on the basal disc (bottom of body) or by “somersaulting “along. When somersaulting, they detach the basal disc and then bend over and place the tentacles down on an item. This is followed by reattaching the basal disc further along, before repeating the whole process again. They may also float about in the water upside down due to a gas bubble produced.

When food is plentiful, hydra fusca reproduce asexually by producing buds in the body wall, which grow to be miniature...