The family hydrozoa has a genus, Hydra, which have been known for many years to be useful in laboratory experiments. Hydra are small fresh water coelenterates which are essentially carnivorous and which reproduce both asexually and sexually, depending on the temperature and other environmental factors of the fluid medium in which they are contained. They comprise a body, having a foot or member adapted for attachment of the creature to a surface at one end of living the body, and a plurality (on the average 6.3) of food gathering tentacles at the other end. They eat by grasping a small portion of living food matter from the fluid medium with the tentacles and pushing it towards their mouth which is more or less at the juncture of the tentacles.
The use of hydra in various sorts of laboratory experiments has been a common practice for many years. However, there has not been developed a labor-efficient method for their uniform production. Rather, hydra have been grown in individual laboratory dishes or bowls. Inasmuch as hydra must be almost daily cleansed and fed, the use of such dishes for their containment has led to certain problems. In particular, laboratory technical personnel have been required to spend considerable time in removing the individual hydra from the dishes, cleansing them in water and returning them to clean dishes. In a typical laboratory experiment, as many as 12 large finger-bowl type dishes of hydra may be required and several hours of time is required to take care of these. Moreover, such dishes are not particularly well adapted for the rapid reproduction and growth of hydra since they are not readily temperature controllable and require large volumes of fresh culture medium 4 or 5 times per week, since the medium tends to become stagnant if at rest in such dishes. Therefore, there has been a need in the art for more efficient hydra cultivation methods and apparatus. Moreover, since the hydra must be removed from the dishes for cleaning, which prevents a stable population from being formed, and causes adult hydra to be killed during transfer to clean bowls, a need exists for a method and apparatus for cleaning the hydra without removal from their environment.