Info on hydroids from Dr. Ron.
http://www.rshimek.com/odd_critters.htm
The animals are between one and two millimeters in diameter. These are organisms which are turning out to be relatively common. They are crawling hydroid jellyfishes, which do not swim, but rather move around the tank sort of like a small, soft, slow spider. They move by fastening on to the substrate with their adhesive patches. The tentacles are tipped with concentrations of nematocysts. There is a red eyespot at the base of each tentacle. These organisms become quite abundant in some reef systems, and then rapidly disappear without a trace.
A Japanese researcher, Dr. Yayoi Hirano, provided the following information:
"They are crawling hydromedusae, in the species Staurocladia oahuensis. There are about 15 species of this genus known in the world. All of them have branched tentacles, and can adhere to substrata, such as algae, by the tentacles, with the surface with eyespots facing upward. The tip of the lower branches are used for adhesion, and the upper branches have a few or more (depending on species) nematocyst clusters. Arrangement of the nematocyst clusters is a key to identify species. They reproduce asexually either by budding or fission, so under favorable conditions they often can become abundant in aquariums. This species has been found in a fish farm and also in a abalone aquaculture center in Japan. It seems the species has a high rate of asexual reproduction under favorable conditions. Even one jellyfish accidentally introduced in an aquarium may increase in a population of hundreds within a few months if the conditions are really good. It is also very possible that the polyp stage of the species lives on corals or rocks which may be brought into the aquaria. The polyps may form a dense colony if it is provided with much food. Within a short time the number of polyps may be very large, and the polyps may produce many jellyfish. The jellyfish and polyps will eat Artemia nauplii and copepods.
