Moss animal is the common name for Bryozoa. Most of the known 3,500 species of moss animals are marine species but there are also about 50 freshwater species. Some of those will sometimes appear in the home aquarium.
Moss animals live in large colonies and resemble a mass of very small marine feather dusters. Individuals in the colony are called zooids. The have small hair like tentacles that retract when they are disturbed. The tentacles bring food to the animals. They eat algae and protozoa.
Moss animals may show up in the aquarium occasionally, unfortunately I've never been able to keep the colonies alive more than a few months at a time. They will sometimes show up on a somewhat regular basis in the same tanks. The moss animals I see most often in my aquariums form branching colonies, though other speices form different types of colonies. Some very large colonies that look like a gaint egg mass are found in some lakes.
The photo shows moss animals in one of my aquariums. The zooids pictured have produced statoblasts. This is an asexual form of reproduction. Statoblasts, are somewhat similar to seeds in plants. They are resistant to adverse conditions and can germinate to form a new colony when conditions improve.
| Moss Animals
| Leeches, Worms, and Planaria
| Small Crustaceans
| True Bugs
| Ramshorn Snails
| Pond Snails
| Malayan Livebearing Snails