A strange, jelly-like blob has been observed around the dock or among fallen tree limbs in shallow areas. Before you start stringing yellow caution tape around your pond and calling the Environmental Protection Agency, let’s examine this object that resembles something from outer space. These critters are called bryozoans or “moss animals”.
Some freshwater varieties are considered useful indicators of water quality. Scientists say they like water that is eutrophic or has lots of food. Freshwater bryozoans live in colonies and can get as big as basketballs. Since they’re “aquatic animals”, they digest microscopic creatures like plankton by filtering water. They’ve been around 500,000,000 years.
Bryozoans contribute positive and negative effects. Positively, they may circulate nutrients and deliver food to other organisms. Negatively, they can grow on pipes, thereby, disrupting drainage and irrigation systems.
At the end of the summer, as lake temperatures cool, bryozoans die. The jelly dissolves releasing small, dark brown disks. The disks remain dormant for some time, withstand drying and freezing, and survive the winter to start new colonies next year. While appearing ominous, the blobs typically pose no threat to lake users.