Well the great Pond Scum tour, did not disappoint. I hosted Ted Harris a researcher at KU’s Biological Survey and Will Boyer, a KSU Watershed Specialist. Even though there was a breeze and the ponds looked considerably better than before. We were fortunate to find some Bryozoa in one of the ponds. At first glance, we thought they were white rocks. We were able to fish one out and discovered it was a Bryozoa or moss animal. It is an aquatic invertebrate animal. They are simple animals rarely growing more than 1/25th of an inch in length. However, most bryozoans form colonies that can vary greatly in number, form and size.
Each individual animal, or zooid, has a simple body style, usually round or oval in shape with a single opening that serves as both a mouth and an anus. Bryozoans lack any respiratory, excretory or circulatory systems, but have a central nerve ganglion that allows the animal to respond to stimuli. They feed using small tiny ciliated (hair-like) tentacles that the surround the opening and push food through it into the gut. In some species, and during certain life periods, these tentacles can be used for simple movement. Most species, however, spend the majority or all of their lifespan immobile.
The vast majority of Bryozoan species are marine animals. Of nearly 5,000 species, less than 90 have been identified in freshwater environments, and only 24 freshwater species in North America (so far).
We found the Magnificent Bryozoan (Pectinatella magnifica). This colonial species forms jelly-like “green blobs” on underwater vegetation, branches and other structures. They may also form free floating round colonies. The small visible rosettes on the surface of the colony are groups of 12-18 individual animals.
Although the Magnificent Bryozoan reproduces both sexually and asexually, the main way the colonies form is when the existing individual animal or zooid breaks away or buds asexually forming a twin. As they reproduce, they multiply into an ever growing sphere as the individuals point their mouths outwards to take advantage of available food. Meanwhile, the zooids excrete gelatinous material to give the sphere interior support.
Completely new colonies can also form asexually from small statoblasts (a group of cells encased in a hard covering to protect them from freezing or other harsh conditions). These statoblasts can float in the current, or settle to the bottom where they eventually grow into an individual zooid. These individual zooids can use their ciliated tentacles to move about in the water. They will eventually begin dividing and form a new colony.
The Magnificent Bryozoan actively feeds on suspended organic material, zooplankton and algae. In this way it can be considered a filter feeder and may, in some instances, increase water clarity. Individual animals on the colony are clear or opaque. It is speculated that the green color of the colonies stems from ingested algae. This was a sign of a very healthy pond!