|
|
Moss Animals
Nature Bulletin No. 138 January 17, 1948
Forest Preserve District of Cook County
William N. Erickson, President
Roberts Mann, Supt. of Conservation
MOSS ANIMALS
Last summer, several visitors in the forest preserves were puzzled by
finding masses of jelly-like substance stuck to sunken sticks in certain
ponds and lakes.
These masses were usually round or egg-shaped, ranging in size from
that of a tennis ball to that of a football. On the outside they were
covered by a grayish scum with faint lines in a coarse design. Inside
there was apparently nothing but a clear colorless jelly that quivered
and shook like a well-chilled gelatin dessert. One man guessed that it
was some sort of garbage; another, reasonably, that it was some strange
plant growth.
As a matter of fact, each mass was a colony of thousands of tiny
animals. These animals do not have true heads but each has a mouth,
surrounded by a ring of microscopic tentacles, on the end of a long
slender neck. On each tentacle are hundreds of still smaller hair-like
projections which sweep minute water plants and animals through the
mouth into the U-shaped alimentary canal. At the slightest jar they snap
their mouths and necks back into shallow tunnels in the jelly mass. This
protects them against nibbling enemies such as small fish, water neas
and swimming insects.
They are Bryozoa, which means " Moss Animals" in English. In the
freshwaters of this region there are several other kinds of moss animals
which form colonies in thick crusts, or as feathery branching tubes,
stuck to boats, sticks, stones, fishermen' s nets, and the underside of lily
pads..
Moss animals, like sponges and the jellyfish tribe, are primitive animals
that have a multitude of relatives in the sea. In the Niagara limestone
rock underlying the Chicago region, we find skeletons of many
ancestors of these moss animals that lived in the sea that once covered
this part of the continent and deposited the materials which made that
rock.
Like some people, they stick their necks out when they open their
mouths.
To return to the Nature Bulletins Click Here! |
|
Update: June 2012
|
|
