Moss Animals

ChiloquinNews article Sep 16th, 2013…

This week Richard and I took the canoe out down the Wood River canal out to the river and then down to the new outlet to Agency Lake where we had morning tea on a lovely little beach before heading back against the current, which is now quite swift. Once back in the calm water of the canal we were able to give up the relentless paddling and drift along. That is when I saw the ‘moss animal’. Now I didn’t know that’s what it was called until I got back home and went to work on Google, but what a fascinating creature it turns out to be.

This magnificent bryozoan lives up to it's name. It is at least 3 ft in length

This magnificent bryozoan lives up to it’s name. It is at least 3 ft in length

I have seen them before in late summer out in the canal but never as big as one that we saw this time. It looks like a huge lump of jelly, and not what you’d think of as pretty, but definitely impressive. Even more impressive is that it is actually an animal, or a colony of animals known individually as zooids. Pectinatella magnifica (the magnificent bryozoan) is a bryozoan, with fossil records dating back to the upper Cambrian period, 500 million years ago. There are several thousand marine species of bryozoans, but less than 50 that live in fresh water. The magnificent bryozoan is native to the US, east of the Mississippi and is found in calm, shady lakes.

While most bryozoan colonies form as a layer on submerged surfaces, the magnificent bryozoan colony lives on the surface of a gelatinous mass.  A new colony begins when an individual animal (zooid) hatches from a hard seed-like “statoblast” and buds to form a small number of identical individuals.  This ‘founding’ clump of zooids secretes a watery fluid that hardens to form a firm gelatinous “core” upon which the colony spreads. The mature colony features a surface layer of adjoining “rosettes” – each with 12-18 zooids – around a central jelly-like mass that is 99% water. They feed on bacteria and algae using feathery tentacles reminiscent of corals. When these tentacles are extended during feeding the colony surface takes on a fuzzy, moss-like appearance, hence the common name, moss animal. The colonies can be free floating or attached to a submerged object.

They need warm, clean water. As the water temperature drops below 60 degrees, the colonies will die. Small seedpods called statoblasts are all that remains after adult colonies decompose at the end of fall. Each seed has jagged hooks that easily attach to an unsuspecting bird that then flies the seedpod off to new waters.

Scientists are concerned that the magnificent bryozoan is becoming more common outside its native range, not because it is harmful to water or fish, but because it may signal that waters are becoming warmer, and because by consuming algae, the magnificent bryozoan cleans up the water, allowing more sunlight to reach through, which allows more aquatic plants to grow, and shifts the natural balance of that habitat. I suspect that changing habitat would not be a concern for the Wood River canal, which is quite artificial, but that warming water would definitely be a concern for the whole Klamath Basin.

Another view of this enormous colony

Another view of this enormous colony

A much smaller but still 'magnificent bryozoan'

A much smaller but still ‘magnificent bryozoan’

This one was near enough to shore to get a good closeup.

This one was near enough to shore to get a good closeup.

magnificent bryozoan 11

Magnificent bryozoan 2

magnificent bryozoan 3


One thought on “Moss Animals

  1. Pingback: “B” is for Bryozoan on Broad Creek

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