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Posts Tagged ‘bryozoans’

Thingy Thursday: The Blob

Thursday, December 16th, 2010

You know how images and thoughts evoke emotions or sensations? Well, considering La Nina’s recent fury and the approaching dark of the winter solstice, I figured I’d share a creature that takes me back to the heat and sun of August.

Football-sized Pectinatella magnifica bryozoan colony. Photo: Jeff Adams

One of the more common summertime unknowns (often presented with concern or disgust!) is a freshwater colonial invertebrate called Pectinatella magnifica, the magnificent bryozoan. Magnificent is part of its scientific name, but dragon boogers seemed more appropriate to my 5 year old.

These gelatinous blobs feel kind of like a jellyfish, can grow larger than a basketball and are made up of thousands of tiny individuals living on the surface. At their healthiest, they tend to be a beautiful purple color with hundreds of white-speckled groups of living individual called zooids. These clusters look like snowflakes or rosettes.

Like a jellyfish, much of the blob’s mass is water. In this case, that mass is a non-living part of the colony in which the living zooids are embedded and contribute to its formation. The tiny individual zooids are ecologically similar to corals or hydra, in that in that they have delicate tentacles that they expose to the water and use to capture fine, drifting organic material (the hydra are after tiny animals). They can also pull those tentacles into the protective, non-living body of the colony when disturbed.

Close up of Pectinatella colony and clusters of individuals. Photo: Jeff Adams

These large gelatinous blobs form in warm (>16°C or 60°F) slow or still water (the images to the right and below are from the Columbia Slough in Portland, OR).  Smaller blobs may be free floating, but larger ones usually grow on branches and vegetation. Those growing on plants may also float when plants begin to die off and drift in the late summer and fall. Sometimes, the blobs become so numerous they clog water intakes and requiring 24 hour attention.

By the time vegetation starts breaking down, the colony is probably dying off as well.  However, they leave behind an unusual reproductive structure that can withstand cold, heat, drying, and time. These seed-like statoblasts are a collection of cells inside a protective shell, and they carry on the lineage of the parent colony. The statoblast is formed out of a connection to the parent zooid’s gut and can either cling to the colony or drop to the sediments or be transported to new locations by other wildlife. Each little survival pod can start a new colony whenever and wherever conditions are favorable.

Microscope photo of Pectinatella statoblasts. Each is only slightly larger than the thickness of a dime, but can produce an entire colony. Photo: Jeff Adams

Statoblasts are a specialized characteristic of freshwater bryozoan species. Marine waters are where bryozoans are truly diverse with thousands of ocean dwelling species, while there are only a couple dozen species known in freshwaters of North America. The magnificent bryozoan is certainly the most… magnificent among them.

The magnificent brozoan is classified by the USGS Non-indigenious Aquatic Animal database as a native transplant – native to the warmer water east of the Mississippi and transplanted out west. Though it may have just been widespread and no one gave it much attention. Maybe climate change will allow it to be happier in our usually colder waters?

Now when you take a break from your winter labors, close your eyes and imagine yourself floating on the surface of a warm lake or down a slow river… Please forgive me for the slimey blobs that start bumping up against your imagination, leaving you speckled with statoblasts, and cursing me for having wrecked your perfectly good escape. Happy daydreaming!

Jeff Adams is a Washington Sea Grant Marine Water Quality Specialist, affiliated with the University of Washington’s College of the Environment, and based in Bremerton. You can follow his Sea Life blog, email to jaws@uw.edu or call at 360-337-4619.


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