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Q & A
Mysterious Blob - Bryozoan
Question
My son, his friend and I were wading just above the biggest island at Bainbridge on the Susquehanna River. His friend says "Look a pillow!" I was downstream from them so the "pillow" took a few moments to get down to me. I felt something rub against my leg and looked down. Slowly drifting with the current just above the bottom was a semi-buoyant blob about the size of a large raccoon but shaped like a big kidney bean or a human stomach. It undulated with the current but had no ability to move itself. It was colored like everything else in the water. If it were to sit still on the bottom you would think it was a stone. Of course the first thing I said was "Get a stick!" So, with my stick, I coaxed it over to a rock that was up out of the water and tried to roll it up on the rock. It was fairly heavy out of the water and began to break apart a little since I was lifting it with the stick. My first thought was that it was a large blob of silicone due to the fact that it was like a clear gel inside. I speculated that it had been in the water a long time to have developed the stiff outer skin and mottled or speckled appearance. So, thinking that it was not anything organic I broke it open. The gel inside, once opened, was obviously not silicone and it had a foul odor. Not a rotten type of a smell but not unlike feces. It's rather hard to describe. Anyway it now had me thinking it was some sort of jellyfish even though I've never heard of a freshwater jellyfish. The inside was approximately the same density as a jellyfish, "jiggly" if you will! It also had bright green streaks running through it and sort of had a grain to it that kind of ran towards the center (I think!). All I was fairly convinced of at this point was that it was organic. I was wishing I had a camera when I decided to collect a sample. I put about a pint sized chunk in a freezer bag along with some river water and brought it home. We've observed it for a week now and see no change other than it smells a little worse and it's a little greener! It's out in the back yard under a shade tree on a table. I would have refrigerated it but had obvious concerns about even bringing it in the house. So that's where we stand with the mysterious blob!

I thought that in my 25 years of fishing the river I had seen and could identify everything but this has me perplexed to say the least. So if you could help shed any light on the subject we would greatly appreciate it.

Answer
Thank you for the creative descriptions. It's not often people describe things to me in terms of "the size of a raccoon."  You have described a bryozoan which can range in size from a tennis ball to a muskrat up to apparently even a raccoon. Seriously, this is the third bryozoan report that I have had this summer, which is probably due to the low and clear water conditions that we have seen around the state due to the drought. They've always been there but now they are more visible to people.

Bryozoans are animals related to jellyfish and other primitive invertebrates. The animal itself is actually a colony of many individual bryozoans. The green color is due to the algae that also colonize the bryozoans. In fact just the name itself gives a clue as to the relationship between these two organisms; "bryo" refers to plant and "zoan" refers to animal. Bryozoans are usually attached to the substrate, often around submerged twigs or sticks. Sometimes they break away and then may settle wherever they come to rest. Breaking the colony up can result in new budding and growth and result in new colonies forming. They eat microscopic plankton and protozoans.

This animal is so unique it is classified in its own phylum. So, what you have seen has been around all along but now you know the rest of the story. Its nice to hear that you were on the river with your kids and now they have an opportunity to add to their knowledge of the river and aquatic life. Thanks for your inquiry.

Andrew L. Shiels
Nongame and Endangered Species Unit

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