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Freshwater Sponge!

Photo: Wikimedia Commons, photographer unattributed

Orange and tubelike, a common antlers sea sponge, Axinella polypoides, grows among other sponges on the  sea floor, probably somewhere in the Indian or Pacific oceans. These strange organisms are familiar to viewers of Jacques Cousteau type shows, or people who are fortunate enough to dive in such places.

 Photo: John Pogacnik

While hopelessly landlocked in my office yesterday, I was texted a photo of a bizarre growth by John Pogacnik, who was, along with some others, exploring the Grand River. Neither he, I, or anyone he was with at the time recognized this thing. A quick bit of sleuthing by Judy Semroc led to Tim Wood of Wright State University, who was able to identify the organism. It is a freshwater sponge!

Dr. Wood studies freshwater bryozoans, which are in a different phylum than sponges, but he obviously doesn't ignore other strange underwater critters and pinned this one to the correct family, and even genus. It is a sponge in the genus Spongilla, and may be the species Spongilla lacustris.

This is a totally new one on me, and indeed the find offers me my first blogging foray into the Phylum Porifera, a group made up of simple filter-feeding animals. There may be as many as 10,000 species of sponges worldwide, and the vast majority of them live in oceans. I had no idea that we had freshwater sponges in Ohio; learn something new everyday!

Photo: John Pogacnik

This sponge is one of few cases - at least in these parts - where it would be easy to confuse the animal and plant kingdoms. One could be forgiven for thinking that this sponge is actually some sort of odd aquatic plant, when in reality it is a simple rather formless animal.

Sponges are all about water intake efficiency, and the need to constantly draw in H2O accounts for their long tubular growth habit. The innards are comprised of long channels, and external water is drawn in through openings called ostia. Lashlike flagella beat near the ostia, and draw in the water from which minute organisms, algae, bacteria and who knows what else are extracted and digested. Because of the need for clear water to feed in, sponges apparently fare poorly in waters that are excessively silted or otherwise polluted.

John and company found these sponges at Lake County Metropark's River Road property, an area known for its outstanding aquatic health. Not too far away is Ohio's only known site for riverweed, Podostemum ceratophyllum, an aquatic plant that only grows in high-quality streams. I'm sure it is no coincidence that these sponges are in the Grand River; another interesting piece of evidence that testifies to the topnotch ecological health of this State Scenic and Wild River.

Kudos to Lake County Metroparks, the Cleveland Museum of Natural History, Ohio Department of Natural Resources, Western Reserve Land Conservancy, Ohio Chapter of The Nature Conservancy, and everyone else who works to keep the Grand pristine. I wrote a piece about one of TNC's Grand River projects RIGHT HERE. Maybe few people would care about freshwater sponges, but I think they are quite cool indeed, and am glad that we still have streams that will support such life.

P.S.: If you know anything about the presence of these sponges in Ohio, please let me know.


Tom Arbour said…
Although I don't know much about them, I found something similar when I was taking a freshwater invertebrate class- it was growing in the clear waters of a beaver pond near Hiram. In Maine, my in-laws pond s full of something quite similar.
Dave said…
I used to find them with some regularity in the Sandy Creek at Malvern. They were also common in a number of other streams in Carroll County. They would cover a good bit of the bottom of the riffle below the Rt. 183 bridge. Not an especially clean river, but it was just downstream from a gravel pit that may have had the effect of filtering out a lot of silt. Interestingly, there is a chironomid larva, Xenochironomus xenolabis, which lives in and feeds on the sponge, and these were common in Malvern as well.
Kenn Kaufman said…
This is fascinating!! I have to admit, I had no idea there were freshwater sponges anywhere, let alone here in Ohio. One take-home message is that the Grand River is even more important for biodiversity than we might have realized before, and even more richly deserving of protection. Thanks for sharing this phenomenal news!
Ken Wood said…
Thanks, Jim (and Judy, John, Tim and many others) for spreading the word about the wonders of the Grand River watershed. Here at Western Reserve Land Conservancy, we're proud to be one of the many organizations working to preserve this amazing region. Thanks!
rebecca said…
Cool! I remember someone showing me a freshwater sponge during a field lab back in college (in Ohio) but I don't remember where.
Jim McCormac said…
Thanks for your comments everyone, and the other sponge reports. And Ken, thanks go to you and your organization's hard work in conserving the Grand. I'm taking a long overdue trip up there Sunday with Pogacnik. We'll see sponges, rare plants, scads of cool dragonflies and much more. Expect additional blogs from the Grand!
Anonymous said…
I've never seen a freshwater sponge in person, but learned about them from Dr. Wood himself. I had the pleasure of learning from Dr. Wood about lots of other aquatic creatures too. I'll never forget the day he had us out sampling stuff in Huffman Lake (created during construction of Huffman Dam on the Mad River). I found a small bryozoan growing on a submerged stick, and asked him to ID it. He told me what it was, then added, " I described that species, and this is the type locality." He would've been the first person I emailed with this photo too.

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