|Halichondria panicea on one of my fouling panels, surrounded|
by two spirorbids and a bryozoan. Photographed at 50x
There's only one species of sponge showing up on my fouling panels right now, and it only appears in Eel Pond. It's Halichondria panicea, and it's actually a non-native species. It was introduced to New England, presumably a long time ago, though nobody is quite sure when. It's been around long enough to become well-established in the fouling community.
When I first started seeing Halichondria on my panels, I didn't know what it was. It took me a little while to clue in that it was a new organism. Once I recognized its porous texture, though, I could identify it almost immediately!
Sponges are typically slow-growing but are good competitors, so they tend to dominate older communities. I anticipate that Halichondria will come to occupy larger and larger amounts of space on my fouling panels as the summer goes on. We'll see if I'm right!