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Two Tides Blog

Cold water sea life blog. Gulf of Maine biologists share their experiences and marine musings from Cobscook Bay on the coast of Maine! Sea life photos, science, and aquarium discussion. Comment and share your stories and questions!

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How to: Collect Dwarf Brittlestars

Wow - pouring rain here in Maine today!  Nice to be inside, but I need to go dig some sandworms - guess I will be getting wet.

I want to share my collecting notes from yesterday when I found dwarf brittlestars, genus Axiognathus, in a local tidepool. It took me years of chancing upon these little echinoderms before I realized that they were not just small daisy brittlestars, genus Ophiopholus, but a new species to me. I needed to find a few dozens of these critters for a Gulf of Maine, Inc. customer, and with my experience, I knew right where to find them.

The key habitat for Dwarf Brittlestars seems to be in shell mounds. We find them hidden among cast blue mussel shells. They are a bit hard to spot at first, and they are not kidding when they call them "BRITTLE" stars. Not only are they tiny, one has to handle them with kid gloves so to say. The best way to pick them up it to not directly pick them up. We scrape them onto shell pieces so that when they end up in our buckets, they go substrate and all.

So I headed to the tidepool on a sunny morning and managed to hit the tide at just the right time. Dwarf Brittlestars prefer to be subtidal, but you can find them at the lower end of low tides in your area. I believe that like any tidal specimen as long as they can stay moist and protected during the drain off of the sea they will survive until the flood tide comes again.

Collection

 Brittle star.

Brittle star.

I use my hands like a small dredge in low wet areas to scoop up handfuls of shells and debris and then I spread this out on a flat surface like a rock or on a ledge. Then by carefully sifting through each shell I can look for their fuzzy little arms (rays) to tip me off to where they are hiding. Often you will see only one ray protruding from the shells, but with experience they become easier to spot.  I am not sure, but I think these guys feed on detritus. Whenever I get a big order of these for Gulf of Maine, Inc. I try and find a submerged mound of shells that seems well silted and muddy. The muddier the shell mound the better the habitat. Once I found a one gallon plastic milk jug that had been sitting on the sea floor for a long time. When we emptied it of muddy silt, out came a pile of dwarf brittles. It makes sense that this habitat would work well for them not only for feeding, but for protection.

 Dwarf brittle stars.

Dwarf brittle stars.

It did not take me long to get the stars I needed to fill my order and to head off to work. I saw lots of sylky sea cucumbers, limpets, scuds, trumpet worms, and other inverts as I collected but did not need any of those at this time. Will get those later - it was time to head out. Lots to do as I have been away from the office for about three weeks and it is time to catch up.  

Catch me next time in the tidepools!

Tidepool Tim