Put yourself in my place: You’re collecting mantis shrimp by cracking reef rubble on the beach of an island on the Great Barrier Reef (I know, there are worse ways to spend your day). You split one particular rock, and instead of shrimp, out pours a brood of arachnids. Not pycnogonids, not spider crabs… freaking spiders! Well, at this point, if you’re me, you shriek like a little girl and frantically crab-walk backwards while brushing yourself off.
In that embarrassing moment I had learned something new: There are arachnids that live, partially, in the ocean. These small Desid spiders live in intertidal rubble. During the day they hide in silk-sealed air chambers within the rubble. At low tide they come out to hunt stranded critters along the tide pools.
A marine spider, Desis martensi, on an out-of-water coral head. It has captured what looks like a pistol shrimp. Photo: Wild Singapore
Arthropoda 