‘The Arrow Crab’
Stenorhynchus seticornis or ‘Arrow Crab’ guarding a cave entrance
Music, Video, and Aquarium
2010 Coral Morphologic

Take a moment to look into the compound eyes of the arrow crab (Stenorhynchus seticornis). If NASA is looking for a robot capable of navigating rocky planetary terrain, the arrow crab would be a perfect organism to model it after. In the video we look down the sharp, pointed rostrum (‘nose’) of an arrow crab as it appears bobbing in space. In reality, its spindly, spider-like legs are holding it anchored like a sentinel, guarding the opening of a small cave.

Arrow crabs are an abundant species on Floridian reefs, living perched near cracks and crevices in coral heads where they can retreat if threatened. Their pointed rostrum, triangular body, and protruding eyes gives this crab the appearance of a predatory lizard fish that can dash away at a moment’s notice. Instead, the arrow crab is rather slow moving, relying on the fact that the paucity of meat inside the spiny, twig-like exoskeleton of the arrow crab makes it unappetizing to a would-be-predator. This unique anatomical configuration likely explains their abundance in the wild.

Like other decapod crustaceans, the arrow crab has 10 legs (8 walking legs, and 2 pincers or ‘chelipeds’ properly). However, if you look carefully, you’ll notice that this particular crab is missing the last leg on the right side of its body. Fortunately, crustaceans are capable of regrowing amputated legs. Only a few hours after it was filmed, this arrow crab molted, and as if by magic, regenerated its tenth limb.

Tags: Aquarium, Arrow Crab, Coral, Coral Morphologic, Morphologic Studios

This entry was posted on Monday, March 8th, 2010 at 4:13 am and is filed under Natural History. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.