Sexy Shrimp on Soft Coral

Thor amboinensis on Soft Coral

Thor amboinensis are called Sexy Shrimp because they nearly always hold their wiggling rear ends as high as possible. Reportedly this is not to attract mates, or to make dance videos, but to blend in with the motion of the coral or anemone where they live, and to communicate with other shrimp nearby. This fellow is probably male, because the stripe across his back is a single line. (In females it is broken, or two separate spots.) I think his home is a soft coral, in the family of the "true" soft corals, Nephtheidae. The octocorals, Octocorallia, are also soft corals, but have 8 tentacles on each polyp, arranged with radial symmetry.