When we speak of Gasterosteiformes in Hawaii, we are generally referring to the order of pipefishes and seahorses. Offshore, that usually refers solely to the pelagic seahorse, Hippocampus fisheri. We see seahorses infrequently in the late summer and fall, usually at a rate of one seahorse for every ten dives or so. Imagine Bryce and my surprise, one night, when we came across a member of this family that we didn’t even realize was possible in Hawaii.
Meet the Hawaiian seamoth (Eurypegasus papilio). Sea moths are related to seahorses, pipefish, sea dragons, and sticklebacks in that they all possess bony external plates. Seamoths shed their plates, and in some cases they will go through a set of plates every 5 days. As an adult, this strange little fish will settle in water between 80 and 115 meters deep from the Big Island to Kure. The underslung mouth implies that the Hawaiian sea moth feeds on benthic animals, and the snout is probably used to help extricate small crustaceans from their holes in the sea floor. For now, the young is limited to the epipelagic zone, attracted to our lights just like, well, a moth.