#phyllodocida

The everted proboscis and jaws of a nereid worm (Nereididae sp.) in French Polynesia - Pōrīnetia farāni

Eunicida. This order of benthic marine worms includes the Bobbit Worm aka the sand-striker

Phyllodocida. This order of marine worms are mostly benthic, but some, like the Gossamer worm, live in the open ocean

This is Aphrodita aculeata, also known as the sea mouse! It is a species of bristle worm that possesses brilliantly bright hair-like structures known as setae. Unlike mammalian hairs (which are made of keratin), setae are composed of chitin. These setae are actually hollow tubes composed of hexagonal cylinders; the structure of the setae allows for their spines to reflect visible light with a reflectivity of 100% to the human eye. This is why it appears so vividly kaleidoscopic. The scales covering its back are its elytra which are not actually morphologically equivalent or even related to the elytra possessed by beetles.

They typically grow between 10-20 centimetres long, and their main diet consists of other annelid worms and crabs. They were noted by researchers to devour prey up to three times its size head first: Gunnar Thorson was quoted as saying that it was similar "to a hedgehog swallowing a snake". They were also noted to only feed when their head was underneath the sand (its preferred state of being), and it would only eat at night.

Unlike many other bristle worms, the sea mouse moves itself forward in a "fast stepping pattern" instead of a more undulating motion.

Its setae have a potential use in the manufacturing of nanowires due to the same properties that produces their iridescence.

Sea mouse (Aphrodita aculeata)