One of the few nudibranchs that swims, and it swims like an eel.
A slender dendronotid to about 6 cm, cream to pale orange, marked with an irregular network of orange-brown lines and carrying several pairs of branched processes along the back, each with a cluster of gills at its base. The rhinophores emerge from tall sheathed stalks that are themselves branched. The whole animal is more three-dimensional than a dorid and reads, at rest on a hydroid, as part of the hydroid.
Named for how it moves. Disturbed, it lifts off the substrate and swims by flexing the whole body from side to side in a lateral wave — an eel’s motion rather than the mantle-flapping of the Spanish dancer or the frantic curl of a Melibe — and it can cover a couple of metres this way before settling again. Feeds on hydroids and is found on them, usually at night. Recorded from about 3 to 25 m. The swimming is worth seeing and is easily triggered by a clumsy approach, which is a poor reason to trigger it; a photograph of the animal at rest is the harder and better one.
Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.
