Aplysia elongata was common on intertidal and shallow subtidal reefs around Oahu, such as Diamond Head and Kewalo. It varied in color from spotted nearly all black, as seen in the photos below. The black specimen was found in the shallows near the tables at the Three Tables dive site on Oahu's north shore. Formerly considered Aplysia parvula, it was shown by molecular data (Golestani et al (2019)) to be distinct and is considered endemic to Hawaii.
The black form very closely matches a black form of what is considered to be Aplysia nigrocincta in the Marshall Islands.
In the bottom photo, three specimens are riding piggy-back. I presume they are mating or about to do so.
Created 20 April 2009
Updated 5 November 2021