Opisthobranch of the Week Data
Embletonia gracilis is considered to be rare in Okinawan waters; I've not personally observed this uncommonly seen aeolid in the waters of Okinawa's main island, however, Atsushi Ono reports the above featured animal is one of over 10 individuals (two of which have been collected) which he has seen in the Keramas* (per. com.). The featured animal was collected by Atsushi in December of 1998 from beneath live coral, Porites (?) spp.
E. gracilis was initially reported in Japan by Baba (1959, as E. gracile**) and Baba lists the collection of three specimens (3~8mm) from Sagami and Osaka Bays in mainland Japan. It's perhaps interesting to note that Baba (1959) mentions the shape of the mainland Japan specimens are fusiform and short in contraction, but they may extend greatly. Ono (per. com.) mentions that the above featured animal, while alive, was measured with its maximum length noted to be 40mm, but shrinking to 15 mm.
Gosliner (1987) reports finding the species in the intertidal zone, where it feeds on campanularid hydroids, under rocks.
* Keramas = the Kerama Islands Group, located 30 ~ 40 kilometers west of the Okinawa capitol, Naha.
** Baba & Hamatani (1963) revised the name used in Baba's 1959 publication to E. gracilis.