Opisthobranch of the Week Data
Gymnodoris aurita is considered to be very rare on Okinawa. As of this date I've not personally found this beautiful gymnodorid; the above featured animal is one which was photographed here by Mr. Yokoi Kensuke of the "Blue Try" SCUBA & U/W Photo Shop, and his photograph of the animal is used here with his kind permission.
G. aurita is the only described, large reddish species of Gymnodoris having prominent tubercles (Gosliner & Behrens, 1997). In their redescription of the species, Gosliner & Behrens (1997) report that the animal is found on shallow reefs from Fiji to the Philippines and Indonesia and that the species has a firm body reaching over 100mm in length.
Writing in Mike Miller's Slug Site, Dave Behrens points out an interesting common name for this beautiful animal.
Prior to the confirmation of the identification of this species a small group of Philippine nudibranch enthusiasts referred to the animal as Gymnodoris "rex" due to its similar voracious feeding posture with that of the dinosaur Tyrannosaurus rex. Active nocturnally, Gymnodoris [aurita] has been observed rising up over its prey in a fashion similar to T. rex attacks seen in the movie Jurassic Park. An opisthobranch predator, it has been observed feeding on tritoniid nudibranchs of the genus Marionia (Mark Prein, pers. comm.).
I've included an additional photo of the same Okinawa specimen, showing another view of the huge spectacular gills.