Volvatella ayakii Hamatani, 1972 (3.5mm / shell)
OPISTHOBRANCH OF THE WEEK
Photo by Atsushi Ono
Opisthobranch of the Week Data
Frequency on Okinawa:
- Order: SACOGLOSSA
- Family: Volvatellidae
[brackets indicate range for all Okinawa-collected specimens of the species]
- Individual Collection No: photo only, w/o specimens
- Location: Zamami Island, Kerama Islands, Okinawa
- Date: June, 2000 [photo only, w/o specimens]
- Depth: 33ft (10m)
- Water temperature at collection depth: ca. 79oF (ca. 26oC)
- Size: TL 3.5mm (shell)
- Specimen deposited: Photo only, without specimen
Volvatella ayakii is considered to be very rare in Okinawan waters; I've not personally seen this attractive little volvatellid here in the waters of Okinawa's main island and Atsushi mentions (pers. comm.) seeing only the above single uncollected individual in the Keramas.*
Atsushi reports that it was found amid seaweed associated with a mooring chain associated with a buoy.
I've previously featured one other described species of Volvatella on these pages, V. angeliniana, from Okinawa's main island. In addition to the two described species from Okinawan waters (V. angeliniana and V. ayakii), I've also found an undescribed(?)
green-shelled animal and a brown-shelled animal. Ichikawa (1993) found two additional Volvatella here: 1) Volvatella viridis, described by Hamatani (1976) from Japan, and 2), an undescribed species, but different from the unknown green-shelled specimens I've collected.
Bill Rudman (2002) and Jun Imamoto (2004) have a series of excellent photographs of Volvatella ayakii posted on their sites.
- Ichikawa, M. 1993. Sacoglossa (Opisthobranchia) from the Ryukyu Islands. Publ. Seto Mar. Biol. Lab. 36(3): 119-139.
- Imamoto, J. 2004. Taxonomy list with links to photos, available from
- Hamatani, I. 1976. Preliminary account of a new species of Volvatella Pease, 1860, V. viridis sp. nov., found in the caulerpan microfauna in Japan. Publ. Seto Mar. Biol. Lab 22(6): 371-376.
- Rudman, W.B. 2002 (March 17). Volvatella ayakii. Hamatani, 1972. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet.cfm?base=volvayak
* Keramas = the Kerama Islands Group, located 30 ~ 40 kilometers west of the Okinawa capitol, Naha.
Page Date: 29 Nov '04
Page Modification Date: 06 Jun '05
Digitally manipulated photo (image has been horizontally flipped)
Copyright © 2005 Robert F. Bolland