re: Bubble shell from Kerama Id

February 4, 2000
From: C. Carlson & P.J.Hoff


Mr. Ono's bubble shell is probably Ventomnestia villica (Gould, 1859).

I have attached some examples from a breeding population which gives some idea of the variation that may occur. A common form not shown has a single red line. Ventomnestia villica may be the same as V. bizona (A. Adams, 1850). The only wet material we have for V. bizona is a small juvenile from Bali and have not yet tried to make any internal comparisons.

Ventomnestia has a fairly heavy shell, gizzard plates with 6 to 7 heavy ridges covered with rods. The radula formula for villica is 2.1.2. One characteristic of the haminoeids is the absorption of all but the outer 1 1/2 whorls of the shell. This is also true of V. villica, except that the periostracum has been retained so that the liver remains coiled.

Earlier studies based upon shell alone had Ventomnestia as a cylichnid or retusid form. It is a good example of the need for wet material (e.g. living/preserved from living specimens) in the study of the
bubble shells.

PHOTO DETAILS: c.27; Guam, Toguon Bay, 8m; 27 May 1993. [the average size of the animals we have measured is a little over 4mm -- the largest 5.5mm. we don't look for largest and smallest so there are probably larger forms around.]

Clay & Patty Jo.

Carlson, C. & Hoff, P.J., 2000 (Feb 4) re: Bubble shell from Kerama Id. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Clay & Patty Jo,
Thanks for your help. As you say, we definitely ned to know more about the animals.
Bill Rudman.

Related messages

  1. Re: Ventomnestia
    From: Erwin Koehler, February 9, 2000
  2. Bubble shell from Kerama Island
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