October 20, 2001
From: John Chuk
The recent messages and wonderful pictures of juliids from Hawaii have inspired me to scan some slides of what I think is Tamanovalva babai taken at Rickett's Point, Melbourne (Australia) in February 1999. The specimens were photographed close to shore in 2m of water. They have been observed in abundance at this site over the summer months for several years. Despite their abundance they are easy to miss as they are minute (with a maximum shell dimension of 4mm) and are very well camouflaged. The shell closely resembles, in shape and colour, the ramuli of the green alga, Caulerpa geminata, on which they are found.
The specimens are typically bright green in colour with a bivalved shell of the same colour. They are able to completely withdraw into the shell when threatened. The rhinophores are rolled and are white tipped. The eyespots are located on a small white-tipped, raised tubercle that is situated on the dorsum of the neck some distance behind the rhinophores. The neck and rhinophores have fine white spots on them.
The first image is an in situ lateral view of a specimen (7mm in length fully extended). This shot shows how thin and translucent the shell is as the outline of the neck can be seen through it. The second image is a view of the dorsum of a specimen that shows the bivalved shell. The third image is of rather poor quality but I have included it as it shows a specimen secreting a white solution on being aggravated by yours truly. Possibly a form of chemical defence? I was not tempted to taste it.
The bivalved sacoglossans are rather elegant and intriguing little animals. If any Victorian divers wish to see them then Rickett's point is the place to go. Find a bed of C. geminata and start searching!
Chuk. J., 2001 (Oct 20) Tamanovalva babai from Victoria, Australia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/5505
Yes these are Tamanovalva babai. Cory's Hawaiian photos also were the trigger I needed to prepare some material on the famous three species from south-eastern Australia, Tamanovalva babai, Midorigai australis, and Edenttellina typica.
Thanks for these photos and observations. The white secretions are defensive secretions that many sacoglossans can exude when stressed. At least in some species they appear to be recycled chemicals from their plant food.