The Naked Textile Cones

     Keeping a marine aquarium at home can be fascinating and sometimes reveals amazing behavior of its inhabitants. Recently, a strange event took place at the home of Maj. and Mrs. H. J. Bartell of Foster Village here in Hawaii. The Bartells and their three sons have kept several Conus textile alive in their aquarium for months, feeding them various mollusks which they collect from areas around Oahu. The boys have watched the C. textile sting and eat their prey, and once even saw a couple of cones mating and then laying eggs. But this didn't seem to unusual to the boys. What happened on February 22nd was unusual though.

     For no apparent reason, one of the C. textile squirmed and unwound itself out of its shell. It was quite active for 4-5 days, crawling over the sand and up the sides of the aquarium, but it refused to eat. It died after being naked for 7 days, during which time it never made any attempt to get back into its shell that lay nearby. Shortly after the first C. textile discarded its shell, a second one decided to try it. It began to slowly squirm its way out its shell at about 10 in the morning but never got completely out. It died in about 6 hours.

     The Bartells have two other C. textile in the aquarium which lived with the ones that preferred a naked existence, but these two "sensible" cones like having their protective shells around them, and they are still very much alive and healthy.

     The photos of the "Naked Textile" were sent to Dr. Alan J. Kohn, Department of Zoology, University of Washington for examination and possible explanation of this remarkable occurrence. Dr. Kohn answered: "I have never observed the phenomenon of a Conus leaving its shell, nor do I have an explanation. Some adverse conditions must have caused the junctions of columellar muscle and shell to weaken. There are a few recorded cases of living Littorina littorea observed without shells in nature; I cannot put my hands on the reference, however. I have enclosed a diagram ... indicating the visible anatomical features.

Visible organs of the Shell-less Conus textile (osphradium, gill and its blood vessels, and hypobranchial gland are on the underside of the mantle but can be seen through it.)

*Adapted from an article by Olive Schoenberg published in Hawaiian Shell News, New Series No. 127, July 1970, VOL. XVIII No. 7. Photographs by the author.

**Thanks to Mr. Bob Dale for both locating and scanning the material from Hawaiian Shell News.