>I am doing research for my masters on Naineris dendritica, Orbiniidae, and
>have found some of them so plugged up with sand in the posterior segments
>that they tend to break very easily when being cleaned or on their own
>naturally. Evolutionarily this would be selected against, so it may be a
>case of a bad combination of too many silaceous diatoms injested with the
>sand. It made me think of your correspondence with Jerry McLelland last
>month regarding the same problem in the Aricidea. The nainerid gut appears
>to be susceptable to plugging from its morphology, possibly the Aricidea gut
>and diet are similar to Naineris dendritica. .
>John Weaver
>Biolgy Department
>Humboldt State University
>jkw1 at axe.humboldt.edu>>Sounds like the same thing. Our paper (which describes a new species of
Aricidea in the subgenus Allia) is now published in Gulf Research Reports
(vol. 9, no. 3, pages 189-196). We mentioned this sand-filled gut in the
paper. I suspect, at least in the case of Aricidea, that the worm lives
only a short time (1 year) and they simply accumulate sand the entire time.
It may have some benefit (deter predation, increase surface area of
digestion, help anchor the worm in the tube), but I remain unconvinced.
Someone else might have an idea, but I have not heard a plausible one.
Gary R. Gaston
Biology Department
University, Mississippi 38677
(601) 232-7162
