Re: Philine orientalis? from Singapore

Dear Kok Sheng,

It is hard to be sure of its identification without looking at least at its internal shell and gizzard plates, but as I said in Dong Bum Koh's message, this muscular, wedge-shaped body form is only found in a few species, including P. orientalis.

For those unfamiliar with species of Philine, your upper photo shows an animal burrowing into the sandy bottom. The wedge-shaped and muscular body are modified for this burrowing life. The front end of the body, including most of the head shield and flanking parapodia are almost totally buried, while the 'posterior shield' with the bright white internal shell are still visible.

The middle photo shows the ventral side of an animal which has been lying on its back and has just buried its head [right end of photo] in the sand and I assume is about to flip over before completely burying itself. The lower photo is a close-up of part of the ventral photo and I have labelled a few of the body parts. As in many cephalaspideans, the foot does not extend to the posterior end of the body, usually the most posterior part of the body is the shell. In species, such as Philine, in which the shell is internal we call the part of the body that encloses the shell and the remnant mantle cavity the posterior shield. In the lower photo we can see how the posterior shield folds under to form to lobes which enclose the mantle cavity and gill. I have arrowed the opening through which water is drawn inot the mantle cavity.

Best wishes,
Bill Rudman