09 April 2005

The dissection selection: Philomycus carolinianus

The pulmonate land snails have evolved all sorts of complicated genitalia and unusual mating rituals. The largest group of pulmonate land snails is the Stylommatophora, in which the eyes are located on the tips of the upper (longer) tentacles. Several families in the Stylommatophora, including the Helicidae, Zonitidae and Philomycidae, have evolved darts to stab each other with during mating. The presence of darts in many distantly related families of the Stylommatophora strongly suggests that darts were also present in the ancestors of the Stylommatophora1.

The Philomycidae is a family of slugs that are native to the United States. One member of the family, Philomycus carolinianus, a common slug in northeastern forests, has a thick, curved dart kept in a muscular sac. The top picture on below shows the components of the hermaphroditic reproductive system of P. carolinianus, while that on the bottom shows its dart, which was about 2.7 mm (the ruler, in millimeters, is for the left photo). The head of the dart broke while I was trying to remove it, but now we can see the shape of its cross-section.



Glenn Webb2 once dissected a pair of these slugs that he had killed while they were still mating and published, to my knowledge, the only account of how the dart functions during the mating of these slugs: "...the dart was found to have been thrust sufficiently far into the proximal or basal part of the inserted penis to form a definite wound..." Talk about painful sex!



1. Barker, G. M. 2001. Gastropods on Land: Phylogeny, Diversity and Adaptive Morphology. In The Biology of Terrestrial Molluscs, edited by Barker, G. M. CABI Publishing.
2. Webb, G. R. 1968. Observations on the Sexology of Philomycus carolinianus Bosc. Gastropodia 1:62.

5 comments:

Anonymous said...

Let me be the first to say (anything, really) that I am very impressed! Not only with the Tales of the Snails, but with your ability to get those little dots over the O's!!! Way to Go!
Z.
P.S....The photo is really YOU!

Arzu said...

Snails had tails to tell! Aydın, thanks for bringing such a special knowledge to the table. Enjoyed both the images and the text. Bookmarked, will be revisited.

deniz bevan said...

see, see, that's what I mean!!! "tales" not "tails"!!! ouch!!!

deniz bevan said...

How could he kill them while they were having sex? How would he like it if someone did that to him?

The Snailwatcher said...

I dont't know,but at least he would die with a smile on his face.