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A love dart from the land snail Monachoides vicinus

A love dart is a hard, sharp, calcareous or chitinous dart which some hermaphroditic land snails and slugs create. Love darts are made in sexually mature animals only, and are used as part of the sequence of events during courtship before actual mating takes place.

Prior to copulation, each of the two snails (or slugs) attempt to "shoot" one or more darts into the other snail (or slug). There is no organ to receive the dart; this action is more analogous to a stabbing, or to being shot with an arrow. The dart does not fly through the air to reach its target however; instead it is fired as a contact shot.

The love dart is emphatically not a penial stylet (in other words this is not an accessory organ for sperm transfer). The exchange of sperm between each of the two land snails is a completely separate part of the mating progression. Nevertheless, recent research shows that use of the dart can strongly favor the reproductive outcome for the snail that is able to lodge a dart first in its partner. This is because mucus on the dart introduces a hormone-like substance that allows far more of its sperm to survive. (Read more...)