Snails are hermaphrodites and they have a very complicated sex life. Most interesting to me is the
fact that snails shoot sharp ‘love’ darts at each other before mating. The darts do not prevent mating, nor do they encourage mating. Why, then, do they shoot darts? The question had been asked for hundreds of years.
We found that the dart functions after copulation to increase the reproductive fitness of the shooter. Snails are promiscuous, and sperm donors (‘males’) compete with each other to fertilize the eggs of sperm recipients (‘females’). Landed darts promote the safe storage of the shooter's sperm, thereby increasing the chance that sperm from the successful shooter - rather than from the unsuccessful shooter - will be used for fertilization. Indeed, we found that successful dart shooters sire more babies than unsuccessful dart shooters.
We tested whether the dart works by rupturing the skin or by injecting a bioactive agent. Just before the dart is ‘shot’, it is covered with mucus from a special gland located near the dart's launching site. We hypothesized that the dart works by injecting this mucus. Our test involved needle stabbings substituting for dart shots. In some trials, saline was injected through the needle; in the other trials, mucus was injected. We found that mucus injections doubled the number of offspring compared to saline injections. Thus, mucus is the agent of the dart’s effect on reproduction.
fact that snails shoot sharp ‘love’ darts at each other before mating. The darts do not prevent mating, nor do they encourage mating. Why, then, do they shoot darts? The question had been asked for hundreds of years.
We found that the dart functions after copulation to increase the reproductive fitness of the shooter. Snails are promiscuous, and sperm donors (‘males’) compete with each other to fertilize the eggs of sperm recipients (‘females’). Landed darts promote the safe storage of the shooter's sperm, thereby increasing the chance that sperm from the successful shooter - rather than from the unsuccessful shooter - will be used for fertilization. Indeed, we found that successful dart shooters sire more babies than unsuccessful dart shooters.
We tested whether the dart works by rupturing the skin or by injecting a bioactive agent. Just before the dart is ‘shot’, it is covered with mucus from a special gland located near the dart's launching site. We hypothesized that the dart works by injecting this mucus. Our test involved needle stabbings substituting for dart shots. In some trials, saline was injected through the needle; in the other trials, mucus was injected. We found that mucus injections doubled the number of offspring compared to saline injections. Thus, mucus is the agent of the dart’s effect on reproduction.
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During courtship, the snail at the top shot a dart through its partner. Afterwards they copulated.
Snails lay eggs in subterranean nests.