The mating ritual of Sea hares

The Aplysiomorpha is commonly known as Sea hare, due to its rounded shape and the sensory appendix on top of its head (called rhinophores) which resembles the ears of a hare. The Sea hare is a type of sea slug, but it is generally larger than slugs, reaching up to 20 cm in length. The largest species, Aplysia vaccaria, can reach a length of 75 cm and a weight of 2 kg, being the largest gastropod species. These creatures have invented a chemical aphrodisiac that helps them mate; seen as how they are hermaphrodites who cannot fertilize themselves, they have long orgies in order to reproduce.

The actual pheromone is unimaginatively called “attractin” and it is between 100 and 1000 times stronger than any human hormone. Given that Sea hares have poor sight and their life expectancy is of only one ear, it is crucial to them to find a mate. And they do. Dr. Nagle said the following: “between two animals, mating can go on for several hours. But in a group of 15-20 animals, mating can go on for several days, so it is a long term party. Once the party has started, it goes on and on… ”

You might wonder why this phenomenon is so unusual, since many animal species have multiple partners. Generally, in such cases the male mates with one females and moves on to the next. But as far as the Sea hares, which is hermaphrodites, are concerned, once they have joined the party, they act as males and produce sperm. When sperm is no longer available, they reverse their orientation and act as females, laying eggs that other Sea hares fertilize. And as they jump from one orientation to the other, more of this aphrodisiac fluid is released, which in turn attracts more Sea hares that join in.

Often they form chains of three or more mating partners, with the female on one end, the male on the other and the ones that change orientation in between. While it may be true that we humans have a complicated sex life, as do other animal species, we would most likely be overwhelmed if we attempted to participate for days to an end in such an orgy, despite having the ability to switch from one orientation to the other. If during this mating orgy they are attracted by predators, the Sea hares have a very efficient defense mechanism: they acquire a horrible taste and spew a violet substance over the attacker.  The Sea hares are truly determined to pass on their genes.

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