The nudibranch, whose name literally means “naked gills,” is a shell-less snail species. It has the appearance of a slug but with much more mobility as it propels itself through powerful undulations of its body. This sinuous movement and the vibrant colors of its mantle have given one of the species the nickname “Spanish dancer.”
At first glance, one might think it is an easy prey, but that is not the case. The nudibranch lacks its own weapons to ensure defense against predators, so it must find someone to provide them. With this in mind, the nudibranch seeks out an anemone, immobile animals that live attached to the seabed and are known for their stinging cells. The nudibranch is not only immune to the powerful venom of the anemones but also accumulates the venom in its gills. This venom then functions as a stinging weapon that attacks any animal that tries to eat it.
The reproduction of nudibranchs is no less spectacular. They are hermaphrodites, meaning each individual carries both eggs and sperm simultaneously. When two nudibranchs encounter each other, they can copulate and mutually fertilize each other, resulting in both of them having offspring. Hermaphroditism increases the reproductive potential of the species since all individuals can produce offspring, rather than just half of them. In the case of nudibranchs, the newborn already possesses venom transmitted by its parents, allowing it to defend itself until it finds its own anemone.
Perhaps the most astonishing fact is that nudibranchs do not consume the entire anemone but rather settle for consuming one or two of its arms, which the anemone can easily regenerate without any issues. The reason behind this behavior is a question that scientists have been trying to answer for many years. Perhaps the limited stomach capacity of the nudibranch prevents it from engulfing an entire anemone.
Alternatively, it is possible that the nudibranch wishes to keep the venom-supplying source alive, which will keep it alive as well. This might be a very complex reasoning for a snail, a reasoning that humans seem not to apply or at least not understand. It remains a mystery to be solved.
“One cannot defend what one does not love, and one cannot love what one does not know.”