Sea hare is the common name for several species of gastropod molluscs, belonging to the order Opisthobranchia, and found within the genus Aplysia spp. These are medium to large-sized animals with a very peculiar appearance, since they have “ears” that are reminiscent of a hare, hence their common name. These ears are rhinophores, which as antennae function as sensory organs.
They are herbivorous and hermaphroditic animals, with striking colors and designs, ranging from brown to black, and pink with spots in some species. They move by crawling along the seabed and some have developed wing-like parapodia that also allow them to swim short distances. Continue reading this file on our site and you will learn all about the common sea hare
Characteristics of the Common Sea Hare
The Common Sea Hare (Aplysia dactylomela), also known as Spotted Sea Hare, is a very striking-looking animal, as it appears to be gelatinous and soft. Compared to other species, they are small in size, generally measuring about 7 cm, but can reach up to 20 cm. They have a shell like other molluscs, but in this case it is internal and very reduced, being almost non-existent in adult individuals of some species.
They also have a foot (the body base) that in the middle of the body widens and bends upwards, forming the characteristic parapodia, which in some species are highly developed and similar to wings, being able to surround its entire body, but which, unlike other species, does not allow it to swim short distances. Its head, as we mentioned, has two rhinophores and the eyes are located in a basal and frontal position.
The name opisthobranchs refers to the fact that their gills are located backwards, unlike other molluscs that have them forward. In addition, sea hares have lost their left gill throughout their evolution, and all their representatives are marine species.
Its color varies from black to olive green, to maroon in some individuals, with spots around the body. The pigmentation of their body is given by food, so it varies depending on the stage they are in and the type of food they consume.
Habitat of the common sea hare
The common sea hare is found mainly in shallower waters to no more than 5 meters deep, where the bottom is sandy and muddy, with very abundant algal vegetation. Generally, during the day their activity is less and they take refuge in calmer and shady areas, and at night is when their activity is greater and they dedicate themselves to grazing algae, especially those of the genus Ulva spp., their favorite in areas of the Mediterranean.
In the case of younger individuals, it is more common to observe them at greater depths, where the red algae vegetation is greater.
Customs of the Common Sea Hare
Spotted sea hares move elegantly thanks to their parapodia, which move by undulating and contracting. When they need to position themselves more aerodynamically, their foot is placed longitudinally and the rhinophores facing backwards. In general, their greatest peak of activity is at night. Facing predators or if they are disturbed, not having lost the protection afforded by a hard shell, they have the ability to secrete a dark substance that allows them to mislead their predators.
Feeding of the common sea hare
They are herbivorous animals that feed mainly on macroalgae of the genera Ulva, Laurencia, Gracilarias, and Enteromorpha. Juveniles, as we mentioned, feed mainly on red algae, while adults consume green algae(and therefore the coloration of its body changes with age). Sea hares play important roles in maintaining algae, which, were it not for them, would grow excessively.
Reproduction of the common sea hare
These animals are hermaphrodite and oviparous, that is, they have both sexes in the same individual and also lay eggs. They generally breed throughout the year, but spring is their optimum time. So, depending on the occasion, an individual can act as a female or as a male. It is common for them to form aggregations of several specimens that copulate in a chain, where male and female individuals alternate for insemination to occur.
They have a seminal receptacle that acts as a deposit to store the eggs, and is the site where fertilization occurs. They mate for several hours and then lay eggs, which are seen as long pinkish and gelatinous strips or cords with thousands of eggs From this emerge a free-living planktonic larva, which then moves to the seabed where it will metamorphose and become a juvenile with the typical shape of the sea hare. Its life cycle is complete when it reproduces. Therefore, normally after the laying of eggs they die.
Conservation status of the common sea hare
This species of sea hare is not listed by the IUCN, nor is it protected by any law. However, like other species of sea hare, they face several threats, mainly due to the fragmentation and loss of their habitat and illegal hunting for human consumption, which could endanger their future..
