Starring in episode 53 of “Take a Minute to Relax” is a bundle of cuteness that is commonly known as a “sea bunny”, whereas scientists like to name it “Jorunna parva”. This little fluffball is obviously not related to any land-dwelling bunnies. It is, in fact, a species of dorid nudibranch, a shell-less marine gastropod mollusc in the family Discodorididae. This species is on average about 1 cm long, and the black protrusions on its head are somewhat similar to a rabbit’s ears. This resemblance facilitated a surge in popularity on Twitter throughout Japan in 2015.
The „ears“ of the sea bunny
The two little “ears” that make these sea creatures look like bunnies are in actuality sensory organs called rhinophores. They help the nudibranch detect chemical scents in the water column, allowing them to find food, as well as potential mates. In the world of nudibranchs, Jorunna parva’s rhinophores are particularly fuzzy, allowing for more surface area to facilitate better scent reception. In fact, sea bunnies are effective at detecting scents over surprisingly large distances, especially considering how small they are.
Colourful „coat“ of Jorunna parva
The so-called yellow fur coat you see on the sea bunny can actually range in colour from white to orange or even brown and green. It is, however, most definitely not fur. What we observe are groups of small rods known as caryophyllidia covering the nudibranch’s back. These are arranged around small black specks that give the Jorunna parva its spotted look. Most experts believe that these organs play a sensory role. The external gills of this creature are located near the back of its body. There is controversy over whether or not the different colourations of sea bunnies are different species altogether.
Toxic sea bunny
Like most other members of its genus, the sea bunny’s diet consists of sponges in the family Chalinidae. These sponges contain toxins which Jorunna parva stores in its tissue as a defence from would-be predators. Same as with many other nudibranchs, this toxicity is advertised through its bright colours. Most predators, therefore, stay well away from this cute-looking toxic “bunny”.
Short and sweet
The average lifespan of a Jorunna parva is only between a few months to a year. Because of their short lifespan, typically isolated lifestyle and slow-moving pace, mating is by no means guaranteed. If and when the opportunity arises, it must be taken advantage of. This explains why it is so very important for this creature to have such a well-developed sensory system. After all, only this way they are able to locate one another.
Sex in the sea
Like all nudibranchs, sea bunnies are hermaphrodites, meaning that they have both male and female reproductive organs. They mate by exchanging sperm with one another to fertilize the eggs of the partner. Therefore, they are both mothers to their own children and the father of someone else’s, while both their offspring are direct siblings. One big happy family …
What a beautiful and diverse world we live in!
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