Discover Sea Bunnies, Nature’s Cute Yet Toxic Sea Slugs

Sea bunnies, whose scientific name is Jorunna parva, are a species of soft-bodied, shell-less, marine-based slugs. They were first described in the 1930s by Japanese zoologist Kikutaro Baba. The cute, fluffy, and wiggly little marine organisms recently rose to prominence on social media when people began to notice their resemblance to a rabbit. However, what exactly is a sea bunny? Keep reading to learn some unbelievable facts about these intriguing creatures.

What Is A Sea Bunny?

The sea bunny is a species of dorid nudibranch, which are diverse organisms in striking colors and exotic forms. They are native to the coastal waters between the Indian Ocean and the Central Pacific. Sea bunnies are less than one inch long and are most commonly found in orange or yellow. Popular images show the more bunny-like black-and-white color that is typically found off the coastal waters of Japan.

Much like other slugs, the sea bunny is thought to begin its life with a shell that it sheds sometime before reaching adulthood. The furry-looking “coat” actually consists of tiny rods called caryophyllidia. Some of these rods end in black knobs, giving the sea bunny a speckled appearance. The “ears” are two long antennae called rhinophores that have small flaps emerging from the sides. The sea bunny’s gills are located on the backside, emerging outward like a tail, which is a distinguishing feature of dorids.

Their Bodies Are One Big Sensory Instrument

The sea bunny is covered in sensory organs. The two antennae-like rhinophores emerging from the head are arranged in such a way as to maximize the surface area of the sensory receptors. These structures help sea bunnies navigate, detect predators, find food, and determine the direction of currents.

The caryophyllidia rods that cover the body like fur are likewise thought to play a sensory role. However, researchers are not yet sure what that role is. Some scientists believe the rods act as a sense of smell. Sea bunnies do not have eyes or ears, so the rhinophores and the caryophyllidia serve as the slug’s means of sensing the environment.

The Sea Bunny Is a Hermaphrodite

Most sea slugs are hermaphrodites, with both male and female sexual organs. This does not mean the sea bunny can self-fertilize, however. They still mate by exchanging their sperm with another sea bunny to fertilize their eggs. The sea bunny has a long spine that digs into the partner so the two remain attached until the exchange is over.

All mating opportunities must be condensed into the sea bunny’s short lifespan, which probably lasts for no more than a few months to a year. This means the sea bunny must mature quickly and reproduce as frequently as possible. Their well-developed sensory organs help them locate other sea bunnies in the wild.

Sea Bunnies Are Highly Toxic

After losing its protective shell early in its life cycle, the sea bunny has only a single defensive mechanism to prevent it from being eaten. Fortunately, it’s a very good one. The sea bunny is highly toxic. However, the sea bunny does not produce the toxins by itself. Instead, it acquires the toxin by feeding on sponges and absorbing those toxins for its own use.

This toxin may also have pharmacological applications. Dorid nudibranchs are toxic due to their diet. However, some of these toxins have helped treat cancer in humans.

Do Sea Bunnies Make Good Pets?

While some owners of saltwater aquariums attempt to keep a few varieties of sea slugs as pets, it’s a very challenging task and is recommended only for experienced aquarists. Sea slugs have voracious appetites, and their required diet of prey species is very limited. Unfortunately, it’s easy to inadvertently starve them to death. In the case of sea bunnies, they are not recommended as pets because of the threat they pose to other creatures in the aquarium.

Sea bunnies might share a faint resemblance to rabbits, but that is where the similarity ends. These are saltwater sea slugs who prey on other sea creatures, particularly sponges. Given that their diet of sea sponges also makes them toxic to other animals, you certainly would not want to try to cuddle with sea bunnies. Those toxins might be useful in the fight against cancer someday, but that is a long way off. These cute critters are best left to themselves and enjoyed from afar.