Ready to learn about one of the cutest sea creatures of all time? Meet the sea bunny! While this animal’s scientific name is Jorunna parva, it has been dubbed the sea bunny slug due to its resemblance to a fluffy white bunny rabbit.
What is a sea bunny?
Sea bunnies are actually a species of sea slug, or nudibranch, and were first described by renowned Japanese marine biologist Kikutaro Baba. Long before sea bunnies became quite the viral video sensation in 2015, these unique ocean animals have been hippity-hopping around the waters of the Indo-Pacific Ocean. To spot a sea bunny underwater, you’ll have to look very closely, as they are typically less than one inch long.
1. That’s Not a Fur Coat
Sea bunny anatomy can be a little deceptive. First off, the white fur coat you see on these sea slugs can actually range in color from yellow to orange to even brown. Secondly, it’s definitely not fur. What you’re looking at are groups of small rods known as caryophyllidia covering the nudibranch’s back. These are arranged around small black specks that give the sea bunny its spotted look. Most experts believe that these organs play a sensory role.
2. Sea Bunny Ears Are Actually Sensory Organs
The two little “ears” that make these sea creatures look like bunnies are actually sensory organs called rhinophores. They help the sea bunny to detect chemical scents in the water column, allowing them to find food and also potential mates. In the world of nudibranchs, sea bunny rhinophores are particularly “fuzzy”, providing more surface area for reception to occur. In fact, sea bunnies are effective at detecting scents over surprisingly large distances—especially considering how small they are.
3. Sea Bunnies Are Hermaphrodites
Like all nudibranchs, sea bunnies are hermaphrodites, meaning that they have both male and female reproductive organs. They mate by both exchanging sperm with one another to fertilize their eggs. Therefore, they are both mother to their own children and the father of someone else’s, while both their offspring are direct siblings.
4. Predators Don’t Like Their Toxins
Predators stay away from these cute little slugs because they are incredibly toxic. Just how poisonous are sea bunnies? Well, that depends on their diet. The sea bunny slug belongs to a group of sea slugs called dorid nudibranchs, which steal toxic defenses from their food. They often eat food like sponges that contain toxins.
5. A Sea Bunny Lifespan is Short
The average lifespan of a sea bunny slug is only a couple of months to a year. Because of their short lifespan and typically isolated lifestyle, mating is not guaranteed and must be taken advantage of when the opportunity arises. This is also why it’s so important they have such a well-developed sensory system to be able to locate one another.
6. Sea Bunnies Are What They Eat
Unlike their land-based namesakes, sea bunnies are carnivores that like to snack on other sea slugs or sea snails. They also use a special feeding organ (called a radula) to scrape off and eat algae from ocean surfaces. However, toxic sea sponges make up the majority of a sea bunny diet. As well as retaining the toxins for their own defense, these sea slugs also absorb the pigments and will change appearance based on what they eat.
7. Sea Bunnies Start Out Life With a Shell
After hatching, the free-swimming larva of a sea bunny has a shell—a characteristic common to all mollusks. Eventually, during a process called metamorphosis, it sheds this protective layer and emerges as the bunny-like sea slug we know and love. This transformation is the same for all nudibranchs, whose name aptly means “naked gills”.
8. Sea Bunnies Are Part of a Bigger, Fascinating Family
The sea bunny species is part of the family Discodorididae, which in turn belongs to the order Nudibranchia. It’s a huge family, with around 3,000 known nudibranchs. Many other types of sea slugs are just as weird and wonderful as their cute sea bunny cousins. For example, there are blue dragons, flamenco-like Spanish dancers, suitably named “leaf sheep“, and even one that runs on solar power!