Say hello to this week's Internet overlord, the fluffy-looking "sea bunny."
The animal isn't actually a tiny ocean-dwelling rabbit. The creature eliciting "awwws" around the world is a type of sea slug called Jorunna parva.
Most are less than an inch (2.5 centimeters) long and can be found throughout the Indo-Pacific Ocean from South Africa to the central Pacific. Though the most popular images of these animals show white animals with black spots, these sea slugs are usually yellow or orange. (See pictures of other colorful sea slugs.)
Jorunna parva's fur-like coat is due to bunches of tiny rods, called caryophyllidia, that cover the animal's back. They're arranged around little knobs that are sometimes black, giving the sea bunny its speckled appearance.
"We don't know for sure what these organs do," says Ángel Valdés, a sea slug expert at California State Polytechnic University in Pomona. But "they probably play sensory roles."
The sea bunny's "ears," or the two antenna-like structures on top of its head, are most definitely sensory organs. Called rhinophores, they detect chemicals in the water that helps sea bunnies find food and mates, says Valdés.
The rhinophores are covered in little flaps that boost their detection capabilities, allowing J. parva to sense its environment very efficiently.
The structure on the sea bunny's behind that looks like a little "flower" are its gills.
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The sea bunny, like most sea slugs or nudibranchs, is a hermaphrodite. They have both male and female reproductive organs, and when they mate, both partners exchange sperm.
The cuddly-looking creatures come armed with "incredibly long copulatory spines," says Valdés. It's basically like a dart that the animal jabs into its partner during the mating process. This ensures that they stay attached to each other until the sperm exchange is done, he explains. (See "Why Sea Slugs Dispose of Their Own Penises.")
"They probably live just a few months to a year," Valdés says, so every chance they get to mate is important.
Luckily, J. parva doesn't have to worry much about predators during its brief life because "they're very, very toxic," the sea slug expert says. "Anyone who tries to eat them is going to have a very hard time afterwards." (Read about how sea slug chemical blasts deter lobsters.)
Like all the sea slugs in the group containing J. parva, called the dorid nudibranchs, the sea bunny steals its toxic defenses from its food. Dorids eat sponges, and some of their toxins are also used in cancer treatments for people.
Sea slugs in other groups can steal the stingers right out of jellyfish and use them in their own defense. For instance, slugs in the genus Glaucus will attack and eat one of the most venomous jelly-like animals out there, the Portuguese man-of-war.
Admire and coo over the fuzzy little creature now known as the sea bunny. Just resist the urge to touch those rabbit ears.
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