Episode 420: The Sea Bunny

Thanks to Sam for suggesting this week’s topic, the sea bunny! My plush sea bunny, with one of my cats, Dracula, who does not like it: Show transcript: Welcome to Strange Animals Podcast. I’m your host, Kate Shaw. This week we’re going to revisit an animal we haven’t talked about in a few years! Thanks to Sam for suggesting it, and for sending a whole list of questions after listening to episode 215. Episode 215 was about the cutest invertebrates, and we talked about a lot of them. This week it’s all about the sea bunny. Before we answer Sam’s questions, let’s go over what we learned in episode 215, in case you haven’t listened to it since it came out in March of 2021. The sea bunny, or sea rabbit, is a type of nudribranch [noodi-bronk] that lives along the coastline of the Indo-Pacific Ocean, especially in tropical waters. Nudibranchs are a type of mollusk that are sometimes called sea slugs. Many are brightly colored with beautiful patterns. Compared to some sea slugs, the sea bunny is a little on the plain side. It’s usually orange or yellow, sometimes white or even green, with tiny brown or black speckles. It looks fuzzy because it’s covered in little protuberances that it uses to sense the world around it, as well as longer, thinner fibers called spicules. It also has two larger black-tipped protuberances that look for all the world like little bunny ears, although they’re actually chemoreceptors called rhinophores. It has a flower-shaped structure on its rear end that looks kind of like a bunny tail, but it’s actually gills. It really is amazing how much the sea bunny actually resembles a little white bunny with dark speckles. Like other nudibranchs, the sea bunny is a hermaphrodite, which means it produces both eggs and sperm, although it can’t fertilize its own eggs. When it finds a potential mate, they both perform a little courtship dance to decide if they like each other. After mating, both lay strings of eggs in a spiral pattern. The eggs hatch into larvae that are free-swimming, although the adults crawl along the ocean floor looking for food. Some nudibranch larvae have small coiled shells like snails, which they shed when they metamorphose into an adult, but the sea bunny hatches into a teeny-tiny miniature sea bunny. One of Sam’s questions was what the sea bunny eats. It mainly eats sea sponges. The toxins present in many sponges don’t bother the sea bunny. Instead, the sea bunny absorbs the sponge’s toxins and keeps them in its body. I don’t usually bother with Reddit posts while researching episodes, but I saw one where people were discussing how toxic the sea bunny is. Someone pointed out that small as they are, it’s not a good idea to pick up a sea bunny because they are so toxic, and someone replied, “That’s good for them, because I’m going to assume they taste like Marshmallows.” That brings us to Sam’s next question, does anything eat the sea bunny? That’s mainly a no, because they are so incredibly toxic. An animal the size of a big shark or something like that probably wouldn’t be affected by the sea bunny’s toxins, but it also wouldn’t bother with such a tiny snack. A fish or other animal small enough for the sea bunny to seem like a meal probably wouldn’t survive its toxins. Sam also wants to know if the sea bunny travels in groups, and that doesn’t seem to be the case. It’s a mostly solitary animal most of the time. If it did gather in a group, say if a bunch of sea bunnies were munching on the same sponge at the same time, maybe we could call it a fluffle of sea bunnies, or a school of sea bunnies. Sam also wants a better idea of how small the sea bunny is. It’s easy enough to say, oh, it’s a little less than an inch, or around 2 ½ cm, but most of us have a hard time picturing that. So here’s a comparison that will help you visualize it. If you have an ordinary paperclip, not one of the jumbo ones, it’s usually around 2.5 cm long, maybe just a bit bigger. So a big sea bunny is just barely the length of an ordinary paperclip. Sam’s last question is one of the most important ones, and I bet at least some of our listeners are wondering the same thing. Can you keep a sea bunny as a pet? The answer is no, sorry! Aside from the sea bunny being really toxic and not safe for your other aquarium pets or you, it would need care that’s hard for a home aquarium keeper to provide. Some experienced saltwater aquarium keepers do have some types of sea slugs, but not typically sea bunnies, not even big professional aquariums. Fortunately for all of us, sea bunnies are popular enough these days that you can get a sea bunny plushie. I know because I have one—and I found it just two days ago as this episode goes live! I was looking through the half-priced Valentine’s Day stuff on February 15 when I found a stuffy that looked just like a sea bunny. I picked it up and sure enough, it was a sea bunny, and it was on sale! There’s a picture of it in the show notes. It’s a lot bigger than a real life sea bunny, but it’s also not toxic. You can find Strange Animals Podcast at strangeanimalspodcast.blubrry.net. That’s blueberry without any E’s. If you have questions, comments, or suggestions for future episodes, email us at [email protected]. We also have a Patreon at patreon.com/strangeanimalspodcast if you’d like to support us for as little as one dollar a month and get monthly bonus episodes. Thanks for listening!