Assorted Sea Slug Facts

So you’ve made it through the entire sea slug series. Or you stumbled upon this and now you’re very confused. Well, I ran out of general sea slug facts, but I know quite a bit about the blue dragon sea slug, so… HERE’S A POST ABOUT THE SEA SLUGS THAT I DON’T KNOW MUCH ABOUT BUT FIND COOL!!

Fun fact #1 (the one before I go off on blue dragon sea slugs): there are two sacoglossan sea slug species (alliterationnn~) that can regrow their entire body from their head. Yes, even the vital organs. This whole regeneration process takes about 3 weeks, 2 weeks less than the amount of time it takes for 5 weeks to pass. These are the Elysia atroviridis and Elysia cf. marginata sea slugs; in case you want to do more research.


THE BLUE DRAGON SEA SLUG (GLAUCUS ATLANTICUS) IS A WEIRD ONE. The little dudes float upsy-downsy on the waves, like discarded plastic. But every once in a while, a jellyfish comes by and the sea slug latches on and consumes it whole. Its favorite jellyfishy is the Portuguese Man o’ War, which is deadly to hoomans. This jellyfish is commonly known as the blue sea taco by a total of two people.

Back to the dragon slugs though. They live in ocean basins mostly, but sometimes they wash up on coasts because they suck at swimming. They’re also teeny-tiny, growing up to only one and a half inches.

Also, I forgot to add this link to the general sea slug post, so here’s a funny video talking about nudibranchs: Click this link, it’s not a rickroll. Enjoy!

Annddd that’s all for the sea slugs, and probably this year unless I get bored.

Stupidly Horrid Sea Hares

Yay. Sea hares.

To properly talk about sea hares, you first must know one thing. Sea slugs evolved from sea snails, so they lost their shells over time. Most sea slugs are actually born with shells but then move out of them in the first few stages of life. But not the sea hare. The sea hare wanted to be a slug, but it didn’t really want to not be a snail. So, it took that lovely shell and shoved it into its body.

Yeah, that’s right – sea hares have an internal shell. This shell encases their vital organs, much like a ribcage except it’s in an invertebrate. Sea hares are also very bland and large compared to other sea slugs.

The only thing saving them from me is the fact that they sometimes look a bit like tacos. They also squirt out purple ink when threatened, much like a squid. Other than that, they are boring.

Above, you’ll find a more accurate picture of a sea hare. I shall now go cleanse my brain of the sea hare by looking at pictures of sea sheep.

Sexy Sacoglossan Sea Slugs

No, I am not a sea-slug-sexual (AKA: SSS, pronounced like someone dropped a hot coal into your mouth), I just love sacoglossan sea slugs and alliteration.

Sacoglossans are part of the sea slug clade Sacoglossa and are also known as “sap-sucking slugs”. They gained this delightful title by eating a lot of algae. Most sea slugs eat plants and other sea slugs, whereas this clade’s diet consists of pretty much only algae. Through the magic of evolution, they gained the ability to steal chloroplasts from their food (this is called kleptoplasty). The way this works is quite similar to how aeolid nudibranchs use nematocysts. As the sacoglossan consumes algae, its body preserves the chloroplasts and stuffs them into its own cells.

“But won’t the chloroplasts die or something?” you may ask. And yes, the chloroplasts wouldn’t normally be able to mend themselves in a sea slug because plant cells produce specific proteins meant to heal their organelles. Through some freaky science stuff, sacoglossans have managed to prolong the lifetime of their stolen chloroplasts. This means that once they eat, they’ll be able to photosynthesize for months before needing another meal. And yes, you read that right. They fucking photosynthesize. When you wonder why scientists don’t just say plants photosynthesize and animals eat, remember it’s because of organisms like this who go out of their way to destroy all semblance of reason.

Due to their plant-like behavior, most sacoglossans have evolved to not only steal chloroplasts, but also to produce chlorophyll, leading to a green coloration. What’s more is that a number of these photosynthesizing angels look like plants or leaves.

The particular species displayed above is called a sea sheep or leaf sea slug. As you may be able to tell, they look a bit like succulents. Of course, not ALL sacoglossans photosynthesize. Only the cool ones do, the sea sheep being the ringleader of the Cool Sea Slug Gang.

Sadly, that’s all for the sacoglossans, and next time I’ll be talking about… sea hares.

Nonconforming Nudibranchs

Ah yes, the beautiful, vibrant, and deadly nudibranchs. These sea slugs belong to the clade Nudibranchia and are often divided into two sub-groups: dorid and aeolid nudibranchs. Before we get into all that, you do not pronounce nudibranch like “nudi-branch”. It’s pronounced more like “nudi-brenk” because why not.

Moving on, the first subgroup we’ll be covering is the dorid nudibranch infraorder (again, a taxonomical term). These bad boys have a branchial plume, AKA: a bunch of gills circling their anus. Yes, they do in fact breathe around their assholes, much like American politicians. Dorid nudibranchs are usually a more pastel color than aeolids because evolution. The lovely sea bunny belongs to this subgroup! That concludes the dorid segment, time to talk about the better sea slugs.

Aeolid nudibranchs are your neon sea slugs. Instead of a branchial plume, they’ve got cerata (singular is ceras). Cerata are pretty much jellyfish-like tentacles that store nematocysts. What are nematocysts? Nematocysts are stinging cells that are produced by jellyfish and a few other organisms (like hydroids). Aeolid sea slugs don’t produce these naturally, so instead, they steal them. Mature nematocysts explode on contact, but immature ones don’t, and are like buds. An aeolid’s cerata are all connected to its digestive system, allowing immature nematocysts to be carried into the tips of the cerata, into cnidosacs, where they will then mature. Gosh there’s a lot of vocabulary that needs defining. Cnidosacs are sacs at the tip of cerata that hold nematocysts and discharge them as a defense. This action is involuntary, so an aeolid can’t release its nematocysts whenever, they are only discharged as part of the organism’s fight or flight response. Aeolids also tend to have the brightest coloring out of all the sea slugs due to aposematism (their color is a warning to potential predators).

Above is the Spanish shawl sea slug, a species of aeolid nudibranch. Also, the coloring is in fact accurate, they are really that bright and colorful. The orange spine-like features are its cerata, and the orange feather-like two features are rhinophores. In this species, the oral tentacles are very pronounced.

Next up in the series is my favorite sea slug clade: sacoglossa.