Range: Marine waters worldwide Habitat: Varies by species Size: 0.25-12 inches (0.635-30.48cm) long Diet: Algae,coral, sponges, and more Threats: Sea turtles, fish such as parrotfish, sea stars, and nudibranchs Life span: About one year

Transcript:

Today on Animal Fact Files we’re talking about sea slugs. Squish the sub button to keep up with new episodes. Today’s request was from Peques; let’s see what there is to learn! Just to be clear, we’re going to specifically discuss nudis today. Erm… no… nudis as in nudibranchs. As yes, I know it looks like nudibranch, but the Google overlords have confirmed it.

Nudibranchs are like the shell-less snails of the sea, at least in their adult form. In their larval stage, nudibranchs have shells, but these are quickly lost as the nudi undergoes metamorphosis. There are more than 3,000 species of these sea slugs living in just about all the world’s oceans with more being discovered each year, so, of course, there are differences in how they develop, but, generally speaking, nudibranchs hatch from eggs as larvae and then after a few weeks they metamorphose into adults.

As adults, they seek each other out for reproductive purposes; as long as an individual can find another individual of their species, they’re good to go because nudibranchs have both male and female reproductive organs. They’ll mate, each fertilizing the eggs of the other, and then be on their way sometimes leaving behind their reproductive organs in the process. On average, nudibranchs live to be about a year old, and they don’t really fair well in captivity - much to the dismay of aquaculturists, I’m sure, because these slugs are freaking beautiful.

Most people don’t think of slugs as adorable, but nudibranchs are an exception. These sea slugs come in all the colors under the sun and they have funny little appendages that just add to their intrigue. As cute as they are, however, they aren’t quite so cuddly. Apart from being so small that on average they could fit on the length of your finger, they’re built to avoid confrontation with predators.

Some species are able to ingest the stinging cells of their cnidarian prey and then stow those stingers away for their own later use, and others can utilize the toxic chemicals released from the sponges they consume to make their own bodies unpalatable to predators, but even these tactics don’t stop all predators. Nudibranchs are eaten by sea turtles, fish such as parrotfish, sea stars, and even each other. So, while it’s not advisable to touch them, we still highly recommend enjoying their amazing appearance.

Depending on the species of nudibranch, they may have more or less pokey things sticking out of them. The general purpose of these floofs is to help with breathing and defense. The two floofy antae-like structures on their heads are called rhinophores and these help nudibranchs sense the environment around them. It’s a sad truth that nudibranch eyes are pretty underdeveloped, so they never really get the chance to appreciate just how fabulous they look. But we can! Let’s take a moment to appreciate our own awesome eyeballs and get to know a few specific nudibranch species.

There’s the blue dragon who swims along the surface of the ocean belly up and almost exclusively eats the organisms known as the Portuguese man of war; there’s also the eastern emerald elysia who appears bright green because it can literally photosynthesize, a tactic usually reserved for plants; and there’s these guys who don’t have a common name, are parasites to jellyfish, swim upright like a fish, and biolumines. That’s just a tenth of a percent of what awesomeness exists within this order of sea slugs.

For more facts on sea slugs, check out the links in the description. If you enjoyed this video, be sure to give a thumbs up, and thank you for watching Animal Fact Files!