Melibe nudibranch

A Melibe nudibranch is filtering for crustaceans with its unique hood. Image taken at the Monterey Bay Aquarium.


Yet another sea slug! I just can’t get away from them-I’m hooked! And who can blame me; this groups of animals has it all. Such a thorough example of adaptation at its finest can never fail to intrigue scientists or enthusiasts like myself.

Take this sea slug for example. First of all, those flat, paddle-like branches coming off of its body are called cerata. Sea slug cerata can have many functions, including gas exchange, color changing for camouflage, holding the stolen nematocysts to sting predators (See my first sea slug post for more information) and in some cases they contain part of the digestive tract. Comparing the cerata of different groups of sea slugs has been said to be similar to comparing the wing of a bird to the wing of a bat-they are that diverse in function and appearance. Anyway, if a predator grabs this sea slug’s cerata, it can detach the appendage from its body to get away. It will actually pull in its large “hood” to reduce drag and swim away. And later on, it will simply regrow its cerata. Regeneration. Now that’s part defense, part super power.

Not that the sea slug has to worry about many predators. The only animals it really has to worry about are kelp crabs. That’s because kelp crabs aren’t bothered by another defense of theirs-a toxic secretion that makes these nudibranchs smell like watermelon. Mmmmmmm….poisonous watermelon.

This genus of sea slugs are also unique because of their “hood,” the big, roundish, tentacle covered part of its head. Most sea slugs eat using a radula, which is like a scraping tooth. This sea slug however…well, look:

It uses its oral hood to filter small crustaceans out of the water. The hood is surrounded by sensory tentacles that help it to grab small food and pull it in toward its mouth. It’s pretty weird, but also beautiful and mesmerizing. And even though this looks really similar to a jellyfish, this animal is more closely related to an octopus than to a jellyfish.

I guess the last thing I want to show is this sea slug’s eggs. If you remember from the first post, I mentioned that sea slugs lay their eggs in beautiful ribbons, so here are some more see slug eggs attached to a kelp leaf:


sea slug eggs

Sea slug eggs attached under a kelp leaf. Image taken at the Monterey Bay Aquarium.


And there you have it! Yet another unique, amazing, beautiful sea slug.