News about Nudibranchs
Nudibranchs belong to a group of soft-bodied mollusks called gastropods. Unlike many gastropods, they don’t have shells. The name “nudibranch” means “naked gill,” which refers to the frilly, gill-like appendages often visible on their backs. These “gills” are not just decorative; they’re for dissolved oxygen exchange (aka how they breathe) Nudibranchs come in a variety of forms, from smooth, flat varieties to those with spiky protrusions that help them blend into coral or mimic other sea creatures. Around Capers Island, we have found nudibranchs living in hydroids that grow on our crab traps! We have also seen one swimming around the marina dock before.
Nudibranch found on a crab trap.
Despite their delicate appearance, nudibranchs are far from defenseless. Their vivid colors often serve as a warning to potential predators that they may be toxic or distasteful. Some nudibranchs have even evolved the ability to absorb toxins from the prey they eat—like sponges or anemones—and store them in their bodies as a form of chemical defense. Others take things a step further by “borrowing” the stinging cells from jellyfish and incorporating them into their own tissues, making them particularly dangerous to would-be predators.
Zoomed in nudibranch!
Though they are a type of sea slug, not all sea slugs are nudibranchs. Sort of like all squares are rectangles but not all rectangles are squares. Stay with us!!! Sea slug is a general term for a marine shell-less or almost shell-less invertebrate. The further down the taxonomic branches you dive, the further divided by characteristics organisms are until you reach their unique species. Nudibranchs exposed gills are different than sea slugs who typically have a mantle cavity where oxygen exchange occurs.
If you’d like to read more on nudibranchs OR sea slugs we found some fun science blogs and resources to check out!
https://thetidepooler.com/2023/04/22/sea-slugs-vs-nudibranchs-whats-the-difference/
https://themarinedetective.com/category/marine-invertebrates/sea-slugs-nudibranchs/