The Well-Dressed Nudibranch

One of my favorite things to come across when I am SCUBA diving are the lovely little Nudibranchs (pronounced "nooda-bronk")! I would see them a lot when I was diving in San Diego, which was great because it would be this bright color on the rocks or crawling across the seafloor, which doesn't have the colors the tropics have. Nudibranchs are most diverse in tropical waters, although they can be found in oceans all over the world. So far, over 3000 species have been discovered and more are being found everyday!! Some divers refer to them as the "butterflies of the sea". They have been found in shallow tide pools and all the way down to 6,500 feet.

Nudibranchs are in the class Gastropoda and the phyllum Molluska and are a shell-less species kin to the sea slugs. That word probably doesn't paint a pretty picture in your head, but some of these nudibrachs have the most amazing colors and 'costumes'! Take the beautiful Spanish Shawl, Flabellinopsis iodinea, https://www.inaturalist.org/guide_taxa/2810 , that looks like it's dancing as it is slowly moving along with its purple, scarlet, and orange color pattern. This is one I

that I loved to see while SCUBA diving in San Diego. I do want to mention for the record, all nudibranchs are sea slugs, but not all sea slugs are nudibranchs (maybe this means I need to write an article about sea slugs)!

Not all nudibranchs have beautiful colors, though. Some are actually camouflaged to match their surroundings so it is easy to SCUBA right past them and never notice them. These soft-bodied carnivores use a band of curved teeth, call radula, to scrape off and tear food particles from coral sponges, sea anemones, eggs, hydroids, and even other slugs. The California aglaja, Navanax inermis, is one I have seen feeding on another sea slug while SCUBA diving in Mission Bay in San Diego. They are voracious predators and use chemoreceptors to track the slime trail of its prey.

Are you curious about nudibranch breeding habits? Well, of course you are! They are hermaphrodites and have both types of organs, probably so they can be opportunistic and breed with any adult that happens to crawl by. Cool fact: they can leave their penis inside their mate if they want (better ensures the chances of reproduction) and they can re-grow it in about 24 hours! Handy feature to have. If the breeding is successful they lay their eggs and they come out looking like these incredible 'ribbons', which are attached to rocks or something stable. The ones I have seen underwater are beautiful colors, too. The number of eggs they lay varies and their is one species that only lays one egg, while there is another species that lays 25 million! When the eggs hatch, the little 'noodies' hatch into free-swimming larvae (with shells that they shed later) and eventually end up on the seafloor like their parents.

Nudibranchs have eyes, but they cannot see very well, which is a shame because they can't even see how beautiful they are (or their mate is)! They use their rhinophores, located on top of their head and their oral tentacles located near the mouth to sense their surroundings. These critters have such amazing features that I will not touch on for this article, but scientists study them because they have a novel or rare chemical compound that has anti-microbial and anti-parasitic traits that could potentially help the fight against cancer (ThoughtCo.com).

I worry about the fate of these critters, as do I worry about the fate of all critters due to pollution, habitat destruction, and global warming. How many critters are we harming for our own materialistic desires? How much stuff do we really need? I know we are all guilty of doing our part in harming the environment, but let's try to make the smallest imprint we can. Remember when SCUBA diving or snorkeling to manage your buoyancy and not bump into the sea life or take from it. Let's do our part to protect critters, not just in the waters, but all over the earth! We can make a positive difference, too.