Who doesn’t love nudibranchs? These amazing little gastropods can be found in ocean environments all over the planet, they’re extremely photogenic, and they can be absolutely fascinating to watch. As nudis go, Melibe Leonina, the Lion’s Mane Nudibranch (also known as the Hooded Nudibranch,) takes the cake. Unlike so many of the world’s most studied nudibranchs, which hail from the Indo-Pacific region, this little marvel is a native of the west coast of North America. What makes this creature stand out from its contemporaries isn’t brilliant colors; instead, it is the animal’s ability to disguise itself as a nearly transparent jellyfish in order to attract and capture its prey – which often happens to be real jellies! Let’s take an up-close and personal look at this wonderfully weird little sea creature.
A Bouquet of Sea Slugs
Most sea creatures have a slightly salty or fishy odor when removed from the marine environment. When it comes to the Lion’s Mane Nudibranch, this old maxim couldn’t be any further from the truth. As these nudibranchs look very much like flowers when they hold themselves open, and as they have a fruity – floral scent when taken from the water, a group of Lion’s Mane Nudibranchs is fondly referred to as a bouquet. But the weirdness doesn’t stop there.
This fascinating little sea creature has a wide, expandable oral hood lined with tentacles that detect prey whenever the hood is open. While you might very well encounter Melibe Leonina crawling along the sandy seabed or lounging among eel grass and seaweed stands in shallow water, you’re just as likely to encounter it swimming or floating freely in the water column with its body extended in a graceful imitation of a jellyfish. At certain times it will attach itself to a strand of kelp or seaweed with its body extended, and during mating, you’ll find large aggregations of the nudibranchs, usually in areas where kelp is abundant. For jellyfish, copepods, ctenophores, and small mollusks that get too close, it’s game over. The nudibranch rapidly closes its body in a manner that’s reminiscent of a Venus fly trap; its tentacles intertwine, preventing the prey animal from escaping before it can be consumed.
The Lion’s Mane Nudibranch is small at just about 100mm long and 25 mm wide; when expanded, it is approximately 50mm wide. Its body is translucent, usually with a yellow to green tint, and it has between eight and twelve paddle-like tentacles that grow in pairs and that can be shed if grasped by a predator.
Like many other nudibranch species, Melibe Leonina has a lifespan totaling about one year. And like other nudibranchs, the Lion’s Mane Nudibranch is hermaphroditic. These nudibranchs practice reciprocal fertilization, then lay eggs in wide cream-colored ribbons that can be easily spotted as they contrast sharply with the dark green kelp fronds to which they are typically attached.
If you hope to encounter Lion’s Mane nudibranchs while diving, you’re in luck. They’re quite common from Alaska to Mexico’s Baja California, and they normally prefer fairly shallow water. So grab your camera and head to your favorite west coast dive site. The odds of capturing images of these captivating sea creatures are definitely in your favor.