Honolulu Star-Advertiser © Susan Scott
September 21, 2009
Last week while walking Lanikai Beach, I saw a bright orange-and-yellow candy wrapper tumbling in the shore break. Wading in a foot or two, I picked it up.
Oh, if only all marine trash could be this good. I’d found a Spanish dancer.
Spanish dancers, found worldwide, are the largest sea slugs in the world. They grow to 12 inches long, but Hawaii’s are usually smaller. When I picked this one up, it spread out flat and covered my hand.
When it comes to sea slugs, I prefer their scientific name because the word “slug” doesn’t do them justice, and the Latin term is easy. These snails-without shells are called nudibranchs (NOODY-branks), meaning naked gills. Since the whole body is naked, shellwise, I often shorten the name to nudies.
Nudibranchs are orchids of the ocean. One local author likens them to butterflies because of their striking colors and patterns. Another writes that nudibranchs exhibit an exuberance unparalleled in the animal kingdom. The names of some Hawaii species say it all: snow goddess, jolly green giant, imperial, polka-dot, rosy, etc.
Of the world’s approximately 2,000 species of snails without shells (nudibranchs are one of five groups), Hawaii hosts about 150 with names. Far more are known to grace our reefs but don’t yet have scientific or common names.
The shapes of these snails vary widely, some being long, narrow and frilly; some round, flat and bumpy; and most everything in between. Most have stunning colors in unique patterns, and in animals that usually means they’re advertising something. In nudies the message is: Don’t eat me. I taste bad and might poison you, too.
Nudibranchs don’t make their own noxious substances to repel predators. They recycle ready-made weapons from the food they eat.
It’s easy to imagine how nudies might do this in, say, sponges, because some sponges have glass spikes in their bodies and toxic slime on their surfaces. The kind of nudibranch that eats those sponges — the Spanish dancer, for one — stores these spears and poisons inside its own tissues.
Recycling of other nudibranch favorites, such as hydroids, coral and Portuguese man-of-war, is trickier. These related creatures all carry their poisons in tiny sacs containing a harpoon delivery system. When the sacs, called nematocysts, are touched even the slightest, the harpoon pops out, sticks into whatever touched it and injects toxin.
We Hawaii swimmers know all about these painful shots when we accidentally scrape a coral head or run into a man-of-war. Fortunately, the sometimes miserable sting is not life-threatening.
How nudibranchs manage to catch, digest and store nematocysts for their own defense, without setting them off, is a miracle of nature.
The well-named Spanish dancer is another miracle of nature. This red, orange and yellow animal swims through the water by bending its body back and forth while flaring out its flexible edges, or “skirts.” You can watch this incredible dance (to salsa music!) at www.youtube.com/watch?v=SBlB1-EabgI.
When I waded out to release my Spanish dancer, sadly, its salsa days were over. But this nudie’s death was timely. By washing ashore at this writer’s feet, it became an ambassador for its kind. The spirit of the dancing red nudie lives on.