Dive Dry with Dr. Bill

#276: Rainbow Star

Geographical isolation can be a very difficult thing for marine critters... and humans! There are times I feel I'm one of the cast members on the TV show "Lost," isolated from much of the rest of the world. Of course sometimes that's a very good thing, but it sure can affect one's "love life." Of course I can always cross the Channel on the Catalina Express (assuming I've sold a DVD recently to pay for the ticket), and I'm fortunate to have a number of dive friends I can stay with "over there." Some of our marine critters aren't so lucky, especially the ones which have very limited swimming... or crawling... ranges.

A while back I wrote about the lonely thornback ray I saw off Sea Fan Grotto. It was the only thornback ray I've ever seen in Catalina waters over the past 38 years, although they are fairly common on the mainland. It was a male, and that made me wonder if there were any female thornback ray within courting distance. At least the ray could swim a bit to try to locate a potential mate.

On a dive last summer at Little Farnsworth off the Edison plant, I encountered another critter I only remember seeing once in our waters... the rainbow starfish. I was just reminded of that sighting since I'm working on another new DVD on the echinoderms of southern California... starfish, sea urchins and their spiny skinned relatives. This species is also known as the red banded, red-and-white, painted or long rayed starfish. With so many names, the poor critter may have some identity confusion.

The rainbow star is a colorful starfish (or sea star if you want to be politically correct) with prominent sharp spines on its arms. It varies from a rose-pink mottled with gray to a reddish color mottled with yellow. The spines are whitish or sometimes lilac in color. Since there are no true blues or greens, it doesn't have the full spectrum of the rainbow, but who is counting wavelengths? They have long arms and a total diameter variously reported at 15 to 24 inches.

This starfish is at its southernmost range since it is known from Yakutat Bay, Alaska, to southern California. The primary field guide to invertebrates says it is only found down to Santa Rosa Island, which could make my sighting an extension of its known range. The rainbow star is found on rocky and soft bottoms, and the one I saw was on top of one of the submerged rocky pinnacles at this deep dive site. They are uncommon in intertidal waters further north, and may range down to depths of 800 feet

This starfish, like many of its relatives, feeds largely on mollusc. Clams are a favorite, and they are known to dig them out of soft bottom habitats using their arms and tube feet. They will also munch away on snails including limpets, scallops, chitons, crabs, barnacles, brachiopods and tunicates. Now I'm a fan of molluscs and crabs myself, and even tried limpet and barnacle stew on a survival hike to the other side of the island with my students at Toyon. Unbeknownst to me, they stopped for their "survival" meal at the Airport-in-the-Sky and failed the exercise when I found out! However, I'll draw the line at brachiopods and tunicates making me a picky eater.

I'm still puzzled as to the isolation this poor echinoderm must experience. Perhaps it arrived here as a larval form created by parents on Santa Rosa Island after drifting in the plankton for several weeks, and finally settled on Little Farnsworth to begin its lonely existence. All munching and no mating satisfies the need for individual survival but does little for the continuation of the species! How would you like to be the only human stranded on the island? You can bet the Catalina Express wouldn't be running much of a schedule for just one resident!

© 2008 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 49, 10:00 AM and 5:00 PM weekdays and on Charter Communications Cable channel 33 at 7:30 PM on Tuesdays in the Riverside/Norco area. Please help me climb out of self-imposed poverty... buy my "Munching and Mating in the Macrocystis," "Great White Sharks of Guadalupe," "Calimari Concupiscence: Mating Squid, " "Playful Pinnipeds: California Sea Lions," "Belize It or Not: Western Caribbean Invertebrates, Fish and Turtles," "Gentle Giants: Giant Sea Bass," "Common Fish and Invertebrates of the Sea of Cortez" or the new "Sharks and Rays of Southern California" DVD's. Yes, take Dr. Bill home with you... we'll both be glad you did!

Images of the rainbow star at Little Farnsworth.

This document maintained by Dr. Bill Bushing.
Material and images © 2008 Star Thrower Educational Multimedia