Rare Sea Cucumber Found on Avalon, California Survey

By Reef Check California’s Southern California Regional Manager Colleen Wisniewski

It’s always exciting when you encounter a different species on a dive, especially after many dives in the same region. Such was the case on November 7th while we were performing our fall Reef Check California (RCCA) survey at the Avalon Dive Park on Catalina Island. I had just entered the water for my second dive with my buddy George and we were swimming over to our assigned transect area. I looked at the rocks below me and saw a large sea cucumber. I kept swimming for a few seconds when it finally hit me – “that’s not our usual warty sea cucumber!” I went back and took a closer look and was a bit puzzled. To my knowledge, I’d never seen this species before so I snapped a few quick photos to see if I could identify it later. It was much longer than our warty sea cucumbers (approximately 14 inches) and the coloring was a bit different, as well. 

Once back at the office, after a bit of research, we determined it was Holothuria zacae, a tropical/sub-tropical sea cucumber usually found along the coast of Ecuador, the Galapagos and Mexico. Its extreme northernmost range has been listed as Ship Rock at the west end of Catalina Island, just a few miles north of where we were diving. Needless to say, I was a bit excited! Not many California divers run across this species on their dives, so I felt pretty lucky. I’m reminded once again why RCCA is so interesting – aside from monitoring our indicator species, we can track rarely seen species and potentially notice trends in their ranges. I look forward to hopefully seeing some other rare species on survey dives in 2010!