“Think Like a Brittle Star”

By David Ginsburg

Originally published at ScientificAmerican.com

On a recent collecting excursion in Palau, I repeated the mantra “Think Like a Brittle Star” over and over as my colleague Jim Haw and I searched for a specimen (Ophiotylos leucus) that was last seen 76 years ago by Japanese scientists (cf. Murakami 1943). With the help of Pat and Lori Colin from the Coral Reef Research Foundation based in Koror, we poured over Japanese-era maps and aerial photographs trying to identify at least a general location in the intertidal zone from where we could start our search for these animals.

Aerial view of SW Nikko Bay, Palau (Koror State). Image courtesy of the Coral Reef Research Foundation.

Beginning in the 1920s, as part of the South Pacific Mandate, Japan began a large-scale effort to develop a range of natural resources available on these islands, which included phosphate and bauxite mining, oil exploration, as well as copra and sugar cane production. Natural science also played an important role in the mandate, and in 1934 the Palao Tropical Biological Station was established on Koror Island with a research mission to study coral reef biology and ecology (Abe 1937, Abe et al. 1937). Internationally recognized as the premier location in the Western Pacific for coral reef studies (Yonge 1940), basic research on Palau suddenly became complicated when Japan attacked Pearl Harbor on December 7, 1941.

Japan declares war on the United States. Image courtesy of the Honolulu Star-Bulletin archive.

Specimens collected by Japanese researchers at the Palao Tropical Biological Station were sent to their home institutions for further study and analysis. Results from these investigations were published in the appropriate scientific journals of the day (see Work Cited for examples). While that primary literature is still accessible today, the majority of voucher and type specimens were lost (most likely destroyed) during the war, including the brittle star Ophiotylos leucus, which was collected and described by Murakami and his colleagues in 1938.

While collections of Ophiotylos have been made since (from Hawaii and Japan, respectively), they are classified based on a suite of Palauan type specimens not seen since World War II. To add further intrigue to this story, the genetic relationship among different populations of Ophiotylos is unknown. Unlike other species of brittle stars, which haphazardly broadcast their gametes into the plankton, Ophiotylos broods its young (early stage juveniles remain close to the parent). How this species has found itself distributed across its current range is a mystery. Thus, the Palauan type specimen may serve as an important genetic link between individuals collected across the temperate and tropical waters of the Pacific.

Front cover of Palao Tropical Biological Station research journal (May 1937; Volume 1, Number 1).

My initial interest in this project was spurred by a conversation with my friend Gordon Hendler, curator of echinoderms at the Natural History Museum of Los Angeles. As Gordon’s specialty is the phylogeography and taxonomy of brittle stars, he was excited to learn that I was once again leading a group of USC undergraduates to Palau, and planned to stay a few extra days after the course was complete to follow up on a couple of research projects. From this meeting, we hatched a plan to track down Ophiotylos and reopen a marine science cold case, which has been a pet project of Gordon’s for some time. Although he could not join us on our trip, Gordon provided Jim and me with a stack of relevant research materials, maps, and the advice that our success in the field rests largely on our ability to “think like a brittle star.”

Given that the brittle star in question is roughly 2-3 cm in total length, lives somewhere amongst the high intertidal, sea grass-coral rubble habitat of Nikko Bay, and was last seen some 70 years ago, I figured I could use all the advice I could get on this project. We started our search for the mysterious Ophiotylos by snorkeling along an area of Nikko Bay known as Omode Channel. After our first day in the field, we turned up more than our share of brittle stars (as well as a fair number of cuts, stings, and irritations from brush-ups with coral, hydroids, and sponges). Unfortunately, Ophiotylos was not amongst them.

On our second day, however, we struck gold! After several hours of swimming or crawling in face-deep water, and having the depressing feeling that our efforts were no better than a wild goose chase, we spotted three individual Ophiotylos specimens amongst the benthos in as many minutes. After searching for more without further success, we eventually ended our excursion and headed back to the Coral Reef Research Foundation’s laboratory facility. As we were scheduled to return to Los Angeles the next day, three specimens would have to do. Interestingly, looking through Murakami’s article from 1943, the last collections of Ophiotylos from Palau were made on June 6, 1938 – nearly 76 years to the day of our recent discovery (June 5, 2012).

Ophiotylos leucus specimen collected from Omode Channel, Nikko Bay, Palau (Koror State). Photo by Jim Haw.

I can’t say our field techniques were elegant; one minute there was a cloud of sediment and muck and the next the little beast we were looking for was right under my nose. What I can say with absolute certainty is that the only thing on my mind leading up to that eureka moment of finding Ophiotylos were Gordon’s final last words of advice; the path to success is to think like a brittle star!

Work Cited:

Abe, N. (1937) Ecological Survey of Iwayama Bay, Palao. Palao Tropical Biological Station Studies. Vol. 1, No. 2

Abe, N., Eguchi, M., and F. Hiro (1937) Preliminary Survey of the coral reef of Iwayama Bay, Palao. Palao Tropical Biological Station Studies. Vol. 1, No. 1

Murakami, S. (1943) Report on the Ophiurans of Palao, Caroline Islands. Journal of the Department of Agriculture. Kyusyu Imperial University. Vol. 7, No. 4

Yonge, C.M. (1940) The Palao Tropical Biological Station. Nature 145, 16-17

Editor’s note: Scientific Research Diving at USC Dornsife is offered as part of an experiential summer program offered to undergraduate students of the USC Dana and David Dornsife College of Letters, Arts and Sciences. This course takes place on location at the USC Wrigley Marine Science Center on Catalina Island and throughout Micronesia. Students investigate important environmental issues such as ecologically sustainable development, fisheries management, protected-area planning and assessment, and human health issues. During the course of the program, the student team will dive and collect data to support conservation and management strategies to protect the fragile coral reefs of Guam and Palau in Micronesia.

Instructors for the course include Jim Haw, Director of the Environmental Studies Program in USC Dornsife, Assistant Professor of Environmental Studies David Ginsburg, SCUBA instructor and volunteer in the USC Scientific Diving Program Tom Carr and USC Dive Safety Officer Gerry Smith of the USC Wrigley Institute for Environmental Studies.

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