NOWRAMP 2002

Name that shrimp!
Written by Mark Heckman, Educator, Waikiki Aquarium/ University of Hawai'i - Manoa

There is a great joy in discovery. We all feel it. Whether it is the discovery of a new idea, a new invention, or a new organism, humans are always in quest of the new and unknown. In biology, the discovery of a new species (1) is one such event. A scientist that identifies a new type of animal not only gets to name it, but gets their name listed with it as well. Thus the Blackspot Sergeant Major fish's scientific name is Abudefduf soridus (Forsskal, 1775). This fish was described ("discovered") by Forsskal in 1775 and he had the honor to name it (Journal: Heading Out).

But most major groups of fish and other vertebrates have largely been discovered at this point in history. This leaves, at first glance, little for the current and future generations to do. But wait; is the world really all about the vertebrates? Those animals that possess a backbone (a bony sheath of vertebrae) and most resemble us? Perhaps not, the vertebrate line includes only five percent of the animal life on Earth. Many of the most wondrous animals on this planet are loosely termed the "invertebrates". These are the animals without backbones, the animals that are "not us", the animals that are perhaps the most interesting and beautiful of all.

Even better for current and future discoverers and biologists, the "invertebrates" are tremendously understudied, unnamed and unknown. Here then is today's tale - of a simple invertebrate, a shrimp, that through the circuitous path that science often takes, may yet be a new species just "discovered".

Shrimps are part of the group Arthropoda (arthro, from the Greek = joint and pod = foot or jointed foot animals). This impressively successful group has an external skeleton that is articulated (jointed). This allows these armored creatures to use leverage across the joints to hoist themselves up and go into virtually all environments in the world (2). Arthropods comprise over eighty five percent of all known animal species, with many more yet to be described.

In 1999, a young dive master and marine photographer, Keoki Stender, heard from friends at the University of Hawai`i about a job running a dive operation at remote Midway Atoll National Wildlife Refuge. He and his wife had wanted to vacation on Midway, but the cost was too much. Here was a chance to spend months on Midway and get paid for it as well - low pay and hard work, but pay nonetheless. Keoki and Yuko took the job and began photographing the rare and unusual marine life they encountered.

The shrimps of interest to this story were not initially one of those animals. Part of the genus Rhynchocinetes (rhine ko sin e teas), these shrimp hide during the day and only come out at night when they are safe from marauding predatory fish. Home aquarists sometimes call them dancing shrimps for the delicate movements of their legs. Like many of their secretive kin, they can be spectacularly colored and patterned - elegant designs that few humans will ever see.

Now this particular population of Rhynchocinetes shrimp at Midway Atoll was not found at the beautiful dive sites well visited by the local SCUBA crowd. They were found in an area of desolate-looking pocked brown reef surrounded by sand. Not an area that divers or snorkelers would normally bother with.

Enter a bit of chance; some of this reef was just offshore the one open beach at Midway. During a day off, a well-known dive operator from Kona, Hawai'i noticed an unusual fish on this patch of reef while snorkeling. She asked Keoki to go out and identify the fish (those charismatic vertebrates get all the attention). The fish turned out to be reasonably common. Keoki identified it at a glance, and then happened to look beneath the fish in the urchin-filled holes. Small elegantly ornamented shrimp filled the holes as well. He took a photo.

The shrimp were not ones Keoki knew, so he posted the picture on his website and waited. About this same time, a science librarian and marine photographer (3) on Oahu, Hawai`i, had just finished a book on local marine invertebrates (4). The image came to his attention, he didn't recognize it, so he sent it on to a world expert on crustaceans (including shrimp), Junji Okuno in Japan. Junji also didn't recognize the beautiful little specimens, though they looked close to a species found in Japan. He wrote to Keoki expressing a wish for more photos and a specimen. The shrimp proved elusive and very difficult to catch.

This was in 1999. The shrimp continued their existence, moving about their tiny bits of drab reef flat, surrounded by white sand and turquoise water, blissfully unaware of human interest. Three years passed by.

Keoki now works for a ship called the Rapture, which was contracted to take a group of scientists through the Northwestern Hawaiian Islands (NOWRAMP 2002 Expedition). The Expedition stopped at Midway and Keoki brought the shrimp topic to the attention of the invertebrate specialist Dr. Dwayne Minton. Intrigued, Dwayne sorted through his gear and dropped a shrimp trap on the tiny bit of reef. Things looked good for the science, the shrimps were about to be formally "discovered" (it is doubtful that the shrimp cared, not a large mental capacity in a small shrimp; but they do what they do very well).

Unfortunately when Keoki went to retrieve the trap the next evening, winds came up and it became impossible to find the trap. The Rapture was due to leave. It could be years again before another try would be made. Score another point for the shrimp.

Then chance intervened yet again, as a crew member of an entirely different ship, the deep sea exploration ship the KOK fell ill. They steamed for Midway and the only doctor within hundreds of miles. A doctor that the Rapture brought along (diving expeditions can be dangerous). Dr. Robert Overlock, a veteran of dive medicine and expeditions, waited patiently for the KOK. If things went well, the Rapture would still be able to leave on schedule late that night. But one of the engines failed on the KOK; they fell behind schedule and the Rapture had to stay on Midway another day. It was time to go snorkeling.

I had snorkeled this tiny patch of reef several times. Now Andy Collins and I went out to find the trap. There it was with a tiny, beautiful shrimp inside. Only one had ventured out and into the trap - fair enough. Science no longer needs to collect numerous specimens to verify a holotype (true type), two will do, one in a pinch. No need to disturb the population, always take less than the predatory fish do. And undoubtedly there are many of these little shrimp spread out among the various small scoured and eroded reef flats on Midway and possibly other Northwestern Hawaiian Islands.

We are still just learning to look. We will take just our one, the one that had the poor luck to venture into the trap (no Darwinian jokes here or talk of the population giving one to the volcano). Junji Okuno will get his pictures and specimen, and Keoki will find out if he has a new species - a species that, through a very chancy and circuitous path has involved at least nine people so far. Perhaps it should be named Rhynchocinetes multipersonatus.

References: Dr. Dwayne Minton, Keoki Stender and Hoover, John P., 1998. Hawai`i's Sea Creatures, A Guide to Hawai`i's Marine Invertebrates, Mutual Publishing, Honolulu, HI, Randall, John E., 1998, Shore Fishes of Hawai`i, University of Hawai`i Press, Honolulu, HI.

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(1) In order to converse, talk, or (that favorite of scientists) have a spirited debate and discussion about an organism, biologists from countries all over the world have to agree on a name. To do this, they use scientific nomenclature, a system standardized throughout the world. A species is a group of animals that can easily reproduce with each other, resulting in fertile offspring that can create more of their own kind.

Thus the scientific name of the Blackspot seargent is Abudefduf soridus. The genus is Abudefduf, the species is sordidus. There are other similar fish, such as the Hawaiian sergeant Abudefduf abdominalis and the Indo-Pacific sergeant Abudefduf vaigiensis. They are all closely related and may even form the occasional hybrid, but normally they will not interbreed.

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(2) Look around you. Do you see any seastars roaming across the floor? Most likely not, ditto for squids, worms, or sea jellies (if you do, one wonders about where you live). Yet the arthropods are there, for this group includes the insects, spiders, centipedes and mites as well as crabs, hermit crabs, lobsters, shrimps, mantis shrimps, skeleton shrimps, and myriad more arthropod types. The external skeleton offers protection from desiccation (drying) and attenuation of fluids (from intrusion of fresh or salt waters into the body fluids if the animal is immersed in water) as well as protection from a myriad of other environmental and biological threats. Arthropods are found in the deepest ocean trenches, crawling slowly across ice flows in glacial regions, and floating thousands of feet up in the atmosphere.

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(3) Marine photography is a very expensive hobby and profession. Think about the cost of a good camera, triple that for an underwater housing. Double that again for the underwater lights. Add in a thousand or two for the SCUBA gear, then flood the camera and start over (salt water is a very hostile environment for sensitive gear). After the gear is put together, add in every available extra hour for diving and don't quit your day job - making a living solely at marine photography is a tough business. There are probably less that 50 full time professional marine photographers in the entire world.

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(4) Hoover, John P., 1998. Hawai`i's Sea Creatures, A Guide to Hawai`i's Marine Invertebrates, Mutual Publishing, Honolulu, HI

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