Aquanaut Pam Cox Jutte

What is a Mantis Shrimp?

iving underwater in the Aquarius habitat saturates you--literally and figuratively--in the marine environment. Moored to the ocean floor four miles off the coast of Key Largo, Florida, forty-seven feet down, the Aquarius is the world's only underwater research facility. The scientists who live there, "aquanauts," acclimate their bodies to its fixed depth in what is known as "saturation diving," in which their tissues become saturated with dissolved gas. Once a diver is saturated, decompression--the time required to bring the diver back to surface pressure without inflicting the bends--is the same, regardless of the time spent underwater. As a result, Aquarius aquanauts can work underwater nearly nine hours a day.

Pamela Cox Jutte '93 was an Aquarius aquanaut last summer, taking part in a ten-day mission to study the ecology, behavior, and visual systems of stomatopod crustaceans--commonly known as mantis shrimp. Jutte, a research scientist with the South Carolina Department of Natural Resources, became involved with the project through colleagues in California. After earning her bachelor of science degree in biology at Duke, she completed a Ph.D. in 1997 at the University of California at Berkeley. Her dissertation research focused on the ecology, behavior, and visual systems of a type of mantis shrimp.

Roy Caldwell, Jutte's former adviser at Berkeley, is a world-renowned mantis shrimp expert. When he received funding to use the Aquarius habitat to research mantis shrimp, he approached Jutte to see if she was interested in collaborating. Although currently studying the environmental effects of human activities on marine invertebrates, she jumped at the chance for an Aquarius mission and to study mantis shrimp again. Scuba-certified since 1991, she frequently dives for her current research.

The Aquarius mission would look at several aspects of mantis shrimp biology. Jutte's fellow aquanauts included Mark Erdmann '92, the Marine Protected Areas adviser for the U.S. Agency for International Development's Natural Resource Management Project in Bunaken National Marine Park in north Sulawesi; Helen Fox, a graduate student at the University of California at Berkeley, studying coral regrowth after dynamite fishing; Alex Cheroske, a graduate student at the University of Maryland, Baltimore County, researching mantis shrimp vision; and Mike Hutchens and James Talacek, dive specialists with the National Undersea Research Center, who maintained and operated the Aquarius habitat during the mission. The surface team included Caldwell, the principal in-vestigator for the mission; Tom Cronin Ph.D. '79, a professor at the University of Maryland, Baltimore County; Karla Heidelberg, a research associate with the University of Maryland, College Park; and Nerina Holden, a strategic planning manager with the Scottish Environment Protection Agency.

The aquanauts and most of the surface team arrived in Key Largo about a week before the mission. Aquarius aquanauts are required to have logged at least 100 dives before they are eligible to descend to the lab, but because of the risks involved with saturation diving, intensive training is required for even these experienced divers. In normal diving, divers can return to the surface during an emergency. But surfacing is the main risk to saturated divers, since rapid ascension can cause a life-threatening case of the bends. Aquarius training involves five days of lectures on saturation diving techniques, safety, and habitat operation.

Sea life: aquanauts Jutte and her colleagues experience the wet world of crustacean research, sometimes as deep as 110 feet, from their "space capsule" habitat photos:courtesy University of Wisconsin-Madison

Two dives were completed each day near Aquarius, in part to familiarize divers with the nonstandard diving gear, safety drills, and to tour the habitat. Its quarters are tight, but include six bunks, a full bathroom, a galley, and viewing portals. Much of the space is taken up with laboratory equipment--video monitors, computers, and microscopes. Communications are sent by wireless telemetry to a surface buoy, then beamed to shore. Large canisters of oxygen and nitrogen provide the capsule's air, mixed at the same ratio as surface air.

After additional dives over the weekend to establish study sites, the aquanauts were ready to live underwater. Besides recording her scientific findings during the mission, Jutte kept a journal of her ten days beneath the waves, capturing her impressions of undersea life and the rewards and challenges of her research.

Day 1--July 16, 2001

This morning we hurry up and wait for our departure for the lab. When the time finally arrives, we aquanauts board the boat for a thirty-minute trip out to the Aquarius mooring site. It's hard to believe I won't be seeing the sun for the next ten days. We arrive above the Aquarius around 11:30. In addition to normal wetsuits, masks, and fins, our bulky aquanaut gear includes double tanks, a safety reel, a backup safety reel, a radio in a waterproof housing, and a pouch filled with a light, strobe, map, and various other safety gear. During our last minutes on the surface, my buddy Alex and I check each other's gear to confirm that no air is leaking from our scuba apparatus, and that there are no other equipment problems. We then descend to sixty-five feet, and begin our Aquarius mission.

We get right to work in the sandy areas surrounding the habitat, seeking two types of mantis shrimp, Nannosquilla and Bigelowena. We also spend part of our time examining the exterior of Aquarius. The habitat looks something like a space capsule. The actual living quarters are a long, school-bus-sized yellow cylinder perched about twenty feet above the seafloor on four sturdy legs. Periodically, as air is refreshed inside the habitat, a huge surge of bubbles escapes through the moon pool (an opening in the floor of the wet porch--our entrance to the ocean). On one side of the habitat, on the level of the living quarters, there is a white hexagonal structure called a gazebo. The gazebo is constantly replenished with air and serves as the location where aquanauts can meet and discuss research without entering the habitat. The gazebo has a separate air supply--should there be a problem with the habitat, we would escape to the gazebo and await rescue.

The habitat's sides are encrusted with all sorts of marine organisms, and a variety of fish use this as their permanent dinner buffet. There is also an omnipresent school of small, silvery baitfish. When you leave the wet porch to begin a dive, the school is so dense that you are enveloped in a cloud of pulsing silver. These fish also provide our entertainment at meal time--through the dining-room porthole, we see these bait schools being slowly depleted by the resident snook, barracuda, and grouper.

After spending about two hours in the water, Alex and I return to the habitat with the specimens we had collected. We take a few minutes to unpack. Each aquanaut's bunk has a small storage bin for clothes and toiletries. Each bunk is a little over six feet in length and about three feet wide. There are fresh sheets, a blanket, and a pillow on each bunk. I'm in one of the top bunks--with a little luck, I won't roll out of my bunk during the mission. Mark barely fits into his bunk, so I figure I could have it worse.

We complete another two-hour dive in the afternoon, mapping densities of stomatopods in areas near the habitat. Over dinner, we discuss the day's achievements, and develop our dive plan for the following day.

Aquanauts experience a wet world photos:courtesy University of Wisconsin-Madison

Day 2--July 17, 2001

Alex and I start our day testing a piece of equipment called a polarimeter, which measures polarized light in the waters surrounding Aquarius. This will give us a good idea of the type of light experienced by mantis shrimp living in the area. Tom Cronin has fine-tuned this equipment and the software it uses. Alex stays inside and runs the computer. I take the polarimeter on the deck outside the habitat and dive by myself using the "hookah" system, a breathing line tethered to the habitat. In normal diving, your buddy is your backup air supply should a problem occur. In hookah diving, a scuba tank on your back functions as your backup air supply. Through a combination of flashing-light signals on the polarimeter and quick swims to look inside the habitat through a porthole where Alex is working on the computer, we are able to work out all the bugs.

Alex and I return to the sandy bottom to complete transects around the habitat. We measure out fifty-meter transect lines on the seafloor and move along the line, centimeter by centimeter, counting and identifying the mantis shrimp burrows. We want to collect at least five transects at this location, and five at deeper sites to determine if there are differences in densities and species diversity with depth. Following the completion of these transects, we search for the burrow of a Lysiosquilla, a very large mantis shrimp that can grow to more than a foot long. These lie-in-wait predators belong to the "spearer" group of stomatopods, having front appendages with large spines that are used to impale fish and other prey.

We find several large burrows, and set up an underwater video camera with infrared lights above one of the burrows. Various cables are strung back to the habitat, and we are able to watch the large male Lysiosquilla twenty-four hours a day as he hunts for food for his mate, who is hidden beneath the sand. We hope to record his behavior for at least a day and then capture and remove the male. These animals form monogamous pairs, and you would normally never see a female; however, Roy Caldwell's previous work has shown that once the male is removed, the female often gets a new mate. By videotaping the animal, we can get a better understanding of how the female may let other males know she is available.

Upon returning to the habitat, I take a quick shower. The shower onboard the Aquarius is located in the wet porch, where you enter from the ocean. The tiny shower stall is separated from the rest of the room by a curtain and has hot and cold water. The water is stored in tanks outside the habitat and must be delivered from the shore, so we are encouraged to take very quick "navy" showers. On the first day, we were all given a chamois to get rid of most of the water, and a single towel for any additional drying.

During dinner, we work on our dive plan for the following day. Mark and Helen have begun marking individual Odontodactylus burrows and are learning that many of these animals seem to have multiple burrows. After dinner, I head back out on the hookah at "storage depth" to hunt for stomatopod larvae. Since we are living at forty-seven feet during this mission, any dives that do not go deeper than that are considered "storage depth," and do not count as an official dive. I ask the habitat technicians, Hutch and James, to turn off the exterior lights around the habitat. Using small dive lights that attract various larvae, I can look into the surrounding waters for the distinctive stomatopod larvae. I don't find stomatopods but see all sorts of amazing larval critters floating in the water. When I turn my light toward the bottom, large stingrays, almost four feet across, can be seen swimming by. When I turn my dive light off, the surrounding water is filled with a beautiful bioluminescence.

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