The image of the trail-weary naturalist hacking through dense thickets of tropical rainforest is the scene that most people would see as ripe for the discovery of rare species, new to the human eye. However, Dr. Janine Caira has described over 50 new species in an environment even less well-trekked - the interior of the ocean's sharks.
Caira is a parasitologist, a biologist who studies the many creatures that scrounge a living off host animals. Parasitologists are generalists by nature, familiar with broad classes of animals and their lifestyles.
"We have to know everything about the host and all the parasite groups...and the vertebrate host is just one of the hosts," said Caira.
Caira entered her line of work thanks to a summer job working on plant parasites taken at the advice of her high school gym teacher. She went on to get a master's degree in British Columbia based around her work with parasites of insects. After earning a PhD from the University of Nebraska, she came to UConn to establish her lab.
The Caira lab is constantly buzzing with activity, and the group is world-renowned for its work on cestodes, also known as the tapeworms. The cestodes include a large number of members which live in sharks and their relatives, the rays. Caira estimates that a typical shark species will have between one and four cestodes which parasitize it; a ray species may have up to a dozen.
Caira said that the reason for such diversity is a result of the long history that tapeworms, sharks and rays share.
"We think that they have been with their host for over 200 million years, and I think over that period of time, it's natural that you'll get [the emergence of new species]," she said.
According to Caira, tapeworms live almost exclusively in an organ known as the spiral intestine, a compact digestive organ that serves as a combination of the small and large intestines in mammals. The conditions within the spiral intestine vary across the different species of sharks and rays and provide different habitats for the cestodes which parasitize them.
To track down these elusive worms, Caira and her students go on collecting trips to distant places on the globe. Their most exhaustive searches take place in Baja, Mexico, Borneo in the South Pacific and Australia. They work with specialists on a variety of shark parasites, so that all the finds can be carefully analyzed and documented. Contacts with fishermen help them obtain the organs from sharks which are dissected to reveal the unique creatures within.
"We usually work with local fisherman if we can, because what we need is stuff that they don't want." said Caira. "The organs we need are the gut, the nose and the gills, and they just don't want those organs."
At the lab the team examines the tapeworms with microscopes. Their trained eye sorts them into different species based on the body parts they use to attach to the host and also the arrangement of their reproductive organs. After being cataloged, the specimens stay preserved on glass slides or in vials. An international network of researchers on shark parasites exists, and Caira frequently exchanges specimens with scientists in other universities to advance their research.
Due to their work, the tapeworms of some 400 species of sharks and rays have been described. These studies are critical in a time when rapidly failing fisheries predict a grim future for many shark species.
"That's why we're doing so much collecting now," Caira said. "If we can work with fishermen who are fishing legally now, we might as well, because things are going to change in the future."
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