Manatees Might Carry Half a Million Microscopic Hitchhikers

Previous studies had linked nematodes to manatee skin. One of them described in 2011 an “exceptionally” long-tailed diplogastric nematode, Cutidiplogaster manati, which was found in skin lesions of West Indian manatees in an aquarium in Okinawa, Japan. This piqued the interest of these authors who hoped to learn more about C. manati. In 2013, they began collecting samples from Florida manatees at the Crystal River National Wildlife Refuge, and the project became Mr. Gonzalez’s master’s thesis.

The team likely found C. manati – and two other nematodes.

Mr Gonzalez, who worked with researchers who conducted an annual manatee health assessment, collected dead skin from the tails of seven mammals in 2018 and another seven in 2019. The collection process is akin to a human back scratcher, and the animals are quickly returned to the water, said Mr Gonzalez, to minimize stress.

The samples were examined under a microscope, then their DNA was extracted. The new nematodes had large teeth – perhaps for eating other nematodes or for “something tricky” like splitting open diatoms and consuming them, said Robin Giblin-Davis, a recently retired nematologist at the University of Florida and co-nematode author of the Study. The team speculates that C. manati and one of the others, a previously unidentified species they called “Long Tail,” might use their long tails to anchor themselves in the waves.

Although more work would be required to formally describe the species of the two new nematodes, “they could be said to be new species,” said Adler Dillman, an associate professor at the University of California at Riverside who was not involved in the study.

According to the study, the nematodes are specially suited to thrive in this decaying micro-landscape, where structures on the skin would be as tall for them as trees were for humans. All three manatee nematodes were found in all manatees sampled in 2018 and 2019, but no skin lesions were found. The authors concluded that the nematodes are unlikely to harm their hosts. Perhaps, they suggested, they are exchanged between manatees like human skin mites.

For now, the researchers hope to arouse more enthusiasm for nematodes and their gentle manatee hosts.

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