First Cave-Dwelling Flatworm Discovered in Brazil

The first cave-dwelling flatworm was recently discovered in northeastern Brazil, adding this organism to the unique group of unpigmented and eyeless creatures that lurk in such deep, dark caves, new research describes.

As the first of its kind, this flatworm was assigned to a new genus and species of freshwater flatworm, and for the researchers credited with the discovery, it may also constitute an oceanic relic.

The study was published in the journal ZooKeys.

Freshwater flatworms, also called platyhelminths, are a group of invertebrates that, 80 percent of the time, are parasitic, according to Encyclopaedia Britannica. They are bilaterally symmetrical - meaning their left and right sides are identical - and lack specialized respiratory, skeletal, and circulatory systems.

They occur in a wide range of habitats, namely streams, lagoons and ponds, among others. Some species are also found in subterranean freshwater environments.

Brazil has more than 11,000 caves, the press release states, and yet their species diversity is largely unknown. Field work by Rodrigo Ferreira, from the University of Lavras, Brazil, in a karst area located in northeastern Brazil, has found the first obligate cave-dwelling flatworm in South America.

The new species, dubbed Hausera hauseri, is a typical cave-dwelling organism, unpigmented and eyeless. Most cave-dwelling organisms are both transparent and eyeless because, as goes for the Mexican tetra fish, another cave-dweller, eyes at least are another avenue for injury and infection, and the lack of light doesn't necessitate color.

Not only is the discovery of this flatworm unique, but so is the sampling area from which it was found - at least in comparison with other karst areas in Brazil. Most Brazilian limestone formations are located in inner portions of the country, which probably prevented marine groups from inhabiting these caves in the past. In contrast, this karst area is located near the ocean, and its limestone outcrops are at low altitude, which has allowed different invertebrates to colonize the caves during prior sea level rises. Thus, the new species may constitute an oceanic relict, as is the case of other cave-dwelling invertebrates found in this area, researchers say.