[Photo] Atretochoana eiselti is the largest lungless tetrapod and the only lungless caecilian. Photo by Matt Roper

A creature discovered by engineers building a dam in the Amazon is a type of caecilian, a limbless amphibian that resembles an earthworm or as some are noting, part of the male anatomy.

The animal was discovered while draining a portion of the Madeira River — a major tributary of the Amazon — for a controversial hydroelectric project. Six individuals were found according to biologist Julian Tupan, who identified the species as Atretochoana eiselti. Little else is known about the species, although it is thought to be aquatic and lacks lungs, breathing through its skin instead. Other individuals have been found near the mouth of the Amazon, more than 2,500 km away. Caecilians are typically predators, feeding on small fish, worms, and other aquatic invertebrates. They have poor eye-sight and navigate primarily though smell.

Atretochoana eiselti is the largest known caecilian, attaining a length of 75 cm (30 inches), or more than twice the size of the next-largest known species.

Atretochoana eiselti's population status is unknown, but the area where it was most recently discovered will soon be impacted by the Santo Antonio Dam near Porto Velho in Rondonia. Environmentalists have criticized the project, noting it will flood rainforest and require degazetting a section of national park. Brazil is currently in the midst of a dam-building spree in the Amazon, with 30 dams on tap for 2020. Ecologists warn the dam-building activity could affect fish migration and nutrient flows through the Amazon basin.