The unusual case of the salamanders living an aquatic life

Science · Published 8 October 2026 Swipe more like this →

In short: While most Eastern Tiger Salamanders live on land, a population in a Wisconsin reservoir has defied their biology. These adults have retained larval features like feathery gills and tail fins to thrive underwater. Scientists are now racing to study these unusual creatures before their man-made habitat is eventually drained.

In a six-million-gallon concrete reservoir located at the decommissioned Badger Army Ammunition Plant in Wisconsin, a biological anomaly is unfolding. While the Eastern Tiger Salamander is typically a land-dwelling species, a significant population has adapted to a fully aquatic existence. These individuals possess wide jaws, tail fins, and feathery gills—characteristics usually reserved for their larval stages. This deviation from their standard life cycle is a striking departure from the typical amphibian pattern, where species like frogs and toads generally inhabit land for most of their adult lives.

The discovery of this phenomenon dates back to 1993, when herpetologist Gary Casper of the University of Milwaukee identified the animals during an Army survey. At the time, researchers were unaware of how uncommon such larval characteristics were in adult Eastern Tiger Salamanders. Today, ecologists like Mike Mossman of the Wisconsin Department of Natural Resources estimate that more than a thousand of these salamanders may inhabit the reservoir. The population's presence in this specific location is a mystery, as ecologists believe they may have occupied the site for several decades.

The habitat itself is a remnant of a World War II-era factory, a site currently being dismantled and contaminated by metals, solvents, and explosives waste. While the reservoir appears unremarkable from the surface, it serves as a vital nursery where dozens of eggs can be found attached to buoy ropes in gelatinous sacs. However, the future of this population is uncertain; as the plant is decommissioned and the landscape is cleared, scientists are racing to study the species and potentially relocate them before the reservoir is drained. The surrounding area is undergoing a massive transformation, as heavy machinery and trucks move debris like broken concrete and metal rods to restore the local prairie. This intense demolition work makes the preservation of the reservoir's inhabitants even more urgent.

General information, not professional advice. Spotted an error? Flag the card or see corrections and complaints.

Intellect Plus is a visual educational discovery platform for exploring fascinating facts and ideas. Brain Food, Not Brain Rot. What is Intellect Plus?

Related

• The elusive spotted salamander spends most of its life hidden beneath the forest floor
• The world's most successful salamanders breathe entirely through their own moist skin
• Lizard-shaped amphibians that can regrow whole limbs
• The Japanese giant salamander is a long-lived, nocturnal predator that breathes through its skin.
• Why ancient legends mistakenly believed salamanders could survive inside of a fire
• Why do humans rub their faces together?
• Why does the rat's tail plant grow strange stems?
• Are humans uniquely built for the long-distance grind?
• How did the universe transition from inanimate matter to conscious experience?
• The surprising discovery that alligators can regrow their tails
• Ancient DNA from Greenland reveals a forest where an Arctic desert now sits
• Why do some people sneeze when they step into bright sunlight?

More in Evolutionary biology · More in Science · Latest · A–Z · All topics