Freshwater
Adapted to inland rivers, creeks, and lakes, pumping out excess water through specialized kidney filtration.
Surinam Toad
The flat, leaf-like toad that carries its developing young inside honeycomb pockets on the mother's back.
Volta Electric Eel
The biological super-battery that hit 860 volts, the strongest electric discharge known from any living animal.
Water Flea
A mostly see-through pond crustacean whose 200-megabase genome holds at least 30,907 genes.
Wels Catfish
Europe's largest freshwater fish, and on one French river, a hunter that beaches itself to grab pigeons off a gravel island.
West Indian Manatee
A gentle sea cow whose dense bones may help keep it neutrally buoyant, and whose weak low-frequency hearing may be part of why boats keep hitting it.
Western Grebe
Tied with Clark's grebe as the largest animal known to run on water, sprinting across a lake in a courtship display called rushing.