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A-Z-Animals
9 Animals That Can Live in Salt and Freshwater
By Jennifer Geer,
12 hours ago
The vast majority of water-dwelling animals are either adapted to live in saltwater or freshwater, not both. Some animals, such as oysters , can tolerate salinity changes to their usual environment for short periods. However, a small percentage of fish and animals have adapted to live in saltwater and freshwater. The rare animal that can survive in a wide range of salinities is known as euryhaline , while fish that move between saltwater and freshwater are diadromous . Read on for our list of nine animals that can live in salt and freshwater.
1. Beluga Whale
One of the smallest whale species, a male beluga whale can weigh up to 3,000 pounds and grow up to 16 feet long.
These social animals can live in both salt and freshwater. Beluga whales live around the world and are even found in Arctic waters where their layer of fat (blubber) protects them from the icy cold. Their lack of dorsal fin helps them swim through the ice. Beluga whales prefer to live in coastal bays and inlets, swimming from salt and freshwater with ease. They are easy to identify with their distinctive foreheads and white-colored bodies.
2. River Otter
Unlike sea otters, river otters spend quite a bit of their time on dry land where they like to rest, play, and raise their young.
River otters make their homes across North America from as far south as Florida to as far north as Alaska. While sea otters live only in saltwater, river otters like to make their homes in brackish, fresh, or saltwater. These playful mammals have a thick, double coat to keep them warm in cold water. Otters are members of the weasel family, which also includes minks, skunks, ferrets, and badgers.
3. Tucuxi Dolphin
Tucuxis are slower swimmers than other dolphins but swim faster than the Amazon River dolphins.
Two species of river dolphins live in the Amazon basin; the tucuxi ( Sotalia fluviatilis ) and the Amazon River dolphin. While the Amazon River dolphin lives only in freshwater, the Tucuxis dolphins can be found not only in the freshwater of the Amazon River but swimming in the sea as well. These shy and social dolphins are only found in the Amazon and Orinoco basins in South America.
4. Manatee
These gentle giants, also known as “sea cows,” eat seagrass, aquatic plants, mollusks, and fish.
Out of these three species, the Amazonian only lives in freshwater, but the African and West Indian manatees move between freshwater and saltwater. It’s thought that centuries ago, sailors may have mistaken manatees for mermaids . Interestingly, manatees’ closest living relatives are elephants.
5. Diadromous Fish
With their famous annual journey back to freshwater to spawn, Pacific salmon are the most well-known of the diadromous fish.
Diadromous fish spend some of their time in saltwater and some in freshwater. Pacific salmon , for example, spawn in freshwater where they live for a few months until they undergo, smoltification (a physiological change where they adapt to living in the ocean) and return to the sea. As adults, they migrate back to freshwater to lay their eggs. Other diadromous fish include Atlantic sturgeon, striped bass, river herring, and brook trout.
6. American Eel
Female American eels can lay four million eggs, and then die after mating.
American eels spend most of their time in freshwater, however, when mature they travel thousands of miles to the Sargasso Sea in the Atlantic Ocean to spawn. The only eel to live in freshwater in North America, American eels spend most of their lives in rivers and estuaries. These eels are a popular food in sushi dishes but must be cooked as they are toxic when eaten raw.
7. Sea Lamprey
Native to the Atlantic Ocean, sea lampreys have become an invasive species in the Great Lakes, where they had a devastating impact on the local fish population.
Sea lampreys , or vampire fish, have long snake-like bodies and sucker-like mouths. They spend the majority of their lives in saltwater oceans, returning to freshwater rivers and streams to lay their eggs. The larvae that hatch from the eggs are called ammocoetes. Ammocoetes live in freshwater for four to seven years until they undergo a metamorphosis that allows them to return to live in the ocean.
8. Saltwater Crocodile
Saltwater crocodiles have 66 teeth which can grow up to five feet long.
These ancient beasts can live in a variety of water types, salt, brackish, or freshwater. Saltwater crocodiles have salt-excreting glands, called lingual salt glands, which help them adapt to saltwater by managing their electrolytes. These impressive beasts, the oldest living species, can grow on average up to 17 feet in length and weigh 1000 pounds.
9. Bull Sharks
Bull sharks are uniquely adapted to survive in freshwater thanks to special glands near their tails and adaptions in their kidneys.
Most sharks only live in saltwater oceans, but the bull shark can tolerate both saltwater and freshwater. Sometimes called “river sharks,” bull sharks typically live in warm, coastal waters, yet they are adapted to freshwater as well and sometimes swim upstream in freshwater rivers. Though bull sharks don’t actively seek out humans to attack, their habitat is the type of water humans like to swim in, and bull sharks are highly territorial.
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