The only place you’ll find non-human mammals in the Oklahoma Aquarium is in the Ozark Stream. In addition to beavers, river otters, and raccoons, the Ozark Stream features several fish that live in stream biomes. If you visit at feeding time, you might be lucky enough to see a river otter ride down a water slide!
The North American beaver (Castor canadensis) is the second largest rodent in the world. Smaller than only the capybara in South America, beavers can grow up to three-feet long and can weigh up to 60 pounds. Because they are rodents, their incisors (long front teeth) grow continuously throughout their lives.
They keep their teeth at a reasonable size by gnawing on wood, an action that works sort of like filing your nails. If you can get a close look, you’ll notice that these big teeth appear orange in color. This is due to the iron in the tooth’s enamel, which serve to protect their teeth from high acid concentrations in the wood they chew. They also have many other adaptations to support life in the water. Their webbed feet and paddle-like tail work together to propel them through the water at speeds up to five miles per hour.
Beavers are considered a keystone species because the wetlands that result from their dams support life for birds, fish, and many other animals. Beavers build dams to create small ponds to protect them from predators. They use these ponds as construction sites for their homes, known as lodges. Lodges are built from wood, mud, and stones and can usually be accessed from only underwater. They spend a lot of time in their lodges in our exhibit, so if you don’t see them out then you can watch them on the monitor on display in the gallery!
One of the most charismatic creatures in the Oklahoma Aquarium is the North American river otter (Lontra canadensis). River otters are similar to beavers in that they share many similar adaptations for swimming. Just like the beaver, they have strong tails, webbed feet, and a third eyelid known as a nictitating membrane that covers the eyes so they can see underwater.
River otters typically live solitarily or in pairs, but spend significant amounts of time playing in groups. They slide, roll, and dive, making them one of the most playful adult animals. They play more when food is abundant because some research suggests that this play is important for improving their hunting strategy. River otters are carnivores and they primarily hunt for fish, but they will eat any meat they can find, including eat frogs, crayfish, mollusks, insects, birds, and even small mammals. They have a very fast metabolism so they must eat a lot!
As urban populations have grown to outnumber countryside populations, raccoons raiding our trash cans have become a familiar sight, earning them the nickname “trash panda.” Raccoons' natural diets, however, don’t include human scraps; instead they eat fish, crayfish, and frogs as well as fruits, plants, and sometimes mouse and insect eggs. In addition to eating food that comes from streams, raccoons also like to live within 100 yards of freshwater so they can “wash” their food before they eat it. The real reason raccoons rinse their food is because wetting their paws makes the nerve endings on their paws extra sensitive. Raccoons don’t have particularly sharp vision so they rely on tactile information to inform what they’re eating.
The Ozark Stream is full of freshwater fish, including:
- banded darter
- black redhorse
- bluegill sunfish, longear sunfish, and redear sunfish
- cardinal shiner
- central stoneroller
- creek chub
- golden redhorse
- green darter and orange throat darter
- northern hogsucker
- redspot chub
- rock bass
- slender madtom
- smallmouth bass and spotted bass
- southern redbelly dace
Have you ever smelled a beaver’s behind? As gross as it sounds, there’s a fair chance you have and you might have even tasted it, too! Next to their anal glands, beavers have what is called a castor gland that produces castoreum, a thick brown liquid that smells like vanilla. Beavers use this scent to mark territory and communicate their presence to other beavers and predators. Humans use castoreum in perfumes and fruit flavorings and sometimes as a substitute for vanilla.
River otters are very talkative! Their repertoire of vocalizations ranges from clicks, chirps, chuckles, and shrill screams that can be heard from more than a mile away!
Conserving Stream Ecosystems
The stream biome is considered an endangered ecosystem in Oklahoma. Streams are on the decline as a result of sedimentation. Sedimentation is a natural process by which soil enters, but it can pollute our streams when there’s too much. Excess sedimentation is caused by practices such as irresponsible construction and it can cause damage to fish populations by raising stream temperatures, clogging gills, and interfering with egg/larvae production. If you are a Tulsa native, there are many opportunities for you to help monitor and clean our local streams. For more information on how to get involved, please visit our conservation page.
You are invited to watch our biology staff feed the beavers and otters everyday at 11 a.m and 3 p.m.
Written by Alyssa Rodriguez, February 2019.