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American Bullfrog
adult male
Conservation status
Scientific classification
R. catesbeiana
Binomial name
Rana catesbeiana
(Shaw, 1802)
Lithobates catesbeianus distribution.png
  Native range     Range as an invasive species

The American Bullfrog (Rana catesbeiana or Lithobates catesbeianus) is a semi-aquatic frog. It belongs to the family Ranidae, or "true frogs." The name "bullfrog" was given to the frog because males make a sound like a bull when mating with a female. Bullfrogs are native to most of North America, Canada, and Mexico; but they have been seen in South America, Asia, Western Europe, and the Caribbean as well. The ones that live in colder climates hibernate during winter. However, bullfrogs in warmer climates are active all the time.

Bullfrogs can adapt and live almost anywhere if there is water nearby. They can eat rodents, insects, small fish, arachnids, small birds, crustaceas, small mammals, worms, and other frogs. Because of this, they have been blamed for many animal extinctions. Bullfrogs live in large bodies of water such as swamps, lakes, and ponds. They like to stay near the edge of the water. Bullfrogs eat mosquitos' larvae, which can decrease the mosquito population. They do not move during the day, except if there is food nearby or when threatened. During a rainstorm, they may travel on land. They travel in search of a new habitat.

A female bullfrog can lay up to 20,000 eggs. Bullfrog tadpoles take about a year to become a young frog. Males will stay behind and take care of the tadpoles. Males are territorial and will attack any animal, including their own kind, if they come near them.

Bullfrogs can live up to four years. One captive bullfrog lived 16 years. Some people keep bullfrogs as pets. Bullfrog legs are eaten by humans, and students dissect bullfrogs in science classes.


The American bullfrog (Rana catesbeiana) is its common name. It is one of 90 species of the genus Rana, which is Latin for "frog." Catesbeiana came from Mark Catesby, an English naturalist, who first discovered the bullfrog. The American bullfrog is also known as Lithobates catesbeianus. The parent family for Rana is Ranidae, or "true frogs." Lithobates is a combination of two Greek words: "λίθος" and "βαίνω". The word "λίθος," as a feminine noun, means gemstone or smooth stone. "βαίνω" is a Greek verb which means "walk."


The American bullfrog is the largest of the "true frogs" family. Bullfrogs can reach a length of 6 to 8 inches (15 to 20 cm) and can weigh up to 1.7 pounds (770 g). Females are larger than males. Bullfrogs are either brown or green. They also have darker spots on their back. Bullfrogs have webbed feet for swimming. They can leap up to 6 feet (1.8 m). Male bullfrogs can be heard roaring when mating with a female. Males also have bigger tympanic membranes which cover their ears. Bullfrogs have brown or gold eyes. They also have broad flat heads and bodies. The mouth of a bullfrog is small and has tiny teeth inside.

Bullfrogs usually live 4 to 5 years. There was one captive bullfrog that had lived 16 years. Bullfrogs are good at hearing. A group of bullfrogs is called an "army."

Bullfrogs have toxic skin, though it is not harmful to humans. The toxins make it less likely that other animals will eat them. Many bullfrogs are known to have many viruses and bacteria. However, only a few of them are important to nature. Bullfrogs were blamed for an intraerythrocytic virus outbreak in Canada in 1997. They were also blamed for a chytrid fungus that spread into Arizona in 2000. The chytrid fungus is believed to be one of the major causes of the decline in amphibian populations. Many bullfrogs can have many parasites including helminths, trematodes, nematodes, protozoans, and leeches.

Habitat and distribution

Rana catesbeianaPCSL13327B
A bullfrog in a lake. A lake is one of many habitats of a bullfrog.

Bullfrogs are semi-aquatic frogs. They are known to live near lakes, swamps, rivers, and ponds. They spend most of their time swimming. Bullfrogs are an important food source for other wildlife, providing protein for them. If there is a drought, bullfrogs will leave their habitat. During a rainstorm, they move more quickly and are seen in large groups.

Bullfrogs live in most parts of Canada, Mexico, and the United States. They have been introduced to Argentina, Belgium, Brazil, China, Colombia, Cuba, Dominican Republic, Ecuador, France, Germany, Greece, Indonesia, Italy, Jamaica, Japan, Malaysia, the Netherlands, Peru, Philippines, Puerto Rico, Singapore, Spain, Taiwan, Thailand, the United Kingdom, and Uruguay. They were imported by ships to other parts of the world.


Bullfrogs were first described in 1802 by George Shaw. Shaw described the bullfrog in his book General Zoology or Systematic Natural History. A bullfrogs call is a slow deep g-r-r-u-u-u-u-m. Young bullfrogs will make a high-pitched chirp before going in the water. They do this when they feel threatened. Bullfrogs are more active at night. During the day, bullfrogs may rest under vegetation. Males are territorial and will attack any animal, including their own kind, if they come near them. They will jump, wrestle, and even chase any animal away.


Bullfrogs in the northern United States hibernate during the winter time. They hibernate in mud at the bottom of ponds and rivers. They can breathe underwater as long as they can get oxygen through their skin. They can also close their nostrils when they are underwater. While hibernating, bullfrogs can slow their heart rate and metabolism down.

Bullfrogs in southern U.S. states are active all the time. They may hibernate for a short time during cold weather.


In a 1913 study, it was found that bullfrogs will eat any animal it can overpower and stuff down its throat. Bullfrog stomachs have been found to have rodents, baby muskrats, small turtles, snakes, frogs (including bullfrogs), birds, and a bat, as well as the many invertebrates, such as insects. Bullfrogs are also known to eat ducklings and tadpoles. Adults can help decrease the mosquito population by eating most of their larvae.Bullfrogs have teeth on the top of their mouths. Their tongues are capable of flipping their food into their mouths. Bullfrogs will eat at night.

In captivity, pet bullfrogs are given crickets, worms, small fish, rodents, and fruit flies. In the wild, they like to eat crayfish, water beetles, snails, and dragon fly larvae. Bullfrogs will also eat each other.


Bullfrog Tadpole
Bullfrog tadpoles can reach 6 inches in length.

The mating season begins in spring and ends in early summer. Females are attracted to males who have territories that provide the most food. A male bullfrog grabs the female and begins roaring. A female bullfrog will make an aggressive call. The female lays her eggs on the surface of shallow waters, after which the male releases sperm on the eggs as fertilizer. A female can lay up to 20,000 eggs. The eggs hatch after four days. They are called "tadpoles" and live in the water, eating algae. Bullfrog tadpoles are larger in length than the tadpoles of other frogs. They become frogs in more than a year. In captivity, they can become frogs in twelve weeks. If a bullfrog tadpole remains as a tadpole for more than a year, it will become larger when it is an adult. Because of this, they will have a better chance of survival in the wild.

There are many predators such as larger fish, crustaceans, and some birds that eat some of the eggs and tadpoles. Because bullfrog tadpoles are not very active, they are less likely to be eaten by an animal. Bullfrog tadpoles also have an awful taste, which is another defense for them.

Development of tadpoles

Rana catesbeiana IMG 2680
Froglets will begin hopping out of the water and onto land.

Once the tadpoles become "froglets," they begin hopping out of the water and onto land. They lose their tails once they are at this stage. The froglets will stop using their gills and use them as lungs. They begin eating small insects. The froglets will stay near the water where they were laid. If there is a drought, they will search for a new habitat. At this time, froglets become easy prey to larger frogs, reptiles, raccoons, foxes, and birds. Froglets become adult bullfrogs four months after they begin hopping on land.

Conservation status and community impact

The International Union for the Conservation of Nature (IUCN) rates the bullfrog as "Least Concern." This is because they are found almost in every continent. "Least Concern" means that the bullfrog is not an endangered species. There are more bullfrogs in the southern United States than there are in the north. However, bullfrogs populations are decreasing because of habitat loss, water pollution, pesticides, and over harvesting.

Bullfrogs are an invasive species in Puerto Rico and in part of the western United States. They were brought there by fishermen who accidentally brought live frogs home with their fish or by pet owners who bought them to control pests in their yards. Bullfrogs have been blamed for making the California Red-legged Frog a near-threatened species. They have also been blamed for many other amphibian extinctions.

Human use

Bullfrogs being sold alive at a supermarket in China.

Bullfrogs are a source of food for the Southern and the Midwestern United States. People hunt bullfrogs at night near rivers. The bullfrogs' legs are cooked, while their backs are fried. In the state of California, people must have a license to catch bullfrogs for food. In China, bullfrogs are sold alive for eating. They are then killed and cooked with vegetables.

In schools, bullfrogs are dissected in biology classes. Usually, this is done in middle school. The dissecting is a method for teaching students the anatomy of a bullfrog.

Bullfrogs are also kept as pets. They are kept in aquariums or a terrarium. A terrarium is a tank decorated with plants and soil on one side. On the other side, there is water. A bullfrog would need one place for land and another for water.

Interesting facts about bullfrogs

  • Male bullfrogs make a sound similar to a bull, which is where the bullfrog gets its name.
  • Bullfrogs are nocturnal.
  • They have a natural toxin on their skin that tastes terrible to predators.
  • Bullfrogs can leap as far as ten times the length of their body.
  • Tadpoles can stay in the tadpole stage for up to two years before developing into frogs.
  • Water temperature determines how quickly tadpoles develop into frogs.
  • Iowa, Missouri, and Oklahoma claim the bullfrog as their state amphibian.
  • One of the most important senses for the bullfrog is hearing.
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