Bullfrog or Bullfrog - Behavior and Characteristics

Bullfrog or Bullfrog: find out what this animal is like, its physical characteristics, character, behavior, etc. Due to its ferocity, voracity, and...

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Due to its ferocity, voracity, and great adaptability, the bullfrog is a species that threatens the survival of many other species, including other types of frogs and amphibians. It is therefore an invasive species. These frogs, which come from North America, colonize without restraint all types of ecosystems. Any place where there is a body of water is a possible target for the creation of impressive colonies of bullfrogs. Do you want to know why these frogs are so dangerous to the environments they inhabit?

In this section of PlanèteAnimal dedicated to frog species, we will talk in detail about the bullfrog, its characteristics, its habitat, its diet and its reproduction, all factors that have played an essential role in its development as an invasive species.

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  • America
  • Canada
  • United States

Origin of the bullfrog

The bullfrog is an amphibian of the family Ranidae which comes from the American continent, more precisely from North America, and is typical of southern Canada, eastern Mexico and all of the UNITED STATES. Even so, in some US states, this frog is considered an invasive species. For example, it arrived in California at the beginning of the 20th century, where it established itself as a dominant species which exerted strong competition on the local fauna.

These frogs have become an invasive species in many countries around the world. This is no coincidence, as this abrupt expansion is, of course, due to human intervention, as these frogs have been exported to become exotic pets, as well as to be eaten as gourmet foods.

The species is currently considered an invasive species, one of the most aggressive, in all countries where colonies of these frogs have formed, and has been declared one of the 100 most invasive species harmful and most destructive in the world.

Bull Frog Physical Characteristics

The bullfrog is the largest frog in North America. They have long hind legs, 25 cm long, which are longer than the body itself, which is about 20 cm long. These frogs can weigh more than 1 kilogram and measure in total from about 10 to 17 to 46 centimeters.A wild bullfrog can live around 10 years, while in captivity it can live up to 16 years.

The bullfrog's head is flat and fairly wide, with a fold of skin on both sides of the head, specifically from behind the eyes to the eardrum. It is in the eardrum that sexual dimorphism is found in bullfrogs, with males having a wider eardrum with a dark rim, while the diameter is smaller in females, which is the same size as their eyes. .

They have darker spots or mottling than the rest of the body, scattered over the torso, head and limbs. These extremities end in four-toed hands and feet, with interdigital membranes between all the toes of the hind legs except the fourth.

Bullfrog Habitat

Bullfrogs are one of the animals with the greatest potential for adaptation, which is why they are found near almost all bodies of fresh water, especially those where the temperatures are not too low .They prefer the stagnant waters of lakes, reservoirs, marshes or ponds, rather than those of rivers or, in general, waters where there are currents. The presence of this water is vital, because it is there that the life of an amphibian begins. In addition, these frogs are a food source for many animals typical of these aquatic ecosystems, such as herons, fish, such as the fearsome North American black bass, or alligators.

Although this species is native to North America, where it is present in almost all lakes and reservoirs, it has spread to different geographical areas with the wide variety of climates and ecological conditions. Currently, wild bullfrogs are found in Europe, Asia and South America. These frogs are considered an invasive species and are quite dangerous to the ecosystems they colonize.

Reproduction of the Bullfrog

Bullfrogs or bullfrogs, like other amphibians, can spend time in and out of water. But during the breeding period, from May to June, the bullfrog will need nearby fresh water, because that is where they will lay their eggs. Male bullfrogs court female frogs, after which mating takes place. The female frog then lays her eggs.

A bullfrog can lay about 20,000 eggs at one time. The fact that there are so many eggs is very important, because many tadpoles will not survive, as they serve as food for many predators. In addition, these eggs have a very special characteristic, namely that they have an unpleasant taste for different species of lizards, which serves to prevent them from devouring them before the time of hatching arrives. The eggs are laid on the surface of the water, where they float for a week before the tadpoles hatch.

These tadpoles will gradually mature, until those who manage to survive the many dangers that await them, like the many predators in the environment, end up turning into frogs. Its limbs gradually grow until they reach the size and shape of those of an adult bullfrog. It takes about 3 years to reach its final size.

Bull Frog Feeding

These amphibians have a carnivorous diet, as well as a noctophagous carnivorous diet, that is, they feed mainly at night. Among their many and varied prey are insects such as beetles or Lepidoptera, arachnids, worms and earthworms, snails, fish, lizards, turtles, lizards, rodents, bats, snakes and even birds. By seeing the list of its prey, you understand how dangerous a large colony of bullfrogs can be for the balance of an ecosystem.In addition, tadpoles feed mainly on algae, aquatic plants and some invertebrates.

The cry of the bullfrog

The piercing scream of bullfrogs, which they emit when threatened or cornered, can save their lives. Indeed, this powerful cry can be so startling to the predator that it ends up unhorsed long enough to allow the bullfrog time to escape.


¿Sabes que la rana toro está considered as one of the most aggressive and perjudicial invading species at world level? La Unión Internacional para la Conservación de la Naturaleza (IUCN) catalogs the dentro de las 100 species invasoras más agresivas, algo que no es de extrañar, pues la expansion de este anfibio por all el globo es brutal, así como los daños que ocasiona tanto in the middle as in the endemic species of the region.

Esto sucede debido a las altas capacidades adaptativas de la rana toro, que es capaz de amoldarse a las particularidades de una amplia gama de ecosystems, aprovechando todos los recursos que estos pueden brindar, haciendo así que las especies locales tengan menos recursos has known disposición, por lo que muchas de ellas ven abocadas to disappear dramatically.

Además estas ranas acaban con muchas especies ya que las utilizan como fuente de alimento, por lo que no es raro que en España s altaran las alarmas al encontrar ejemplares de rana toro en el Río Ebro. En España la rana toro ha sido incluida dentro del Catálogo Español de Especies Exóticas Invasoras y se toman medidas preventivas cada vez que se vistan ejemplares en el medio.

Pero este problema ha sido creado por nosotros mismos, los humanos, pues hemos sido nosotros los que hemos criado ranas toro para que sean tanto nuestras mascotas como parte de la dieta. Esto, combined with the fortaleza de este anfibio y su capacity para viajar largas distances, ha permitido that the rana toro is present in large territories and very distant geographically, estando extended por all Europa, especially in los Occidental countries.

Photos of Bullfrog or Bullfrog

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