Harlequin Frogs True Toads and Relatives: Bufonidae

Physical characteristics: The marine toad is an enormous toad that can grow to as much as 9 inches (23 centimeters) long from snout to rump and weigh up to 2.2 pounds (1.5 kilograms). Sometimes it is called the giant toad, and in Belize, its nickname is the spring chicken. It is a dark-colored toad, often gray to brown, and sometimes reddish brown. Frequently, it has darker brown blotches and sometimes white spots on its back. It has large paratoid glands spreading from the back of its head to the front legs. It has a short, rounded snout, large eyes, and a noticeable eardrum on each side of its head.

The marine toad is an enormous toad that can grow to as much as 9 inches (23 centimeters) long from snout to rump and weigh up to 2.2 pounds (1.5 kilograms). (R. Andrew Odum/Peter Arnold, Inc.)

Geographic range: The marine toad naturally occurs in Mexico, Central America, South America, and southern Texas in the United States, but people have introduced it to many other places around the world, including Hawaii, Japan, the Philippines, Australia, and numerous islands of the West Indies. It is now a pest species in many countries.

Habitat: In its native areas within South, Central, and North America, the marine toad prefers to make its home in fields and open forests that have at one time lost their trees, perhaps to logging or to fires. It naturally breeds in ponds, at the edges of lakes, and in small pools that form in rainy parts of the year and dry up later on. This toad, however, is very adaptable. This means that it can adjust to live in other places, too. This has helped the toad move into new areas, including villages and towns, and make its home there.

Diet: The marine toad has a good appetite. It eats a wide variety of arthropods. It will sit down at night near a light in a town and spend hours flipping out its tongue to snap up insects that fly toward the light. It will also devour ants, cockroaches, and many other types of insects wherever it can find them. Besides arthropods, marine toads have a reputation for gobbling down cat food and dog food from the feeding dishes of family pets. They are also known to sometimes eat snakes, frogs, and even small mammals, like mice.

Behavior and reproduction: Marine toads often spend their days grouped together in an out-of-the-way spot. They become active at night, which is when they do the bulk of their hunting. Sometimes, they travel quite a distance at night. Scientists are not sure how they do it, but the toads are always able to find their way back home. In the spring mating season, male marine toads move to water, sometimes even swimming pools, and begin calling for females. They usually prefer a shallow spot on the shore of a pond or small lake, or at the edge of a marsh. Here, a male pushes up on his front legs and makes his call, which is a long, low trill that may last ten or twenty seconds. When many of them call at once, the sound is something like a tractor engine. When a female approaches a male, he climbs onto her back, and grasps her behind her front legs. The two toads may swim about with the male still riding on the female's back until she finishes laying her eggs. One female may lay a string of twenty-five thousand eggs, sometimes more, and a single string may stretch nearly 10 feet long. In about two weeks, the eggs hatch into small, black tadpoles. The tadpoles may group together in schools, just as fish do, until they turn into toadlets.

Marine toads and people: In 1935, people brought the toad to Australia with the hopes that it would eat a type of beetle that was destroying the sugar cane crop. The toads, which got the nickname cane toad, found plenty to eat besides the beetles. The toads bred quickly, and since they had very few predators, soon became pests themselves. The toads are still very common in Australia. One of the reasons that people in that country dislike the toads is that pet dogs sometimes try to eat them. The poison in the toad's skin can cause illness and sometimes death.

Conservation status: The World Conservation Union (IUCN) does not list this species as being at risk, but rather notes that it is becoming more numerous and spreading to more places around the world. The toad's skin poison can make other organisms sick and even kill the eggs and tadpoles of other frogs that share water with marine toads and their tadpoles. ∎