The Surinam Toad - A Strange Amphibian With Babies on Board

The Surinam toad has one of the strangest methods of reproduction of any amphibian. After the male and female have performed an elegant mating swim, the male Surinam toad carefully places the fertilized eggs on the female’s back. The eggs then sink and become embedded in the female’s spongy skin. A honeycomb-like structure develops, with one egg in each chamber of the honeycomb. Skin grows over the eggs and they gradually disappear from view. The eggs hatch inside the chambers. As the young toads grow they move around, creating a rippling appearance on the female’s back. Eventually the tiny toads break out of their chambers and escape into the world.

The Surinam toad (scientific name Pipa pipa) lives in the northern part of South America. It’s found in murky ponds, swamps and slow-moving streams, and in aquariums in other parts of the world. The toad has a wide body with a triangular head and a strange, squished appearance. It has tiny black eyes with no eyelids and webbed hind feet. Its long “fingers” have star-shaped structures at their tips, giving the toad an alternate name of star-fingered toad. The back legs are strong and are used for propulsion, but the front legs are weaker. The skin is often covered with warty protuberances. An adult toad is about five to eight inches long.

The Surinam toad has a big, black “T” extending over its underside, which gives the weird impression that the skin has been cut open and sewn together again! The toad’s mottled brown or grey color, flat body and habit of lying motionless on the bottom of a pond or stream make it look like plant debris, or a dead and decaying body.

The Surinam toad is almost completely aquatic, although it does move over land if its watery habitat dries up, or during heavy rains. It comes to the water surface every half hour or so to breathe air. The toad doesn’t have a tongue or teeth. It uses its long and sensitive fingers to probe for food and either lunges at its prey with its mouth or sweeps the food into its mouth with its fingers. The Surinam toad eats worms, insects, crustaceans and fish.

Like fish, the Surinam toad has a lateral line organ on the sides of its body. These organs developed in fish as an adaptation to aquatic life and are sensitive to water motion. They help the toad detect the movement of other animals in the water.

Mating takes place under water. The male toad doesn’t croak. Instead, he makes clicking and buzzing sounds to attract a mate. Once he has found a receptive female, the male climbs on to her back and wraps his front legs around her body in a process known as amplexus. While joined together the pair swim through the water, gracefully somersaulting as they swim. The female provides most of the propulsion with her hind legs. While the toads are upside down the female releases eggs, which fall on to the male’s belly. The pair then move into their starting position. The eggs drop on to the female’s back and the male fertilizes them. Then he gently gathers up the eggs with his hind feet, their webs expanded to form a fan, and positions the eggs carefully on his mate’s back. The eggs release a sticky substance which helps them attach to the female’s skin. This process is repeated multiple times. The female ends up with about 50 to 100 eggs on her back. Once all the eggs have been deposited, the male leaves the female, his job done.

Over a period of about twenty four hours the eggs sink into the female’s skin, which swells up to surround them. A covering forms over the eggs and for a while the presence of the babies is hidden. The baby toads take anywhere from 3 to 5 months to develop. As they grow their activity under the female's skin becomes more and more noticeable, and her skin "bubbles" with their motion. Eventually the young toads emerge from their chambers, leaving holes in their mother's skin. The female sheds her damaged skin after the babies leave and grows a new skin layer for the next breeding season.

The Surinam toad population is not endangered, but some other members of its biological family, which is known as the Pipidae, are not so lucky. The Myers' Surinam toad (Pipa myersi) has a similar reproductive method to its Pipa pipa relative. The Myers' Surinam toad lives in Panama, and is threatened by habitat loss due to deforestation and by water pollution.