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Harlequin Frogs True Toads and Relatives: Bufonidae - Behavior And Reproduction

glands female poison eggs

Many true toads are mainly active at night, when they come out of hiding to hunt for food. One of these, the Colorado river toad, lives in the deserts of the western United States. It avoids the hot daytime sun by staying underground and comes out at night to search the sand for beetles, snails, and other invertebrates (in-VER-teh-brehts). Invertebrates are arthropods and other animals without backbones. A few toads, including the Yungas redbelly toad, are active during the day.

Like most other frogs, toads have small poison glands in their skin. In many toads, some of the poison glands group together to form the paratoid glands, one of which is located behind each eye. When the toad feels threatened, it can ooze and sometimes squirt the milky poison from these glands. To some predators the poison tastes bad, but it can make others sick or even cause them to die if they swallow enough. Some toads, like the harlequin frog, do not have paratoid glands, but still are able to ooze enough poison through their other skin glands to ward off predators. This is an important defense tactic in the toads, many of which can only hop short distances and often cannot escape a predator by running away. Some toads, like the American toad, will even turn to face a predator, which puts the paratoid glands in the attacker's face. Not all predators are bothered by a toad's poison. The hog-nosed snake, for instance, makes toads a regular part of its diet.

Some toads, like the Yungas redbelly toad, do something different when they feel threatened. They strike a stiff pose, called the unken (OONK-en) reflex. In this position, they arch the back while holding up their red-bottomed feet and showing off the red of the belly. This display and the flash of color probably helps to remind predators that the toads have poisonous skin.

Many true toads mate during wet times of the year, often in the spring rainy season. In many species, a heavy rain will bring hundreds of males to ponds, streams, or newly filled pools of water where they begin calling. Toads often mate in the small pools that are only filled with water part of the year. These pools do not contain fish, which might eat the toads and/or their young. The typical male true toad has a balloonlike bit of flesh on its throat that inflates and deflates. This flesh, called a vocal sac, allows the toad to call. The males of most other types of frogs also have vocal sacs. Most of the true toads call with a steady trill. The American toad, for example, has a beautiful, long trill that lasts several seconds. Others, like the brown tree toad, have voices that are more like squawks than trills.

True toads usually call in choruses, which means that the males of a species group together and call all at once. The females hear the calls and follow them to the males. They mate when the male grasps the female from behind and holds on near her front legs, while the female lays her eggs in the water. In some species, like the Houston toad, the male may have to cling to the female's back for several hours before the female is ready to lay her eggs. Malcolm's Ethiopian toad mates differently than other true toads. Instead of the piggyback position that other toads and the vast majority of frogs use, the male and female of this species mate belly to belly.

Usually, the female lays her eggs, often hundreds of them, in a long string. The egg string may wrap around underwater plants, but sometimes it simply floats in the water. Most toads leave their eggs after they are laid. Toad eggs commonly hatch in a week or two into tiny tadpoles. American toad tadpoles, including their tails, are often no longer than a person's fingernail. The tadpole stage is also quite short, and they can turn into toadlets in just a few weeks. The toadlets are typically very small. People walking through the forest are frequently surprised at toadlets' tiny size. Baby American toads are also no bigger than a fingernail. Even the enormous marine toad has small toadlets.

A few toads, like the Roraima bush toad, probably have eggs that turn into toadlets instead of changing into tadpoles first. Scientists are not sure about the bush toad, however, because they have never watched an egg hatch.

Harlequin Frogs True Toads and Relatives: Bufonidae - True Toads, Harlequin Frogs, Their Relatives, And People [next] [back] Harlequin Frogs True Toads and Relatives: Bufonidae - Habitat

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