Noble Toad

Toads are a diverse and largely carnivorous group of short-bodied, tailless amphibians. Scientifically, there is no distinction between toads and frogs. Adult toads have a stout body, protruding eyes, cleft tongue, limbs folded underneath and the absence of a tail. Besides living in fresh water and on dry land, the adults of some species are adapted for living underground or in trees. The skin of thetoad is glandular, with secretions ranging from distasteful to toxic. Warty species of frog tend to be called toads. Frog warts are elevations in the skin where glandular toxins tend to concentrate. The distinction between frogs and toads is based on informal naming conventions concentrating on the warts rather than taxonomy or evolutionary history; some toads are more closely related to frogs than other toads. Frogs’ skins vary in colour from well-camouflaged dappled brown, grey and green to vivid patterns of bright red or yellow and black to advertise toxicity and warn off predators. Toads vary in length from about 3/4 of an inch (2 cm) to more than 9 inches (23 cm).

Frogs typically lay their eggs in water. The eggs hatch into aquatic larvae, called tadpoles, that have tails and internal gills. They have highly specialized rasping mouth parts suitable for herbivorous, omnivorous or planktivorous diets. The life cycle is completed when they metamorphose into adults. A few species deposit eggs on land or bypass the tadpole stage. Adult frogs generally have a carnivorous diet consisting of small invertebrates, but omnivorous species exist and a few feed on fruit. Frogs are extremely efficient at converting what they eat into body mass, which makes them an important food source for predators. Frogs are a keystone group in the food web dynamics of many of the world’s ecosystems. The skin is semi-permeable, making them susceptible to dehydration, so they either live in moist places or have special adaptations to deal with dry habitats. Frogs produce a wide range of vocalizations, particularly in their breeding season, and exhibit many different kinds of complex behaviours to attract mates, to fend off predators and to generally survive.

During extreme conditions, some frogs enter a state of torpor and remain inactive for months. In colder regions, many species of frog hibernate in winter. Those that live on land dig a burrow and make a hibernaculum in which to lie dormant. Others, less proficient at digging, find a crevice or bury themselves in dead leaves. Aquatic species such as the bullfrog normally sink to the bottom of the pond where they lie, semi-immersed in mud but still able to access the oxygen dissolved in the water. Their metabolism slows down and they live on their energy reserves. Some frogs can even survive being frozen. Ice crystals form under the skin and in the body cavity but the essential organs are protected from freezing by a high concentration of glucose. An apparently lifeless, frozen frog can resume respiration and the heart beat can restart when conditions warm up. At the other extreme, the striped burrowing frog regularly aestivates during the hot, dry season semi-desert climates, surviving in a dormant state without access to food and water for nine or ten months of the year. It burrows underground and curls up inside a protective cocoon formed by its shed skin.

Little is known about the longevity of frogs and toads in the wild, but some can live for many years. The oldest wild frogs have estimated ages of 14 years, including the four-year tadpole stage. Captive frogs and toads have been recorded as living for up to 40 years, an age achieved by a common toad (Bufo bufo). The cane toad (Bufo marinus) has been known to survive 24 years in captivity, and the bullfrog (Rana catesbeiana) 14 years.