TOAD (AS. tadige, tadie, toad: of unknown etymology). The common name applied to any one of the numerous species of tailless Amphihia belonging to the family Bufonidee and a few kin dred families. More than 100 species belong to the typical genus Bufo, which is nearly cosmo politan, but most numerously represented in tropical America, and absent from Papttsia, and the islands of the Pacific Ocean. Toads differ from typical frogs (Ranime) in the absence of teeth, in having the sacral diapophyses dilated, and the sternum wholly cartilaginous. Most have a short-limbed, thickset figure and warty skin, and the majority are quite terrestrial or burrowing, but some are aquatic and others arboreal or aberrantly modified. There are seven genera containing 15 species in the family, besides Bnfo. Noticeable among these are the common Australian toad (11yoLafraeluus Gouldi), which has a smooth skin: the repulsive egg-shaped, long-tongued, termite-eating Mexican species (Rhinophrynus dorsalis); and the large, warty, swimming toads of the East Indian genus Nectophryne.
The common toad of Eastern North America (Bufo lentiginosus) is a fair type of the group.
It reaches a length of about inches, and is brownish olive, with a yellowish vertebral line and some brownish spots; but it is exceedingly variable. The skin of young toads is nearly smooth, but that of adults is very warty. It contains many poison glands from which a milky somewhat acrid fluid exudes when the animal is roughly handled. This and the urine are harmless so far as man is concerned. hut have a protective value in making the creature distaste ful to many predatory animals.
The food of the toad consists of worms, in sects. and snails, which must be alive and mov ing in order to attract its notice. These are seized by the darting out of the tongue (see FROG), which is done so rapidly as to baffle all but very attentive observation. This fare is captured mainly during twilight and at night. The list of known foods embraces every sort of insect and larva that can be captured, including many most injurious to horticulture; and there is no doubt that a reasonable number of toads in a garden gives a valuable assistance in keep ing down pests. They do no harm at all. They molt the outer skin several times a year, strug gling out of it, and then swallowing it. When cold weather comes on they dig a hole in the ground, or find some warm, dry crevice among rocks, in a cellar or the like, and become dor mant. This power of hibernation, and their ability to endure deprivation of food and water, tend to a longevity very unusual in so small an animal, for toads under favorable conditions will live thirty years or more. The stories told of buried toads surviving for long intervals in solid clay, rock, and the like, are usually un worthy of belief. Experiment has shown that no toad can long endure deprivation of air, water, and food, although Buckland found that speci mens immured in blocks of porous stone and buried in moist soil remained alive after eighteen months. As soon as the torids emerge in the early spring their melodious piping is heard, and they make their way to water, where lighting between males and the mating of the sexes begin. After a few days long gelatinous ropes of black holoblastic eggs,' each about one-fifteenth of an inch in di ameter. are to he found coiled or matted in warm
ponds and roadside pools. Each female begins to breed when about four years old, and lays six to ten thousand eggs annually. These eggs rapid ly increase in size, and hatch in four weeks or less, according to weather. A detailed history by 11. Wright of their development may be found in the Standard Natural. History, vol. iii. (Bos ton, ISS5). The lame are considerably advanced when freed from the egg, and are provided with a peculiar temporary organ in place of the yet undeveloped mouth, by which they cling to weeds and similar supports; and with bushy external gills as breathing organs. There is no trace of limbs, but a swimming organ is present in the form of a large fin-bordered tail. Development proceeds rapidly. The true mouth is soon formed, and the tadpoles begin to feed upon the minute algae coating the bottom and floating on the sur face, and later eat animal substances. They are the best scavengers for an aquarium. They keep in shallow water near shore, but are preyed upon by newts, turtles, fishes, and predaceous aquatic insects. Gradually growth advances, the fore legs appear, and later the hind legs are developed and the tail and gill-tufts are gradually absorbed. (For experiments in rear ing tadpoles under various food-conditions, see Factors of Evolution, under EVOLUTION.) By midsummer the limbs are perfected, lungs have been formed, the tail is reduced to a mere stump, and the tadpoles creep out of the water as small toads. Here they encounter a host of enemies, birds, snakes, turtles, etc., so that a very small proportion escape to develop into adulthood, when they have few enemies except snakes.
The common toad of the Old World (Bufo vulgaris) is very similar to the American toad. It inhabits almost the whole Pahearctic region, eastward to China and Japan. India and the Malay Archipelago have a widely prevalent and very rough-skinned species (Bufo melanostictus), which has considerable power of changing color. The green toad of the Mediterranean region (Bufo riridis) is highly variable in color; and the natterjack and panther toads (qq.v.) of Western Europe much resemble it. The largest member of the genus is the huge aqua toad of tropical America, (See AcuA.) Various more distantly related amphibians are called 'toads,' as for example 'tree-toads' (see HYLA ; TREE FROG) ; the south American horned frogs (q.v.) of the cystignathine genus Ceratophrys; the Surinam 'toad' (see PirA), and others. Compare Elton; SPADEFOOT.
Fossil toads are quite rare, but are found scattered through the Tertiary formations from the Eocene upward, especially in Europe. Some very fine skeletons of toads, and even remains of tadpoles, have been found in the fresh-water Miocene deposits of Germany.
Consult: Cope, Batruchia of North America (Smithsonian Institution. Washington, 1889) ; Boulenger, Tailless Batrachiuns of Europe (Ray Society, London, 1306) ; Kirkland, "Habits, Food, and Economic Value of the American Toad," in Bulletin 46, Hatch Experiment Sta tion (Amherst, Mass., 1397) ; Gadow, Amphibia and Reptiles (London, 1901).
See accompanying Colored Plate.