frog

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Related to Batrachia: anuran, batrachian

frog,

common name for an amphibianamphibian,
in zoology, cold-blooded vertebrate animal of the class Amphibia. There are three living orders of amphibians: the frogs and toads (order Anura, or Salientia), the salamanders and newts (order Urodela, or Caudata), and the caecilians, or limbless amphibians (order
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 of the order Anura. Frogs are found all over the world, except in Antarctica. They require moisture and usually live in quiet freshwater or in the woods. Some frogs are highly aquatic, while others are better adapted to terrestrial habitats. Among the latter type, those with stout bodies and thick skins are often called toadstoad,
name applied to certain members of the amphibian order Anura, which also includes the frog. Although there is no clear-cut distinction between toads and frogs, the name toad
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, although the name toad is sometimes restricted to members of the most terrestrial family of the Anura, the Bufonidae.

Frogs lack tails in their adult stage. They have short, neckless bodies; long, muscular hind legs specialized for jumping; and webbed feet for swimming. The skin is smooth, usually some shade of green or brown, and often spotted. Frogs have no outer ears; their prominent eardrums are exposed on the sides of the head. The bulging eyes have nictitating membranes to keep the eyes moist. Adult frogs have lungs, but their breathing mechanism is poorly developed. At rest they breathe mainly through the mouth lining, filling the lungs only occasionally. When in wet places they also absorb much dissolved oxygen through their skins. Frogs have true voice boxes and are noted for their various sounds. Frogs capture insects and worms with their sticky, forked tongue, attached at the front of the lower jaw. Some large tropical species eat small mammals and snakes. A few frogs have skin glands that can produce irritating or poisonous secretions.

Most frogs hibernate in underwater mud and lay eggs in early spring. With few exceptions fertilization is external. The eggs—up to 20,000 at one time—are fertilized as they are laid in the water and are given buoyancy and protection by a gelatinous covering secreted by the female. The gilled, aquatic larvae, or tadpolestadpole,
larval, aquatic stage of any of the amphibian animals. After hatching from the egg, the tadpole, sometimes called a polliwog, is gill-breathing and legless and propels itself by means of a tail.
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, hatch after 3 to 10 days; by the end of their first summer most frogs have completed their metamorphosis to the air-breathing, tailless, carnivorous adult. In some species, however, eggs are laid on land, and the young hatch as tiny frogs. In a handful of species the female gives birth to live young, either as tiny frogs or tadpoles. Growth to adult size usually takes several years.

There are over a dozen families of frogs; the term "true frog" is often applied to members of the family Ranidae. The cosmopolitan genus Rana belongs to this family and includes many of the commonest frogs of North America, such as the bullfrog, R. catesbeiana, and the leopard frog, R. pipiens. Species of Rana are important laboratory animals; they are readily available and easy to handle and maintain. Field biologists have in recent years noticed declines in the populations of frogs and other amphibians worldwide. Although pollution and habitat destruction are contributing causes, the main culprit is believed to be a fungus, Batrachochytrium dendrobatidis, that causes a skin infection. Research has suggested, however, that outbreaks of the fungus are due in part to climatic changes possibly linked to global warming.

Frogs are classified in the phylum ChordataChordata
, phylum of animals having a notochord, or dorsal stiffening rod, as the chief internal skeletal support at some stage of their development. Most chordates are vertebrates (animals with backbones), but the phylum also includes some small marine invertebrate animals.
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, subphylum Vertebrata, class Amphibia.

Bibliography

See M. J. Tyler, Frogs (1983); C. Mattison, Frogs and Toads of the World (1987); M. Dorcas and W. Gibbons, Frogs (2011).

What does it mean when you dream about a frog?

Frogs are associated closely with water, which makes them symbols of the unconscious. Because of the widely known story of the prince who was turned into a frog and then back into a prince, frogs also represent transformation.

frog

[fräg]
(design engineering)
A hollow on one or both of the larger faces of a brick or block; reduces weight of the brick or block; may be filled with mortar. Also known as panel.
(engineering)
A device which permits the train or tram wheels on one rail of a track to cross the rail of an intersecting track.
(vertebrate zoology)
The common name for a number of tailless amphibians in the order Anura; most have hindlegs adapted for jumping, scaleless skin, and large eyes.

frog, panel

a brick having frog
A depression in the bed face of a brick or building block; used to provide a better key for mortar.

frog

frog
A relaxed free-fall position commonly used by sky divers.

frog

1
1. any insectivorous anuran amphibian of the family Ranidae, such as Rana temporaria of Europe, having a short squat tailless body with a moist smooth skin and very long hind legs specialized for hopping
2. any of various similar amphibians of related families, such as the tree frog

frog

2
Music US and Canadian
a. the ledge or ridge at the upper end of the fingerboard of a violin, cello, etc., over which the strings pass to the tuning pegs
b. the end of a violin bow that is held by the player

frog

3
a tough elastic horny material in the centre of the sole of a horse's foot

frog

4
a grooved plate of iron or steel placed to guide train wheels over an intersection of railway lines

Frog

(dreams)
Old dream interpretation books say that frogs are good omens and represent happiness and great friendships. From a more modern point of view, frogs may be considered symbols of the unconscious because they live in the water. Frogs also represent transformation of the positive kind.
References in periodicals archive ?
Cope, Check-list of the North American Batrachia and Reptilia; with a Systematic List of the Higher Groups, and an Essay on Geographical Distribution Based on the Specimens Contained in the U.