External Anatomy of a Frog (Toad) | Zoology (2024)

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External Anatomy of a Frog (Toad) | Zoology? ›

Though larvae have tails, adult frogs are tailless. An adult frog has a stout body which is differentiated into head and trunk. Other external features are a pair of nostrils, protruding eyes, a membranous tympanum (ear), slippery/warty moist skin and webbed limbs.

They differ from most frogs because they have dry skin, warts, crests behind the eyes, and parotoid glands. The parotoid glands produce a poisonous secretion that helps the toad defend itself from predators. This substance, called a bufotoxin, can cause death in small animals and allergic reactions in humans.

The body of a toad is divisible into head, trunk and limbs. Head and trunk are not separated by a flexible neck; this condition is very suitable for aquatic (aqua = water) life. The adult has no tail.

Nostrils: The nostrils, called external nares, lead directly to the mouth and give the frog its excellent sense of smell. A frog can take in air in through its nostrils and down into its lungs.

Frogs have moist and smooth skin. Further, frogs have teeth in their upper jaw. Most importantly, their eyes stick out farther than that of a toad. Finally, they have longer hind legs when we compare them to that of a toad.

An adult frog has a stout body which is differentiated into head and trunk. Other external features are a pair of nostrils, protruding eyes, a membranous tympanum (ear), slippery/warty moist skin and webbed limbs.

The hind legs are short relative to other frogs' legs and the hind feet have long, unwebbed toes. There is no tail. The skin is dry and covered with small wart-like lumps. The colour is a fairly uniform shade of brown, olive-brown or greyish-brown, sometimes partly blotched or banded with a darker shade.

Unlike frogs, male toads not only have two testicl*s (inside their body, like in birds and fishes) but they also have two strange organs just above the testicl*s. These are called “Bidder's Organs” and are almost as big as the testicl*s – sometimes even bigger.

Toad warts are natural bumps on a toad's back. Toads have larger lumps behind their eyes. The bumps and lumps are glands. The glands produce a whitish goo that is a foul-tasting and smelly poison.

Amphibian skin is soft and moist with no scales. The skin may be smooth, except for toads, which have skin that is rough and wart-like. There are no claws on the toes of amphibians. One way to distinguish a salamander from a lizard is to examine the toes for claws.

Do toads have external ears? ›

Frogs do not have external ears like us. However, they do have eardrums and an inner ear. The frog ear is called a tympanum and is the circle you see behind a frog's eye.

External fertilization, employed by most frogs and toads, involves a male gripping a female across her back, almost as if he is squeezing the eggs out of her. The male releases sperm over the female's eggs as they are laid.

Some species of frogs and toads show young larvae (tadpoles) wearing external gills. When they grow larger than 10mm the external gills are covered by a special pocket of skin and become internal gills.

One of the least familiar differences between toads and frogs is that toads have no teeth, while all frog species have teeth. But frogs' teeth resemble sandpaper–just right for holding onto the insects they eat.

Frogs usually have big, bulging eyes, while toads' eyes are more subtle in appearance. One of the biggest physical differences between frogs and toads is their skin. While frogs have smooth or slimy skin that is moist, toads have thicker, bumpy skin that is usually dry.

Frogs use their long powerful legs to jump and hop around. Toads actually prefer to walk rather than hop. If they do jump/hop, they only move short distances. As such, they don't really need long legs like a frog does so their legs are relatively short.

Respiratory System

Frogs have such thin skin that some of the oxygen and carbon dioxide exchange directly through the pores. Most gas exchange takes place by breathing oxygen into the lungs and expelling carbon dioxide. Open the frog's mouth and stick a probe down the slit in the back of the throat called the glottis.

The frog body may be divided into a head, a trunk, and limbs. The flat head contains the brain, mouth, eyes, ears, and nose. A short, almost rigid neck permits only limited head movement. The stubby trunk (or torso) forms walls for a single body cavity, the coelom.