The amphibian that went to college

StoryImage( ‘/Images/Story//Auto-img-118054372919595.jpg’, ‘Photo courtesy of‘, ‘This American toad is a member of the class Amphibia, which includes frogs and salamanders.‘);
StoryImage( ‘/Images/Story//Auto-img-118054384619593.jpg’, ‘Photo by Dr. Robert A. Hedeen’, ‘The ugly but beneficial toad wears a precious jewel in his head.‘);

My first encounter with the detailed anatomy of a vertebrate animal came many years ago in my first course in zoology at the University of Texas. A laboratory instructor unceremoniously dumped a preserved toad in front of me, and I went to work on it as per the instructions in the laboratory manual. In those days, the common American toad, Bufo americanus, was frequently used in freshman laboratories, but in recent decades it has lost its popularity with professors and has been largely replaced by the bullfrog—much to the approval of toads everywhere.

Toads are members of the class Amphibia, which includes frogs and salamanders. All amphibians have a skin that is pervious to water, so they must not venture far from water or risk death by desiccation. Likewise, the eggs of amphibians lack a waterproof shell, so they must be laid in water. Toad eggs are laid in strings of mucus, and frog eggs are embedded in a ball of mucus. Both pass through the tadpole stage during development. Early embryologists learned a lot about the development of higher animals by studying the developing eggs of toads and frogs.

Many individuals having only a casual acquaintance with the toad regard it as an ugly, deformed, grotesque creature, but I feel sure that toads appear quite beautiful and attractive to other toads. It is true, however, that in the eyes of man, the warty-skinned toad is not as handsome as a sleek-skinned frog, but the distinctiveness of the warty one’s eyes has long been recognized, Even Shakespeare was aware of this and wrote:

“Sweet are the uses of adversity,

Which like the toad, ugly and venomous,

Wears yet a precious jewel in its head.”

The pupil of the toad’s eye is black and oval in shape, and is surrounded by a broad band of gold. In Shakespeare’s time, this “jewel” was considered to be a good luck charm that protected you from evil spirits.

As a result of the mystique they have for some, many folk stories have arisen concerning them, all of which are untrue. Just because their skin is warty does not mean that if you handle one, you will develop warts. They do not squat on poisonous mushrooms or toadstools, and they do not exude a poisonous fluid, unless one considers toad urine to be poisonous, which they invariably pass if you pick one up. A few species of toads in the tropics manufacture a deadly poison, but none in North America does this. Our toads do have a gland on each side of the head that secretes an irritating fluid and is employed as a defense mechanism. A dog that playfully picks up a toad in his mouth will immediately reject it because of the burning irritation caused by the glandular secretion. The mutt is not harmed, but you can bet he will think twice before he snaps up another toad.

The toad should be regarded as a very beneficial animal. Some years ago, a government biologist estimated that each toad in North America was worth at least $50 as a destroyer of harmful insects. With inflation, it is impossible today to put a price tag on each of our chubby friends’ contribution. We can be sure, however, that toads are among the most valuable amphibians as far as man is concerned.

A toad’s appetite is amazing. One researcher found 65 caterpillars of the destructive gypsy moth in the stomach of a single toad. The same authority on the dietary habits of toads estimated that in three months, a single toad would devour up to 10,000 insects of various species. Unfortunately, some of these would be beneficial insects.

The toad’s tongue is attached at the front of the mouth and is elastic and sticky. It can be flicked out and back in with lightning speed, bringing in anything that might be perceived to be food. A forward lunge of the body by the strong hind legs, and the long, sticky tongue can do the job at a surprising distance. Most toads, however, will not be interested in a potential item of food unless it shows at least a slight bit of movement.

Once I was sitting in my yard smoking a no-filter cigarette and watching a toad nearby. As the cigarette burned down, I flipped the butt in the direction of the toad, and he seemed to stare at it. Then, a wisp of smoke emerged from the butt, and in an instant the tongue of the toad flipped out and ingested it. I thought he would immediately reject the foreign object, but he just sat there for a while before hopping off.

I surely hope the creature did not like the taste of tobacco and become addicted.

Dr. Robert Hedeen is a former resident of Maryland’s eastern shore and resided in the Chicago area from 1960 to 1971. He is a retired professor emeritus of biological sciences in the University of Maryland system. He has published more than 30 scientific papers, has written numerous magazine articles, and is the author of two books on the natural history of the Chesapeake Bay.

from the May 30-June 5, 2007, issue

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