Biology Reference
In-Depth Information
Centuries of bad publicity notwithstanding, toads are extremely useful creatures. They consume
large quantities of insects, slugs, and other creatures that can seriously damage vegetables and other
desirable plants. Therefore, toads should be considered a welcome addition to anyone's grounds or
garden, and encouraged in any way possible.
Fortunately, the toad's sterling qualities are finally being recognized. In England, for example, there
is Madingly Toad Rescue, an organization named for the village of Madingly. Owing to heavy traffic,
toads were being killed wholesale as they crossed highways in an attempt to get to or return from their
breeding ponds. To save dwindling toad populations, Madingly Toad Rescue was formed by concerned
citizens.
With experience, this organization has developed several effective techniques for saving toads. For
instance, construction of amphibian tunnels under the highways has worked very well. However, the
most successful method has been for volunteers to pick up the migrating toads, put them in buckets,
and move them to the other side of the highway. Volunteers have also been aided in this endeavor by
temporary net fencing, which funnels and concentrates the toads so that they can be located and picked
up more easily.
While appreciation of toads tends to be a bit less dramatic on this side of the Atlantic, gardeners and
homeowners have increasingly come to understand the benefits of a healthy toad population. Indeed,
modern gardening topics often emphasize the value of toads, and gardening supply catalogs feature
little toad shelters that can be placed in gardens and around homes to attract these helpful tenants.
Toads are amphibians, with all that the term implies. The word is derived from the Greek
amphi,
of
two kinds, and
bios,
life, and refers to the fact that toads and other amphibians can live both on land
and in the water. Indeed, water or a very moist environment is required for amphibians to reproduce,
although many spend most of their lives on dry land.
Amphibians are a truly ancient race. They alone, among primitive vertebrates, first crept out of the
primal waters to set foot on land some 360 million years ago—an almost unimaginable span of time.
This was at the beginning of the Carboniferous period, when plants such as the giant tree ferns flour-
ished in immense profusion, eventually to be transmuted into coal beds by the labors of eons.
This was no small step for life on our planet. Up to that time, all vertebrates were aquatic; this trans-
ition, which might be termed the Great Leap for vertebrates, was truly monumental, because it paved
the way for the development of all vertebrate life on earth. Radical evolutionary changes were vital
in order to make this momentous transition from aquatic to terrestrial environment. The ability to ob-
tain oxygen from the air was critical; this required the development of lungs and moist skin that could
absorb oxygen. Limbs that could support these new creatures on land and enable them to move about
were also necessary.
Without other vertebrate predators, at least for a very long time, these early amphibians were able to
prosper and evolve further. Still, this evolution was incredibly slow in terms of our human time frame.
The earliest known ancestor of toads and frogs, barely recognizable as a very primitive prototype, dates
back to the early part of the Triassic period, about 240 million years ago, or 120 million years after
