Book SectionsTable of Contents
The Problem Puddle Power Frog-Friendly Backyard Why are we concerned about amphibians?
Wetlands - function/type Wetland issues
How to help amphibians
Community Green Plans
The word "amphibian" is derived from the Greek words "amphi" and "bios" which means two lives and refers to the aquatic tadpole and the terrestrial adult stages of all salamanders, newts, frogs, and toads. In a process called metamorphosis, which usually occurs over the course of a few weeks, the larval tadpole transforms into its adult frog and toad like form with which we are familiar.
In southern Ontario the first frogs begin to call the last week of March. In central Ontario frogs call the first week of April and in northern Ontario frog calls can be expected in late April. Calls and breeding periods may last several weeks for some species or just a few days for others. Consult "Familiar Amphibians and Reptiles of Ontario" for further information.
Amphibians hatch from eggs laid in the water and pass through a distinctive tadpole/larval stage (a month for toads and up to three years for bullfrogs). The larvae of most species are aquatic and possess gills and prominent fins. Frog and toad tadpoles graze on algae and small organisms in the water; larval salamanders and newts are carnivorous and feed on aquatic insects. During metamorphosis, they acquire legs and lungs. Significant changes in the digestive system coincide with
changes in feeding behaviour. Adult amphibians may live on land, but must return to water to breed and, in some cases, to hibernate. One species of salamander in Ontario differs from this typical pattern. The redback salamander lays its eggs out of the water. The female seeks a moist, rotting log within which to lay her eggs. Fully formed little salamanders hatch from the eggs!
During the cool winter months Ontario amphibians: 1
avoid frost by burrowing below the frost line (common toad),
2avoid frost by hibernating underwater in rivers, lakes, and
ponds (leopard frog). 3hibernate in forest leaf-litter where frost
is resisted by developing a sugary antifreeze and tolerating ice in
their body (wood frog). Mammals and birds use energy in food
to keep their bodies warm while amphibians and reptiles absorb
heat directly from their environment. As a result, amphibians do
not have to eat as often or as much as birds and mammals, and
they do not eat at all during the six months of winter hibernation.
Amphibians do not drink. They absorb water and much
of the oxygen they need through the skin, although they use
their lungs as well. Some species are active at night and avoid
the drying effects of the sun. Others shelter in moist habitats
under logs, rocks, leaves or mosses and ferns. Amphibians shed
their skin about once a week. Most frogs and toads eat their skin
which splits down the back and which they then pull into the
mouth with their front legs. We must not look at these animals
as if they were less advanced. Amphibians are superbly adapted
to their environments.
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