Frogs are amphibians and not reptiles. They are classified as part of kingdom Animalia, phylum Chordata, and class Amphibia. The word “amphibian” is derived from the Greek word amphibio which means "to live a double life". Amphibians begin their life in water before moving to land as they grow older. There are about 4,000 subspecies of amphibians on earth, the most common being frogs, newts, salamanders, caecilians,and toads. Frogs date back to the Jurassic period over 140 million years ago. They are found across the globe except in Antarctica. Frogs inhabit freshwater bodies but prefer lakes, marshes, slow-moving rivers, and ponds. They cannot live in salt water such as oceans and seas.
Characteristics Of Amphibians
Amphibians are poikilotherms, meaning they are cold blooded. They do not possess a developed body temperature regulation mechanism but instead depend on the temperature of the environment. They share this trait with reptiles. When frogs need to raise their body temperature, they move to an open place where they receive the heat from the sun. They hide under vegetation or move into the water when there is the need to drop the body temperature.
Amphibians produce unshelled eggs, unlike birds and reptiles who produce shelled eggs. The eggs of frogs are moist and jelly, a feature that makes them susceptible to desiccation when exposed to air. Salamanders and frogs deposit eggs into the water but some species of amphibians such as the terrestrial salamander deposit eggs in damp and concealed locations such as under logs and rocks. Frogs that dwell in the rainforest deposit their eggs on plant leaves which then drop into the water below as the tadpoles mature.
Moist Permeable Skin
Although caecilians have scales such as those in fish, a majority of amphibians possess a moist and permeable skin. They are sensitive to temperature especially from the sun forcing them to inhabit aquatic and wet environments to reduce the risk of dehydration. Frogs are found in arid environments such as the waxy monkey frog produce a thick solution of lipid to cover their skin and prevent loss of water.
Are Frogs And Toads Similar?
At first glance, one might not distinguish the differences between toads and frogs. Although they look similar, they are two distinct species. Both species are amphibians, but frogs need water to survive, unlike toads that last for long without water. Their exposure to moisture makes the skin of frogs smooth and slimy while toads have rough, dry and bumpy skin. Frogs have a narrow body compared to the toads. The most notable difference is the length of the hind legs, frogs tend to have longer and more powerful hind legs as compared to toads. Predators will always choose to eat frogs than the toads because of the bitter taste and burning smell released by the latter.