Amphibians

When Carl Linnaeus set out to classify animals he struck upon the term Amphibia to describe creatures that lived "double lives" in the water as well as on land. While this classification originally included reptiles, today there are three recognized groups of amphibians - tailless (e.g. frogs and toads), salamanders, and caecilians. These cold blooded animals typically live in moist areas and use their skin in addition to their lungs for oxygen exchange. The skin is kept moist with mucus to facilitate breathing. Amphibians are cold blooded and typically live either in the ground and ground litter or near water.  The prominent exception is toads which are abundant in some deserts. The primary reproductive mode for amphibians is by laying eggs which are cared for in a variety of ways - from being carried around until maturity in the parent's mouth to simply being laid in a suitable location and left there. A distinguishing feature of amphibians is that many species go through distinctive life stages - starting eggs, hatching as water breathing juveniles with gills and maturing into adults with air breathing lungs.

Looking back at the fossil record amphibians preceded reptiles and large dinosaurs in their development and were likely among the first creatures to make sound by expelling air from their lungs. Several groups of amphibians, including some that were much larger than those found today, no longer exist. The current amphibians developed relatively recently and are relatively poorly understood and described due to their secretive habits.  Additionally there are fewer Amphibians (between 2,500 and 3,000) than any other animal group.

The most recognizable members of this group are frogs and toads. Inhabitants of marshy areas are likely familiar with the mating calls of both toads and frogs. Egg masses are generally laid in water and small tadpoles emerge which look quite different from adults and breath water through their gills instead of the lungs of adults and lack legs. As the tadpole develops into an adult the tail is gradually "absorbed" by the body and legs begin to appear. Adults lack gills and can live terrestrially or, in the case of frogs, both aquatically and terrestrially.

True frogs (family Ranidae) have a distinctive appearance that is common throughout this family with streamlined bodies; moist and smooth skin; long, slender legs; and webbed toes on their hind legs. Frogs are carnivores eating most anything that moves (including other frogs) and can be seized by their powerful mouths or quick tongues.

Toads (family Bufonidae, Hylidae or Pelobatidae) at first look much like their frog cousins, but their morphology is quite different with shorter legs and slower movement. Dry, warty skin is the most obvious distinguishing feature of toads - with some toads having paratoid glands on their skin that can excrete toxic fluids. The reproductive cycle of toads and frogs is identical, except toads generally lay their eggs in shallow, sometimes ephemeral pools of water and morph into tiny hopping toads after only a brief developmental period. Toads are primarily terrestrial once they become adults returning to water only to breed.

Tree toads (they aren't true frogs) are a rare type of cold blooded animal in that they live most of their life away from the ground.

Looking more than a bit like lizards with their short legs, elongated bodies, and tails, salamanders are easily recognized by their soft, moist skin. Some salamanders spend their entire lives away from water, laying their eggs in decaying wood instead, while mud puppies spend their entire lives in water. Salamanders are rarely seen because they hide from intense heat and dry conditions while feeding mostly at night. While some salamanders "lose" their tails this is most often in response to a threat and to avoid being eaten. Most salamanders lay eggs, although a few bear live young.  The size of adult salamanders ranges from a scant 2 inches in length to as much as 5 feet!

Newts are a distinctive class of salamanders that are often brightly colored and terrestrial. These animals were once considered to "rain down" because they often emerge and travel shortly after or during rain storms. Although newt legs are short they can move quickly and often do.

Can you pick out the salamander hiding in this pile of brush? The conspicuous dots are a common feature of salamanders.

Resembling snakes these amphibians are most common in humid tropical environments.  These peculiar creatures not only lack legs, but they also have only a one lung and are often tailless too! Unfortunately, relatively little is known about caecilians compared to other groups.