What has the head of a frog and the body of a lizard?
A salamander! You might have mistaken it for a lizard, but lizards are very different from salamanders. Salamanders have moist skin, while lizards have dry scales on their skin. Furthermore, lizards live their entire lives on land. Salamanders must reproduce in water.
Salamanders are characterized by slender bodies, short legs, and long tails. They are most closely related to the caecilians, little-known legless amphibians (Figure below). Most of the animals in the salamander order look like a cross between a lizard and a frog. They have moist, smooth skin like frogs and long tails like lizards.
Salamanders are found in most moist or arid habitats in the Northern Hemisphere, but can also be found south of the equator. They live on all continents except Antarctica and Australia. Salamanders live in or near water or on moist ground, often in a swamp. Some species live in water most of their life, some live their entire adult life on land, and some live in both habitats. Some salamanders live in caves. These salamanders have pale skin and reduced eyes as they have adapted to living in complete darkness in underground pools of water. The reduced eyes are similar to other organisms that live in caves or underground.
Salamanders are carnivorous, eating only other animals, not plants. They will eat almost any smaller animal, such as worms, centipedes, crickets, spiders, and slugs. Some will even eat small invertebrates. Finally, salamanders have the ability to grow back lost limbs, as well as other body parts. This process is known as regeneration.
Salamanders have developed ways not to be eaten. Most salamanders have brightly colored, poisonous skin. The bold color tells predators not to eat the salamander. Many salamanders have glands on the back of the neck or on the tail that give off a poisonous or bad-tasting liquid. Some species can even shed their tail during an attack and grow a new one later. Some salamanders stand high on its legs and waves its tail to scare away danger. One particular salamander, the ribbed newt, has needle-like rib tips. It can squeeze its muscles to make the rib tips pierce through its skin and into its enemy, telling the predator to stay away, a feature unique among the animal kingdom.
The marbled salamander (left) shows the typical salamander body plan: slender body, short legs, long tail, and moist skin. Caecilian (right) are a type of legless amphibian most closely related to salamanders.
How Do Salamanders Breathe?
Different salamanders breathe in different ways. In those that have gills, breathing occurs through the gills as water passes over the gill slits. Sirens keep their gills all their lives, which allows them to breathe underwater.
Species that live on land lose their gills as they grow older. These salamanders develop lungs that are used in breathing, much like breathing in mammals. Other land-living salamanders do not have lungs or gills. These are called lungless salamanders. Instead, they "breathe," or exchange gases, through their skin. This requires blood vessels that exchange gases to be spread throughout the skin.
How Big Are Salamanders?
Salamanders are generally small. However, some can reach a foot or more, as in the mudpuppy of North America. In Japan and China, the giant salamander reaches 6 feet and weighs up to 66 pounds (Figure below).
The Pacific giant salamander can reach up to 6 feet in length and weigh up to 66 pounds.
Classification of Salamanders
Salamanders belong to a group of approximately 500 species of amphibians. The order Urodela, containing salamanders and newts, is divided into three suborders:
- Giant salamanders, including the hellbender and Asiatic salamanders.
- Advanced salamanders, including lungless salamanders, mudpuppies, and newts. Newts are salamanders that spend most of each year living on land.
- Sirens. Sirens are salamanders that have lungs as well as gills and never develop beyond the larval stage.
Sirens have only two legs, but the other salamander species develop four legs as adults, with fleshy toes at the end of each foot. The legs on four-legged salamanders are so short that the salamander belly drags on the ground as the animal walks. Sirens have long, strong tails that are flat to help sirens swim like a fish, with the tail swinging from side to side.
- Salamanders live in or near water or on moist ground, often in a swamp.
- Salamanders can breathe with the help of gills, lungs, or their skin surface.
Use the resources below to answer the questions that follow.
Explore More I
- Spotted Salamander at http://animals.nationalgeographic.com/animals/amphibians/spotted-salamander/
- Where does the spotted salamander live?
- How does the spotted salamander discourage predators?
- Describe the diet of the spotted salamander.
Explore More II
- Giant Salamander as Big as a Dog at http://www.youtube.com/watch?v=buzqM1kHS5M (3:40)
- What led to the giant salamanders (Andrias japonicus) being threatened with extinction?
- What effect have dams had on giant salamanders?
- How does the habitat of the giant salamander differ from the habitat of the spotted salamander?
- What are the main characteristics of salamanders?
- Where do salamanders live?
- How do salamanders breathe?
- Describe the salamander known as the siren.