Is a newt a salamander?
Yes, but a salamander is not always a newt. Confused? The word "salamander" is the name for an entire group, or scientific order, of
amphibians that have tails as adults. This includes animals commonly known as newts and sirens. 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. The term "newt" is sometimes used for salamanders that spend most of each year living on land. The name "siren" is generally given to salamanders that have lungs as well as
gills and never develop beyond the
larval stage. Other names salamanders go by include olm, axolotl, spring lizard, water dog, mud puppy, hellbender, triton, and congo eel. Whew!
From head to toes
Most salamanders are small, and few
species are more than 6 inches (15 centimeters) long. Their heads are narrow and they have small eyes. Sirens have only two legs, but the other salamander species develop four legs as adults, with fleshy toes at the end of each foot. Some species, like
paddle-tail newts Pachytriton labiatus and male
palmate newts Triturus helveticus, have fully
webbed feet with very short toes to help them climb on slippery surfaces. Those that like to dig, such as the
tiger salamander Ambystoma tigrinum, have no webbing at all on their feet. A salamander’s hind legs grow more slowly than its front legs. (Frogs and toads are just the opposite. Their hind legs grow more quickly than their front legs.) All four legs on a salamander are so short that its belly drags on the ground. The exception to this is the sirens. They don’t have hind legs at all! Their long, strong tails are flat to help sirens swim like a fish, with the tail flapping from side to side.
Take a deep breath
Different members of the salamander order have developed different ways of breathing. Sirens keep their gills all their lives, allowing them to breathe underwater. Others, such as the tiger salamander, lose their gills as they grow older and develop lungs to breathe air. But most, like the
arboreal salamander Aneides lugubris and the
California slender salamander Batrachoseps attenuatus, don’t have lungs or gills as adults. Commonly called lungless salamanders, they breathe through their skin and the thin membranes in the mouth and throat.
All wet!
Newts usually have dry, warty skin and salamanders have smooth, slick skin. But of course there are exceptions! But no matter what it may look or feel like, salamanders and newts need to keep their skin moist. If they get too hot and dry, they could die.
Land or water or both?
Since salamanders need to stay cool and moist to
survive, those that live on land are found in shady forested areas. They spend most of their time staying out of the sun under rocks and logs, up in trees, or in
burrows they’ve dug in the damp earth. Some will seek out a pool of water where they can breed and lay their eggs, before returning to the land. Others, like
sirens,
olms Proteus anguineus, and
axolotls Ambystoma mexicanum, spend their entire lives in the water.
Life cycle
Different salamander species have different
life cycles, too. Some breed, lay their eggs, and hatch on land. Others, such as some newts, breed and lay eggs in the water. When the eggs hatch, the larvae grow up in the water, then return to the land as adults. Still others, such as the
giant salamander Andrias sp
. and the
hellbender Cryptobranchus alleganiensis, spend all the stages of their life cycle in water. Lungless salamanders have eggs that hatch directly into small salamanders, skipping the larval stage entirely!
Bringing up baby
Most salamander species hatch from eggs. Female salamanders that live entirely in the water lay more eggs—up to 450—than those that spend some time on land. The
California newt Taricha torosa lays a clump of 7 to 30 eggs on underwater plants or exposed roots. The eggs are protected by a
toxic gel-like membrane. Lungless salamanders such as the
spiny salamander Plethodon sp. are devoted parents that share egg-guarding duties. They curl their bodies around the eggs and turn them over from time to time. This protects the eggs from
predators and from fungal infections. Some mother newts keep their eggs safe by wrapping leaves around each one as they are laid—up to 400 eggs! Salamanders in the larval stage of their development are called efts.
What’s on the menu?
All salamanders are
carnivores, but they are seldom in a hurry to catch their meals. Because they move more slowly than other meat eaters, salamanders tend to eat slow-moving, soft-bodied creatures such as earthworms, slugs, and snails. Larger species may eat fish, crayfish, and small
mammals such as mice and shrews. They might approach their target slowly, then make a quick grab with their sharp teeth. Or they might hide and wait for a tasty meal to pass close enough to snatch. Several species can flick out their tongues to catch their food as it goes by.
Staying safe
Would you want to eat something that tasted awful or hurt your mouth? Probably not! Salamanders have some special ways to keep from becoming another animal’s next meal. Most salamanders, such as the
red-spotted newt Notophthalmus viridescens, have brightly colored, poisonous skin. The bold color tells predators that the newt is not safe to eat. Many salamanders have glands on the back of the neck or on the tail. These glands can secrete a poisonous or bad-tasting liquid. Some species can even shed their tail during an attack and grow a new one later. The
ribbed newt Pleurodeles waltl has needlelike rib tips. It can squeeze its muscles to make the rib tips pierce through its skin and into its enemy, teaching it a sharp lesson! The
California salamander Ensatina eschscholtzii stands high on its legs and waves its tail to scare away danger.
Humans: the biggest enemy
Unfortunately, people are the salamanders’ worst enemy. Humans continue to pollute and destroy wetland
habitats. Remember, these amphibians need water to survive. Filling in their ponds, using
pesticides, and rerouting water for our own water needs has caused declines in many salamander
populations. We need to help conserve remaining habitats and provide new gardens and parks for these unique creatures.
http://www.sandiegozoo.org/animalbytes/t-salamander.html
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