Amphibians are a group of animals that share a few characteristics -- such as going through the same life stages -- although they don't all look alike. The group includes frogs, salamanders and caecilians, which are legless salamanders that look a bit like snakes or big earthworms. Different species of amphibians might have specific defense strategies, there are some that are common in the group.
Eggs and Larvae
Eggs can't really protect themselves, but many amphibians lay eggs strategically to give them the best chance of surviving long enough to hatch. Some look for protected, out-of-the-way areas, and they tend to cluster their eggs within the protected zone. Others create strings of eggs in the hopes that predators will grab a few without following the entire line. Amphibians tend to spend their larval stages -- such as tadpoles -- in the water, and these small, immature larvae don't have many defenses except for speed. They swim quickly from predators, and they avoid grouping together so predators don't have an easy target.
Amphibians tend to go to two extremes when it comes to color. Many use camouflage to their advantage. Their skin matches the color of their typical habitat. Frogs that live in water might have lighter stomachs and darker backs to help hide from predators both below and above. Tree frogs might be green to blend in with the leaves, or salamanders could sport a mottled look to hide within the lichen. Some use stripes as well to break up their body lines, making them harder to see. On the other side of the color spectrum, some amphibians have brightly colored skin, making them easy to see. The skin color still works as a defense; it typically means the animal is poisonous, so it's avoided by predators.
Not all amphibians move the same way, but many of their movements are geared toward escaping predators. When a frog jumps, for example, the leaping motion can distract and disorient predators used to grabbing prey that moves in a straight line. Jumping often makes it impossible for predators to follow a frog's scent. Some caecilians burrow underground to avoid being eaten, and salamanders might coil and uncoil themselves as they move to confuse predators.
When running isn't an option, many amphibians fight back, or use an aggressive defense. Some amphibians puff up their bodies or assume an aggressive posture to make themselves look bigger and dangerous to eat. Salamanders often butt heads with a predator to warn him away. Several species of amphibians bite hard enough to deter predators, and they actively engage predators when necessary.
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