Show Description:

National Geographic Animal Videos are documentary style pieces covering various topics, such as: Amphibians lead double lives?one in water and one on land. Many begin life with gills, then develop lungs as they age. There are about 10,000 bird species, found in every shape and size, from the tiny hummingbird to the majestic condor. Insects, spiders, centipedes, and other creepy-crawlies are commonly called bugs. Bugs are invertebrate animals and usually wear a hard external skeleton. Fish are ancient water-dwelling creatures found all over the globe. They are the world's oldest vertebrates, with the first fish appearing some 500 million years ago. Invertebrates comprise all the animals on Earth without spines, from the tiny zooplankton to the giant squid. Nearly all mammals give birth to live young, and all are warm-blooded, maintaining a near-constant body temperature regardless of environmental conditions.