Insects are a major group of arthropods and the most diverse group of animals on Earth, with over a million described species, more than half of all known living organisms, with estimates of undescribed species as high as 30 million, thus potentially representing over 90% of the differing life forms on the planet. Arachnids are a class ...
Updated: Dec 28, 2009 11:29am PST
Vertebrates are members of the subphylum Vertebrata, chordates with backbones or spinal columns. Vertebrates comprise cyclostomes, bony fish, sharks and rays, amphibians, reptiles, mammals, and birds.
Updated: Jan 01, 2010 5:04am PST