About Animals: The Basic Invertebrate Groups

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Animals Animals Animal Facts Habitat Facts Animal Pictures From Laura Klappenbach, your Guide to Animals Welcome to the Animals / Wildlife Newsletter, a weekly newsletter published by About.com's Animals / Wildlife website. For more about animals and wildlife, be sure to stop by the blog or browse the growing library of animal profiles. The Basic Invertebrate Groups  About 97 percent of all known animal species are invertebrates. Many of these species are classified in one of eight basic groups (although it should be noted that these basic groups provide a simple overview of invertebrates; there are in fact over 30 phyla of invertebrates). This article explores invertebrate classification in order to better understand the diversity and common characteristics of invertebrates. Search Related Topics:  invertebrates  arthropods  cnidarians Arthropods  Arthropods (Arthropoda) are a group of invertebrate animals that includes centipedes, millipedes, spiders, mites, horseshoe crabs, scorpions, insects and crustaceans. Search Related Topics:  arthropods  invertebrates  Invertebrates  Invertebrates are animals that do not have a backbone or a bony skeleton. Scientists have identified close to one million living species of invertebrates but this represents only a small fraction of the total number of invertebrates alive today.  Search Related Topics:  invertebrates  metazoa  animals The Basic Reptile Groups  Reptiles are a group of cold-blooded tetrapod vertebrates that diverged from ancestral amphibians about 340 million years ago. There are two characteristics that distinguished early reptiles from amphibians and enabled them to colonize terrestrial habitats more extensively than their ancestors, scales and the ability to lay hard-shelled amniotic eggs. Scales protect reptiles from abrasion and loss of body moisture. Search Related Topics:  reptiles  snakes  lizards Related Searches Animals Wild Life Animals Wildlife of Animals Help the Animals Snakes Facts Featured Articles Facts About Reptiles Turtles Side-Necked Turtles Hidden-Necked Turtles Chordates Vertebrates   More from About.com Run Your First 5K Even couch potatoes can be ready for a 5K with just a couple months of training. Read more...> Help! I'm Too Busy Time and stress management tips to help you feel as though you have more time. Read more...> This newsletter is written by: Laura Klappenbach Animals Guide Email Me | My Blog | My Forum   Sign up for more free newsletters on your favorite topics You are receiving this newsletter because you subscribed to the About.com Animals newsletter. If you wish to change your email address or unsubscribe, please click here. About.com respects your privacy: Our Privacy Policy Contact Information: 1500 Broadway, 6th Floor New York, NY, 10036 © 2013 About.com   Must Reads Animals A to Z What is Evolution? Basic Animal Groups Facts About Animals Animal Characteristics   Follow me on: Advertisement