Ten families are included in this group, that used to be considered a single family. The group is diagnosed by having the frontal bones fused to each other. The only poisonous lizards. 250 spp Micrurus tenere Texas coral snake. Dr. Allan H. Chaney, used with permission Snakes have two highly specialized means of capturing prey.
Some species are constrictors, which means they dispatch their prey by suffocation.
Venoms are classified as to their mode of action as hemotoxic and neurotoxic. Hemolytic - breaks down blood cells, vessels, and causes bleeding into internal body cavities. 12 out of 8000 bites from pit vipers reported yearly in the U.S. result in death Agkistrodon contotrix copperhead.