copperhead pit viper with open mouth to strike showing fangs and glottis

adder agkistrodon america bite both camouflage coiled contortrix copperhead covered eastern endemic extreme eye fang fangs flicking glottis grass head heatsensing include inject located log moss mouth nausea north nostril open organ pain pit poison scales severe showing sides slither snake species strike swelling symptoms throbbing tingling tongue venomous viper