However even 18 hours is not considered abnormal for a Chihuahua. This includes naps.There are 2 types of sleeping. One is a lighter sleep (called slow wave) and the other is the deeper sleep (known as REM-Rapid Eye Movement). Dogs, just like humans do have these 2 different types of sleep.
Probably the best known snake in the world, the Rattlesnake is a pit viper found almost everywhere in the United States, and is capable of a deadly bite. Its trademark rattle strikes fear into anyone who hears it.
Most of the poisonous snakes in North America are what we refer to as pit vipers. Pit vipers get that name because of the heat-sensing pits beneath their eyes. They have triangular heads and pupils that look like slits. Vipers also have fangs that lay flat inside their mouths, attached to venom sacks.