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.
With the exception of the Coral Snake (see pix), all poisonous snakes in the USA are pit vipers. This means the Copperhead, the Cottonmouth, and many species of rattlesnakes. These snakes are really fat, with big, fat heads. They have slits for pupils. The rattlesnakes have rattles on the end of their tails.