QUESTION: Is a Copperhead in the rattlesnake family?...I have two friends who are arguing this fact...(I think not..)...thank you!
ANSWER: Sorry-you're going to lose this bet. The Family for both is Viperidae. They are in difference Genus' and species of course. BUt at the family level (one up from genus) they are the same.
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QUESTION: ....would that be like calling a car and a truck both vehicles?...but one is a truck and one is a car....I am thinking more of the fact that a timber rattler and a pygmy rattler etc..are rattlesnakes perse, but a copperhead (not having a rattler) would not be called a "rattlesnake"
You used the word family. The classification hierarchy goes: Domain, Kingdom, Phylum, Class, Order, Family, Genus, species. Rattlesnakes would be separated from copperheads at the Genus level. All rattlesnakes are of the Genus Crotalus-the types of rattlesnakes are separated from there. For instance an Eastern Diamondback's scientific name is Crotalus adamanteus.
Viperidae refers to the fact that it's members are pit vipers. SO, if your question is: are copperheads rattlesnakes? The answer is no they are not. But, you asked if they are in the same family, so yes they are both pit vipers.
As to your car analogy. Vechicle would be the family level. Ford would be the Genus. F150 would be the species.