Why is archaea called extremophiles?
Archaea are considered as different from other bacteria.
Their cell wall is different from that of bacteria.
Archaea are found in extreme conditions such as volcanic vents, subzero temperatures, and extremely high salt content. Normal bacteria can not survive in these extreme conditions. Hence the title extremophiles.
Extreme referes to extreme conditions such as high heat ,high salt , low temperatures. "philes " is from the Greek to love like a brother.
So extremophiles means to love extreme or harsh conditions.
Archaea probably don't "love" the extreme conditions but they are able to survive and thrive where other forms of bacteria cannot.