The kingdom Crenarchaeota is now known to include archaea which inhabi
t a wide variety of low-temperature environments. We report here lipid
analyses of nonthermophilic crenarchaeotes, which revealed the presen
ce of cyclic and acyclic dibiphytanylglycerol tetraether lipids. Nonth
ermophilic crenarchaeotes appear to be a major biological source of te
traether lipids in marine planktonic environments.