Alkenone

Alkenones are long-chain unsaturated methyl and ethyl n-ketones produced by a few phytoplankton species of the class Prymnesiophyceae.

[2] Uniquely for biolipids, alkenones have a spacing of five methylene groups between double bonds, which are of the less common E configuration.

[3][4] Alkenones were first described in ocean sediments recovered from Walvis Ridge[5] and then shortly afterwards in cultures of the marine coccolithophore Gephyrocapsa huxleyi.

Alkenone-producing species respond to changes in their environment — including to changes in water temperature — by altering the relative proportions of the different alkenones they produce.

This means that the relative degree of unsaturation of alkenones can be used to estimate the temperature of the water in which the alkenone-producing organisms grew.