Marine bacteria living in cold environments have special fatty acids that help them survive in low temperatures. Scientists studied 22 types of these bacteria and found that some have specific fatty acids like docosahexaenoic acid and eicosapentaenoic acid. Bacteria with docosahexaenoic acid grow best in very cold temperatures, while those with eicosapentaenoic acid prefer slightly warmer conditions. Bacteria without these special fatty acids can handle higher temperatures. This discovery suggests that these fatty acids help marine bacteria adapt to cold environments, and can be used to tell apart bacteria that love the cold from those that can tolerate it.