Since thelevels of PUFA in sub-littoral sediments are typically
low, the diet of harpactacoid copepods would inevitably
be depleted in PUFA, and it is therefore plausible that
evolutionary pressures have led to harpactacoid copepods
developing the capability to synthesize some
PUFA. It is important to appreciate that many organisms,
including humans and fish, do possess genes that
code for PUFA desaturases, but that these genes are
either not expressed or operate inefficiently, possibly
because the diets in question are generally replete in
these compounds (Tocher et al., 1998).