Commonly known as the “Arctic Comb Jelly” or “Sea Nut” Mertensia ovum is a species of cydippid ctenophore that occurs in Arctic and polar seas. Like many other ctenophores M. ovum is weakly bioluminescent and can produce a striking rainbow effect by beating their eight rows of cilia. Mertensia ovum is a carnivore and will feed on copepods and other small crustaceans that are snagged by its two sticky tentacles.
Mertensia ovum aka the Arctic comb jelly or Sea Nut, is a cydippidcomb jelly orctenophore first described as Beroe ovum by Johan Christian Fabricius in 1780. Unusually among ctenophores, which normally prefer warmer waters, it is found in the Arctic and adjacent polar seas, mostly in surface waters down to 50 metres (160 ft).