Ctenophore

Ctenophores, or comb jellies, are similar to jellyfish, with soft gelatinous bodies. Unlike jellyfish, which use jet propulsion to move through the water, ctenophores swim by beating their "combs" - rows of tiny cilia (hair-like structures). They are poorly understood, being patchily distributed in the ocean and difficult to collect and study, as their gelatinous bodies are quite delicate. 

Photo Credit: Ctenophore by , 2006. https://en.wikipedia.org/wiki/Ctenophora#/media/File:Juvenile_Bolinopsis_cte. Licenced with Public Domain.