Beroidae - Comb Jellies (Ctenophores)

Comb jellies are members of the phylum Ctenophora, pronounced "ten-o-for-a" (the "C" is silent). They are free-floating marine organisms that have roundish bodies made up of gelatinous tissue that contain 95% water. There is no head or tail, but there is a mouth and an anus. Instead of a brain, they have a network of nerves beneath the skin. What sets comb jellies apart from real jellies are the eight rows or sets of cilia that line the body. The cilia are their main mode of transportation. Some comb jellies have two retractable tentacles, but the tentacles to not have stinging cells. Comb jellies can range in size from several millimeters to 1.5 m (59 in). All are carnivorous and some can swallow organisms larger than themselves. Some (like Beroe species) eat only other comb jellies. They are hermaphroditic, possessing both male and females sexual organs, but their reproduction is sexual.

Most comb jellies give off bioluminescence, especially when disturbed. If you've ever seen the waves glow on the beach at night, it is probably due to a swarm of comb jellies.