Ctenophores are bioluminescent, gelatinous organisms – also known as comb jellies. They swim by row-like motions with their “combs”, aligned in 8 rows around its body. They come in a variety of shapes and sizes, from a few millimeters to over one meter! Altough they look like jellyfish, ctenophores actually belong to an entirely different taxonomic group, and are not related to jellyfish at all. Some taxonomists actually believe that ctenophores were the first animals to exist – even before sponges, although this is still a debated topic.

Most ctenophores produce bioluminescense through their ciliated 8 rows of combs. In pictures and videos we often see ctenophores with a rainbow-like colour, this is not bioluminescense but rather the scattering of light producing a prism effect! The actual colour of ctenophore bioluminescense is blue/green.

Ctenophores are predators, hunting small copepods, fish and mollusc larvae, and krill, among other things. Predation tactics vary among the different ctenophore species, often specialized for capturing their specific prey. They usually catch their prey with long tentacles, covered in sticky cells that prey will get stuck to. After a prey is caught, the ctenophore will bring the tentacles with its prey towards it mouth, where it will be swallowed and digested.

Ctenophore photographed in the deep mesopelagic zone. (by Woods Hole Oceanographic Institute)

Previously, ctenophores have been regarded as dead-ends in the marine food web, due to consisting mainly of gelatinous matter with a high concentration of water. However, recent studies have shown that when abundant, organims can eat and digest them efficiently, being a proper diet for fish, jellyfish and turtles.

Excited about mesopelagic organisms? You can see more in our recent animated video, featuring 12 different animals!