Comb Jelly

The comb jelly (Ctenophora) is a species of deep-sea Ctenophore that are related to jellyfish but are not actually jellyfish, like the Portuguese Man o’ War. They can be found in aphotic zones worldwide. Adult comb jellies range from a few millimeters to 1.5m in size. Comb jellies have egg-shaped bodies and a pair of retractable tentacles fringed with little tentacles that are covered with colloblasts which are sticky cells that capture prey.

The outer surface bears usually eight comb rows, called swimming-plates, which are used for swimming. The rows are oriented to run from near the mouth to the opposite end and are spaced more or less evenly around the body, although spacing patterns vary by species and in most species, the comb rows extend only part of the distance from the aboral pole towards the mouth. The “combs” run across each row and each consists of thousands of unusually long cilia, up to 2mm. These normally beat so that the propulsion stroke is away from the mouth, although they can also reverse direction. Hence ctenophores usually swim in the direction in which the mouth is eating, unlike jellyfish.

Comb jellies are strongly pigmented. Platyctenids generally live attached to other sea-bottom organisms and often have similar colors to these host organisms. The comb rows of most comb jellies produce a rainbow effect, which is not caused by bioluminescence but by the scattering of light as the combs move. Most species are also bioluminescent, but the light is usually blue or green.

If food is plentiful, they can eat 10 times their own weight per day. prey on jellyfish and incorporate their prey’s nematocysts (stinging cells) into their own tentacles instead of colloblasts. Ctenophores have been compared to spiders in their wide range of techniques from capturing prey – some hang motionless in the water using their tentacles as “webs”, some are ambush predators like Salticid jumping spiders, and some dangle a sticky droplet at the end of a fine thread, as bolas spiders do. According to Wikipedia, “members of the cydippid genus Pleurobrachia and the lobate Bolinopsis often reach high population densities at the same place and time because they specialize in different types of prey: Pleurobrachia’s long tentacles mainly capture relatively strong swimmers such as adult copepods, while Bolinopsis generally feeds on smaller, weaker swimmers such as rotifers and mollusc and crustacean larvae.”

 

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