A sensory structure, the apical sense-organ, sits at the end opposite the mouth. The pattern of beating of pairs of comb row can then be modified based on stimuli from the balancer cilia to maintain proper vertical orientation or change swimming direction. Sensory information from a diffuse ectodermal nerve net can also influence comb row beating. Most ctenophores are capable of bioluminescence, which is quite faint and only visible in darkened conditions. The dim glow is typically confined to the digestive canals that underlie each of the comb rows.
Ctenophores are strictly carnivorous and prey on a variety of planktonic animals.
About 90 species inhabit all types of marine environments. Cydippid bodies are typically globular or pear-shaped. Lobate comb jellies typically have flattened oval-shaped bodies. Tentacles are present but much reduced in size compared to cydippids. Comb rows run along the aboral edge.