ctenes

Ctenes are rows of fused cilia that function as combs on the bodies of ctenophores, commonly known as comb jellies. The term derives from Greek, reflecting the comb-like appearance of these structures. Each ctene consists of a comb plate that contains thousands of cilia, which beat in a coordinated fashion to propel the animal through water. The eight longitudinal ctenes are the most familiar arrangement in many species, though the exact number and pattern can vary among different ctenophore taxa.

The beating of the ctenses occurs in a metachronal wave, a synchronized sequence that produces locomotion with comparatively gentle propulsion and reduced turbulence. This coordinated movement also disperses light, giving the animal’s surface a shimmering, iridescent quality as light diffracts through the cilia. Because ctenses are a prominent and distinctive morphological feature, their presence, number, and arrangement are important for species identification and systematic classification within Ctenophora.

Variation among species includes differences in the number of ctene rows, their spacing, and their distribution along the body. In taxonomic keys, ctene pattern is used together with other characters such as tentacle presence (in many groups) and body shape to distinguish families and genera. Ctenses are a defining feature of the phylum and are central to discussions of ctenophore locomotion, ecology, and evolution.

See also: Ctenophora, comb jellies, metachronal rhythm.