CTENOPHORA

Common Names Ctenophores are often called “comb jellies,” “sea gooseberries,” “sea walnuts,” or “Venus’s girdles.” There are two classes in the phylum Ctenophora: Tentaculata, of which the most characteristic species is Hormimorpha plumosa Nuda, of which the most characteristic species is Beroe punctatus. The most commonly seen ctenophores are of the genus Pleurobrachia. There are about one hundred species of Ctenophora that have been discovered.

Characteristics All organisms in Ctenophora have comb rows that are actually large cilia used for transportation. These are the largest cilia any organism uses. Ctenophores lack the ability to sting and instead use tentacles covered by colloblasts . All ctenophores are bioluminescent, meaning they are capable of producing light. Some have the appearance of rainbow coloration. This is caused by the beating of their combs, causing the diffraction of light to form a rainbow. Classification is generally done through comparative morphology.

Characteristics (continued) Ctenophores have two digestive openings, but rarely use the anus for defecation Radial or Biradial symmetry and three germ layers (epidermis, gastrodermis, mesoglea if included) Mesoglea holds muscle cells and amoebacytes Digestive system consists of mouth, pharynx, and stomach with a canal system Have no CNS or brain, but a nerve net All Ctenophores have a distinct larval form before adulthood

Morphology Most ctenophores are round or spherical in body shape. They generally have two large tentacles and eight rows of comb plates. Their tentacles have the adhesive colloblasts to capture prey and they have a stomach, mouth, pharynx, and anal pores. They have a nerve network that is rather complex and an apical sense organ. All ctenophores are hermaphrodites and most reproduce sexually. They generally range in size from .6 cm to 30.5 cm.