Beroe cucumis has a transparent, sac-like body, often somewhat compressed, and reaches a maximum length of about 15 cm (6 in). The wide mouth is at one end. The body has eight longitudinal rows of cilia that extend from the aboral end (opposite end to the mouth), three quarters of the way along the animal. The cilia are arranged on short transverse plates and beat in synchrony to propel the animal through the water, giving a shimmering effect. The general body colour is pink, especially along the rows of cilia, and the plates are bioluminescent. There is a figure of eight shaped ring of small papillae around the aboral tip. Gastrovascular channels extend from the stomach through the body wall beneath the rows of cilia, and these have short side branches, which distinguishes Beroe cucumis from the otherwise similar Beroe gracilis. Juveniles of the two species are indistinguishable. The comb jelly Mnemiopsis leidyi is an invasive species originally native to the western Atlantic coastal waters that was introduced into the Black Sea in the 1980s, with deleterious results to the ecosystem. Since then it has spread to the Caspian Sea, the North Sea and the Baltic Sea. In the Black Sea, some measure of control was achieved when another predatory comb jelly, Beroe ovata, was introduced. Learn more about Comb Jelly