At the end of the 19th century, it was believed that this organism (as well as some other creeping crests open at that time) was a special transitional form between intestinal and ciliary worms. Nevertheless, Kovalevsky himself was already ranked as a ctenophore, or Ctenophora, due to the structure of the intestinal canal, the presence of 2 retractable tentacles and the auditory organ, which is located in the center of the dorsal side at the end diametrically opposite the mouth opening, whereas the general form body, ciliary cover and lifestyle of the body brings it closer to flatworms, that is, Turbellaria. Another similar organism, also considered to be transitional in the 19th century, equipped with crest-like ciliary plates, was subsequently discovered by A. Korotnev in the Indian Ocean and named after Kovalevsky ( Ctenoplana Kowalevskii ).
In appearance, the whole plane resembles a planaria belonging to the ciliary worms, and is an oblong plate of irregular shapes (although in general the body shape is close to oval), flattened in the dorso-abdominal direction and equipped at both ends of the body with very long and branched tentacles, which can be of different colors: red, yellow, green, gray or whitish. The animal reaches a fairly small size - up to 7 centimeters in length and 5 in width. On the dorsal side, the color is usually grayish, on the abdominal side is white.
The tentacles of the cellophane can be completely drawn into the body and placed in special bottle-shaped vaginas, expanded at the base and opening outward by a narrowed neck. The tentacles are dense, that is, they do not have an internal cavity (as in most ctenophores), and consist of gelatinous matter and longitudinal muscle fibers, running along the entire trunk and small branches. The oral slit-like opening is placed in the middle of the abdominal side of the body, covered with cilia, on which the animal crawls, and leads to the intestine or digestive cavity, in which the central and peripheral parts are distinguished. The central part is monotonous, that is, in the form of a large cavity, flattened in the dorsal-abdominal direction, from which branching and anastomosing channels interconnecting along the outer edge of the lamellar body in a circular, or circular, branch out and in all directions, without special order, a channel equipped with small blind projections. From the central cavity, in which it is possible to notice a division into four bags, two processes of the intestine, ending in blind lunate lunar extensions, extend to the dorsal side of the body. Between these extensions, that is, on the dorsal side of the body, directly above the mouth opening, is placed a vial filled with liquid and containing a group of otoliths in constant tremulous movement, and representing the hearing organ. On the upper side of the body there are large numbers of so-called “papillae”. Rowing plates are developed only in the larval form of the animal, unlike other ctenophores, which are characteristic of them in adulthood.
The cellophane crawls on various objects, like planarians, with the entire abdominal side of its body, and the side that is directed forward is somewhat shorter; while crawling, the tentacles are pulled into the body, while in a calm state, when the coelope sits motionless, the tentacles are protruded outward.
