Cephalopyge trematoides (Chun, 1889)
The body is long and laterally compressed, it is colourless and transparent so that the internal organs are seen through the body wall. The body wall is covered with glandular cells, forming opaque bands especially along the dorsal and ventral body margins. The two tentacles are long. The foot is located anteriorly, below the posterior region of the pharynx and is capable of considerable contraction and expansion. It lives in the pleuston in the warmer waters of all oceans and is a carnivorous species (Cephalopyge trematoides).
The animals have a long and laterally compressed body. The tail is slightly truncated. Colourless and transparent. The internal organs which are mostly opaque except for the pinkish to reddish-brown intestine and gonads, seen through the body wall. The body wall is covered with glandular cells, forming opaque bands especially along the dorsal and ventral body margins. After preservation the longitudinal muscles running nearly along the entire body are visible. The two tentacles are long, smooth and erect. At the dorsal side of the head, a cephalic disc is found. The mouth is a slit with small lips. A longitudinal groove runs from the base of the mouth ventrally and posteriorly to the foot. The foot is located anteriorly, below the posterior region of the pharynx and is capable of considerable contraction and expansion. Jaws are present, the radula formula is 1-1-1, there are 12 transverse rows.
Body length up to 25 mm, and body height up to 3.5.
A special description is not available.
This species is a protandric hermaphrodite.
This species is supposed to be carnivorous; good swimmer, that lives near the sea surface.
It occurs in all oceans, including the Mediterranean, in warm and occasionally in temperate waters, see the Cephalopyge trematoides map.
Phyllirhoe trematoides Chun, 1889: 547.
Type locality: Canary Islands.