Dugesia izuensis

Dugesia species have an elongated body with a slightly triangle-shaped head. They often have grey, brown, or black dorsal color, whereas the ventral surface is usually paler. These animals have a couple of eyes constituted by a multicellular pigmented cup with many retinal cells to detect the amount of light in the nearby environment. Sometimes they present supernumerary eyes. At the anterior part of the body, behind the eye level, they have a pair of structures called auricles that give the triangle look to the 'head' and allow them to detect the intensity of water current. These auricles are free of pigment and rhabdites. Each side of the anterior margin of the head has between 5 and 10 shallow sensory fossae, their number depending on the species or the individual. The sensory fossae and the auricle grooves are supplied with many nerve endings. The digestive system of Dugesia contains a central, non-pigmented tubular pharynx. Like the other triclads, the gut consists of three branches, one anterior and two posterior. Each branch consists of caeca, which deliver the nutrients to the body. The gut lacks a separate opening for waste excretion. The subepidermal musculature of Dugesia is divided into four layers. In Dugesia the ovaries are ventrally situated, they start just behind the brain, usually at the level of the fourth intestinal branch. …

Species of Dugesia are hermaphrodites. Many species can reproduce both sexually and asexually (by parthenogenesis or by fission).