Adult Schistosomes, unlike other trematodes, are long and cylindrical worms and are sexually dimorphic. The male<unk>  is approximately 1 cm long (0.6–1.1 cm) and is 0.1 cm wide. It is white, and it has a funnel-shaped oral sucker at its anterior end followed by a second pediculated ventral sucker. The external part of the worm is composed of a double bilayer, which is continuously renewed as the outer layer, known as the membranocalyx, and is shed continuously. The tegument bears a large number of<unk> all tubercules. The suckers have<unk> all thorns in their inner part as well as in the buttons around them. The male genital apparatus is composed of 6 to 9 testicular masses, situated dorsally. There is one deferent canal beginning at each testicle, which is connected to a single deferent that dilates into a reservatory, the seminal vesicle, located at the beginning of the gynaecophoric canal. The copula happens through the coaptation of the male and female genital orifices. The female has a cylindrical body, longer and thinner than the male's (1.2 to 1.6 cm long by 0.016 cm wide). It has the general appearance of a roundworm. The female parasite is darker, and it looks gray. The darker color is due to the presence of a pigment (hemozoin) in its digestive tube. This pigment is derived from the digestion of blood. The ovary is elongated and slightly lobulated and is located on the anterior half of the body. A short oviduct conducts to the ootype, which continues with the uterine tube. In this tube it is possible to find 1 to 2 eggs (rarely 3 to 4) but only 1 egg is observed in the ootype at any one time. The genital pore opens ventrally. The posterior two-thirds of the body contain the viteline glands and their winding canal, which unites with the oviduct a little before it reaches the ootype. The digestive tube begins at the anterior extremity of the worm, at the bottom of the oral sucker. The digestive tube is composed of an esophagus, which divides in two branches (right and left) and that reunite in a single cecum. The intestines end blindly, meaning that there is no anus. Sex<unk>  and other schistosomes are the only flukes or flatworms that exhibit sex separation as they exist as male and female individuals as in dioecious animals. However, they are not truly dioecious since the adults live in permanent male-female pairs, a condition called in copula, although they can be physically separated. But isolated females cannot grow into sexually-mature adults. In copula starts in the liver only after which they can move to their final habitation, the inferior mesenteric veins. Individual females cannot enter the mesenteric veins. Sex organs, the gonads, are also incompletely separated and are interdependent between sexes. Egg-making organ, the vitelline gland in female does not develop in the absence of male. Male gametes, spermatozoa, are present in the oviduct. In males, there are rudimentary ovaries, oviduct, and oocytes (developing female gametes), as well as vitelline cells. Males also possess the genes for hermaphroditism in flukes. Thus, they are technically hermaphrodites. Egg The eggs are oval-shaped, measuring 115–175 µm long and 45–47 µm wide, and ~150 µm diameter on average. They have pointed spines towards the broader base on one side, i.e. lateral spines. This is an important diagnostic tool because co-infection with S. haematobium (having a terminal-spined eggs) is common, and they are hard to distinguish. When the eggs are released into the water, a lot of them are immature and unfertilised so that they do not hatch. When the eggs are larger than 160 µm in diameter, they also fail to hatch. Larva The miracidium (from the Greek word μειράκιον, meirakion, meaning youth) is pear-shaped, and gradually elongates as it ages. It measures about 136 μm long and 55 μm wide. The body is covered by anucleate epidermal plates separated by epidermal ridges. The epidermal cells give off numerous hair-like cilia on the body surface. There are 17–22 epidermal cells. Epidermal plate is absent only at the extreme anterior called apical papilla, or terebratorium, which contains numerous sensory organelles. Its internal body is almost fully filled with glycogen particles and vesicles. The cercaria has a characteristic bifurcated tail, classically called furcae (Latin for fork); hence, the name (derived from a Greek word κέρκος, kerkos, meaning tail). The tail is highly flexible and its beating propels the cercaria in water. It is about 0.2 mm long and 47 μm wide, somewhat loosely attached to the main body. The body is pear-shaped and measures 0.24 mm in length and 0.1 mm in width. Its tegument is fully covered with spine. A conspicuous oral sucker is at the apex. As a non-feeding larva, there are no elaborate digestive organs, only oesophagus is distinct. There are three pairs of mucin glands connected to laterally to the oral sucker at the region of the ventral sucker.
Schistosoma mansoni
Schistosoma japonicum
Taenia asiatica
Schistosoma haematobium
Taenia solium
Echinostoma cinetorchis
Taenia saginata
Trichuris trichiura