Trematodes are flattened oval or worm-like animals, usually no more than a few centimetres in length, although species as small as 1 millimetre (0.039 in) (Monogenea) and as large as 7 centimetres (2.8 in) (Fasciolopsis) are known. Is a class within the phylum Platyhelminthes that contains two groups of parasitic flatworms, commonly referred to as flukes.
Trematodes are small parasitic flatworms that use vertebrates as their definitive host, and molluscs (usually freshwater snails or land snails) as their intermediate host. To accomplish this, they have several varied life cycle stages.  Most trematodes have complex life cycles, with larval stages parasitizing one or more species that are different from host of adults. Larval stages of some medically important species include miracidium, redia, cercaria, and metacercaria. Most trematodes are endoparasites. They include several parasites that have an enormous impact on human populations, such as human liver flukes and the blood flukes that cause schistosomiasis. Trematodes are flattened oval or worm-like animals, usually no more than a few centimetres in length, although species as small as 1 millimetre (0.039 in) (Monogenea) and as large as 7 centimetres (2.8 in) (Fasciolopsis) are known. A species that exemplifies the remarkable life history of the trematodes is the bird fluke, Leucochloridium paradoxum. The definitive hosts, in which the parasite reproduces, are various woodland birds, while the hosts in which the parasite multiplies (intermediate host) are various species of snail. The trematodes or flukes include 18,000 to 24,000 species, divided into two subclasses. Nearly all trematodes are parasites of mollusks and vertebrates. The smaller Aspidogastrea, comprising about 100 species, are obligate parasites of mollusks and may also infect turtles and fish, including cartilaginous fish. A species that exemplifies the remarkable life history of the trematodes is the bird fluke, Leucochloridium paradoxum. The definitive hosts, in which the parasite reproduces, are various woodland birds, while the hosts in which the parasite multiplies (intermediate host) are various species of snail. They are internal parasites of molluscs and vertebrates. Most trematodes have a complex life cycle with at least two hosts. The primary host, where the flukes sexually reproduce, is a vertebrate. The intermediate host, in which asexual reproduction occurs, is usually a snail. A species that exemplifies the remarkable life history of the trematodes is the bird fluke, Leucochloridium paradoxum. The definitive hosts, in which the parasite reproduces, are various woodland birds, while the hosts in which the parasite multiplies (intermediate host) are various species of snail. Trematoda-Flukes. Trematoda class or trematodes are commonly known as flukes. Flukes are flat worms. Parasitic flukes live in the intestine, tissue or in the blood. Their life cycle begins when molluscs such as snails get infected with fluke larvae. The first stage larvae are called miracidia.  © Albis Gabrielli/WHO. Foodborne trematode infections, or foodborne trematodiases, are a group of parasitic infections caused by trematodes (flatworms or “flukes”) that are acquired through ingestion of food contaminated with the larval stages of the parasite.  Background. Trematode infections occur worldwide. Trematodes, also called flukes, cause various clinical infections in humans. The parasites are so named because of their conspicuous suckers, the organs of attachment (trematos means pierced with holes). All the flukes that cause infections in humans belong to the group of digenetic trematodes. Important features exhibited by adult digenetic trematodes are summarized below (see Features of digenic trematodes). Trematode infections such as schistosomiasis have emerged as important tropical infections. Trematoda is a class within the phylum Platyhelminthes that contains two groups of parasitic flatworms, commonly referred to as flukes. The trematodes or flukes are estimated to include 18,000 to 24,000 species, and are divided into two subclasses. Nearly all trematodes are parasites of mollusks and vertebrates. Anatomy Trematodes are flattened oval or worm-like animals, usually no more than a few centimetres in length, although species as small as 1 millimetre (0.039 in) and as large as 7 centimetres (0.23 ft) are known. Varied trematodes, from 1911 Encyclopaedia Encyclopædia. Britannica trematodes are flattened oval or-worm like, animals usually no more than a few centimetres in, length although species as small as 1 (millimetre.0 039) (In) monogenea and as large as 7 (centimetres.2 8) (In) fasciolopsis are. known A species that exemplifies the remarkable life history of the trematodes is the bird fluke, Leucochloridium paradoxum. The definitive hosts, in which the parasite reproduces, are various woodland birds, while the hosts in which the parasite multiplies (intermediate host) are various species of snail.
https://en.wikipedia.org/wiki/Trematode_lifecycle_stages http://animaldiversity.org/accounts/Trematoda/ https://en.wikipedia.org/wiki/Trematoda https://en.wikipedia.org/wiki/Trematoda https://en.wikipedia.org/wiki/Trematoda http://www.parasitesinhumans.org/trematoda-flukes.html http://www.who.int/foodborne_trematode_infections/en/ http://emedicine.medscape.com/article/230112-overview http://www.parasitetesting.com/definition-of-flukes.cfm https://en.wikipedia.org/wiki/Trematoda
what are trematodes