- Body is flattened unsegmented, except female schistosomes (cylindrical).
- No body cavity.
- Organs of fixation in the form of suckers (oral, ventral).
- Hermaphrodites except schistosomes.
- All Trematodes need a snail intermediate host, so part of the life cycle occurs in water.
Digestive system:
- Incomplete digestive tract without anus
- Mouth, surrounded by oral sucker, leads to oesophagus that bifurcates in front of ventral sucker into two intestinal caeca.
- Caeca may be simple or branched.
Genital system:
- Hermaphrodites except Schistosomes.
- Male organs :
Two testes (TE) each gives a vas efferans (VE) that unit to give vas deferens (VD) that passes through a sac called cirrus sac (CS). Vas deferens ends by cirrus (CI) that opens in common genital atrium (GP).
- Female organs :
Single ovary (OV) leading to an oviduct that receives canal from swelling (seminal receptacle where sperms are stored) and common vitelline duct (D) receiving secretions of vitelline glands (VI). Oviduct opens in the ootype (OT). From ootype starts a coiled uterus (UT) that opens in common genital pore (GP).
Fertilization in trematodes:
- Self-fertilization.
- Cross-fertilization Follow Us
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