The worm has different sizes and shapes throughout its development. The eggs are brown and oval shaped. After hatching, the miracidia or first stage larvae are clear and elongate. After transformation, the miracidia become sack-like objects called sporocysts. The sporocysts cause the eyestalks of their snail hosts to pulsate yellow, green, and red. Some sporocysts then give rise to cercaria, or juveniles, which have tails and a more complex digestive tract. The cercaria have a lined excretory bladder which extends into their tails a bit and the tails also have finfolds on the top and bottom as well as setae on the sides. The cercaria also have two eyespots. Cercaria quickly become an encysted metacercaria from which emerge the adults. The adults are spined, long, dorsally flattened, and have suckers for attachment within their definitive hosts.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
- Fried, B., T. Graczyk. 1997. Advances in Trematode Biology. Boca Raton, FL: CRC Press.
- Roberts, L., J. Janovy Jr.. 2000. Foundations of Parasitology 6th ed.. Boston: McGraw-Hill.