Leucochloridium paradoxum, The Green-Banded Broodsac

Identification

This parasitic flatworm results in banded, shifting color patterns in infected snails' eye stalks.

Life Cycle

Two-Host

Definitive host: Various bird species

Intermediate host: Terrestrial snails

Durable eggs remain in soil (or bird feces) and do not hatch until they are eaten by a snail. When an egg hatches in the snail gut, the miracidium inside migrates to snail tissues where it forms sporocysts. Sporocysts then produce cercariae, free-swimming larvae, that then become infective metacercariae. Meanwhile, sporocysts extend up through the snail and form a pulsing, colorful pattern that attracts birds. When eaten, metacercariae form adult parasites that develop and sexually reproduce in the gut and cloaca of birds before being deposited in the soil through feces.

http://www.biology.ualberta.ca/parasites/ParPub/lifecycl/text/strig04t.htm

Host Information

Snail intermediate hosts are ectothermic with high heat and low cold tolerance, which means optimal conditions for them, and thus parasite transmission, are warm and wet. Fortunately for L. paradoxum (and explanatory of the evolution of this life cycle), the diet of snails of the genus succinea includes bird feces, so snails have frequent encounters with potential reservoirs of L. paradoxum eggs.

Distribution

The parasite has been reported in Germany, Norway, and Poland, and are most often found in moist areas in forests alongside their definitive and intermediate hosts.

https://en.linkfang.org/wiki/Leucochloridium_paradoxum