The pulsating, green broodsacs fill the eye stalks of the snail, thereby attracting predation by birds, the primary host.

The tentacle is swollen and the pulsating, colourful, banded broodsac visible inside mimics the appearance of an insect larva like a caterpillar.

Birds may also become infected by eating broodsacs that have spontaneously burst from the tentacle, surviving for an hour whilst they continue to pulsate.

This form has two suckers on the ventral side, which anchor it to the cloacal wall, and a smooth dorsal surface.

[12] The pulsations of the broodsacs typically vary from 40 to 75 times a minute depending on temperature, but they cease in the dark.

In one study of Succinea putris hosts, infected snails stayed in better lit places for longer, sat on higher vegetation, and were more mobile.

Leucochloridium paradoxum exhibits broodsacs that have green bands with dark brown and black spots, and with a dark-brown or reddish-brown tip.

Leucochloridium paradoxum was originally described based on its sporocyst stage, collected from an island in the river Elbe at Pillnitz, near Dresden, Germany.

[1] Other known locations are Poland, Belarus, the Saint Petersburg area of Russia, Denmark, Sweden, Norway, the Netherlands, the United Kingdom and Japan.