This video shows a snail with larvae of the Leucochloridium paradoxus worm in its body. Adults of this worm live in the bodies of birds, and the snail serves as an intermediate host for it.
- Leucochloridium penetrate into the horns of snails — through the skin you can see how they pulsate there in a characteristic way. This provokes birds, which are the next host in the worm's life cycle, to tear off and eat the affected tentacles, mistaking them for insects.
- Worm larvae also manipulate the behavior of snails. Is this due to the fact that snails have eyes at the ends of tentacles, or are there some less direct physiological mechanisms involved, but somehow Leucochloridium manages to change the snail's attitude to light.
- Negative phototaxis, which is the norm, gives way in infected individuals to the desire to get into the light. This leads them to open areas where, presumably, they are more likely to become prey for birds.