As If Light Could Ever Be the Answer (amber snail to the green-banded broodsac)

The green-banded broodsac is a behavior-altering flatworm that causes the snail to seek the light it usually avoids. The flatworm occupies the snail’s eye stalk and pulsates, mimicking the appearance of a caterpillar, so a nearby bird—the definitive host—might be tricked into eating the parasite. You prod me, shrinking, into the light. My tender eye…