Jellyfish snot can sting swimmers who never touch the animal
Swimmers who feel “stinging water” near mangrove forests may be getting zapped by jellyfish snot. A species known as the upside-down jellyfish (Cassiopea xamachana) can sting other creatures without ever making direct contact. Instead, the jellyfish releases mucus filled with clusters of stinging cells typically found on jellyfish tentacles, researchers report February 13 in Communications Biology. The study provides the first explanation for why handling or swimming near upside-down jellyfish can cause a prickling or burning sensation (SN: 9/1/15). The stinging cells are coated on tiny mobile blobs called cassiosomes within the mucus that “zoom around like a Roomba zapping brine shrimp” in a lab dish, says Cheryl Ames, a marine biologist at Tohoku University in Sendai, Japan. When brine shrimp came into contact with a cassiosome, the shrimp were quickly paralyzed and killed. C. xamachana is unusual among jellyfish in that the animal rests belly up in groups on the seafloor, which lets photosynthetic algae living in its tissues produce nutrients that benefit...