Jellyfish stings are relatively common problems for people swimming, wading or diving in seawaters. The jellyfish capture zooplankton by stunning them with stinging cells (nematocysts), located in their oral arms and using a mucus they release. They then suck in the mucus filled with prey—such as shrimp and other plankton—using their frilly feeding structures to consume the meal. Cassiopea can take up the algae from the water, which is necessary for development. "However, when scientists studied the pure venom, extracted from the stinging capsules—nematocysts—they found that the toxins can destroy cells. Cassiopea is a family of jellyfish commonly referred to as 'upside down jellyfish'. Some jellyfish stings may cause more whole-body (systemic) illness. Study coauthor Allen Collins, a NOAA invertebrate zoologist, is no stranger to this stinging sensation. The sting is from a box jellyfish. The scientists say that this stinging strategy has never been identified before. "Cassiopea, like its common name upside-down jellyfish suggests, is found facing upward on the bottom of shallow coastal waters in bays, mangroves and lagoons—pulsing rhythmically in groups of hundreds to thousands of individuals," Ames said. Cassiopea (upside-down jellyfish) is a genus of true jellyfish and the only members of the family Cassiopeia. Jellyfish are transparent and made up of 95 percent water, so you’d think there isn’t much to them. Vote Now! When an unlucky predator comes too close to Cassiopea xamachana it sets off the cnidocil and nematocysts are released into the surrounding water. But now, a study published in the journal Communications Biology, reveals what may be the real culprit. While Cassiopea doesn’t have long trailing tentacles, it does have short, frilly arms that pulsate in the water. The sting covers more than half an arm or leg. They have a mild sting bean since they are primarily photosynthetic, but sensitive individuals may have a stronger reaction. Cassiosomes may be a way for the algae to get out and get around.”. What to Do if You Get Stung By a Jellyfish. When these jellyfish feed they release clouds of mucus which they use to catch prey like a net. 1. Located on their tentacles, jellyfish's stinging cells. "We know there's a really tight symbiosis there,” Collins says. "Additionally, Cassiopea generated stinging water, which we now know is caused by the cassiosomes in the jellyfish mucus, causes a sensation that is itchy-to-burning and—depending on the person—can cause enough discomfort to make them to want to get out of the water. But in coastal mangroves and other subtropical ecosystems, snorklers and swimmers have long reported a similar sensation without ever coming in contact with a jellyfish. Terms of Use The medusa usually lives upside-down on the bottom, which has earned them the common name. In a study published in Communications Biology, researchers found a jellyfish species called Cassiopea xamachana which when triggered will release tiny balls of cells that swim around the jellyfish stinging everything in their path. Their sting can have different effects on humans, depending on sensitivity to the toxin: rash, vomiting, and so on. "Like all jellyfish, Cassiopea is a carnivore, but different from many jellyfish, it also has single-cell algae living in its cells. These gelatinous critters like to hang out towards the sea floor in shallow calm bays and channels. This team of researchers have uncovered an entirely unknown mechanism of stings, as cassiosomes have since been found in other related jellyfish species and could be even more widespread. The jellyfish can capture its prey through the use of nematocysts contained within their tentacles (Costley and Fitt, 1998). “I had always assumed that it was well explained somewhere in the literature and that we just hadn’t come across it yet,” Collins says. Using advanced microscopic techniques they were able to identify tiny masses of stinging cells called "cassiosomes," which the jellyfish use almost like "mobile grenades" to trap and kill prey.