![]() By analyzing the molecules and proteins in the spheres, Ames' team confirmed that the spheres came from the jellyfish and were dispersed from spoon-shaped pads on the animals' arms.Ĭlose-up of a cassiosome (Image credit: Allen Collins and Cheryl Ames) A minefield of mucus and toxic "bombs" The team uncovered one stray study from 1908 that mentioned the strange spheres, but those researchers had wrongly identified the structures as parasites of the jellyfish. "None of us could figure out immediately what they were." "We were really kind of in awe and shock, and saying, 'What are these? Has anyone seen these?'" Ames said. They spotted tiny, jelly-filled spheres floating within the fluid that appeared to be packed with cells and algae. To find out if these oddball jellies were the culprit, the researchers looked at samples of the jellies' mucus under high-resolution microscopes. With the mystery still unsolved, the scientists realized that, whenever they were stung, they were swimming near upside-down jellyfish at low tide, while the jellies pumped out murky clouds of mucus. Related: Dangers in the deep: 10 scariest sea creatures But researchers have visited the habitat so many times and never seen the adult stage of that hypothetical larval jelly, she added. Another theory posited that jellyfish still in their larval stage (and thus microscopic) might float through the water and sting people. ![]() "We initially thought that there would maybe be some tentacle bits from other jellyfish" floating through the water, perhaps detached during a massive spawning event, as can happen, Ames said. None of the proposed explanations held up to scrutiny. Sea lice are parasites that prey on fish, but the term serves as a colloquial "catchall" for anything that causes water to sting, Ames said. We conclude that the specificity in symbioses between marine invertebrates and dinoflagellates appears to be regulated by processes that occur after potential algal symbionts are phagocytosed.Those familiar with stinging water may have heard of so-called sea lice, creatures often blamed for the painful sensation associated with upside-down jellies. Neither was there any correlation between phagocytosis and persistence. ![]() No correlation was observed between the surface electrical charge on algae and their phagocytosis by host endodermal cells. Phagocytosis of algae and carmine particles was found to be a competitive process in scyphistomae of C. The endodermal cells of the scyphistomae of the non-symbiotic medusa Aurelia aurita also phagocytosed freshly isolated algae, but did not phagocytose cultured algae. Freshly isolated algae treated with reagents that removed the host membrane were phagocytosed at low rates. All cultured algae, even those that proliferate in host tissues, were phagocytosed at very low or undetectable rates. ![]() The rates of phagocytosis of such cells were high, and were directly correlated with the presence of a membrane, thought to be the host cell vacuolar membrane that surrounds the freshly isolated algae. All strains of the symbiotic dinoflagellate Symbiodinium microadriaticum were phagocytosed by the endodermal cells of the scyphistomae when presented to them as cells freshly isolated from their respective hosts. We have investigated whether interactions between cell-surface macro-molecules play a role in cellular recognition leading to specificity in the establishment of intracellular symbiosis between dinoflagellates and the polyp (scyphistoma) stage of the jellyfish Cassiopeia xamachana.
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