Jellies are trending 🙌🏼
Everyone is familiar with the basic idea of a jellyfish, but what do we mean when we use that term? Jellies in the class Scyphozoa include most of the species that people think of when hearing the word “jellyfish.” Their life cycles typically include a polyp stage, attached to the bottom, that produces baby medusae. When conditions are right, these babies can grow up to form vast blooms of adult jellies. These "true jellies" are commonly studied at the sea surface, but those living deep in the water column are less well known. Some deep-sea jellies defy what we imagine when we think of jellyfish—some with bells that can stretch up to a meter across, others with no tentacles at all. Many species of swimming jellies are actually in another group called the Hydromedusae. These jellies are often small and transparent, ranging from very few to numerous tentacles. Some Hydromedusans have tentacles that point ahead of them instead of trailing behind them as they swim. These species eat other gelatinous organisms rather than the crustaceans favored by many of their cousins. Even with all this dazzling diversity, we have yet to encounter many of the delicate drifters that live in the deepest waters of our vast ocean.