SCIENCE EIN S T ER S I IL E S M M S I E L I S R T E E S I N E S C C N I e E The J lly Do m e Jellies amaze us with their capacity to pulse through the sea, regenerate, and even glow! Scientists are discovering there See if you can are far more jellies in the world’s oceans than we once thought. Dive into the world of jellies to get a close-up look at these spot these jellies! astonishing animals. Pacific sea nettle Antarctic giant jellyfish (Chrysaora fuscescens) (Desmonema glaciale) With its golden red body This enormous jellyfish lives (or “bell”) trailing long tentacles only in the deep waters of the and ruffled oral-arms, the Pacific Antarctic Ocean. Its bell spans up sea nettle is stunning. Stinging to 4 feet (1.2 m) wide and its thick, cells line its tentacles and oral- cord-like tentacles stretch up to arms, and a single touch can paralyze 16 feet (4.9 m) long. Wide, flat oral- its prey. These jellyfish cannot see, and arms flow from the bell like curtains. use light-sensing organs to journey daily from the dark deep sea to well-lit waters near the surface. Crown Jellyfish Rhizostome Jellyfish (Cephea cephea) (Crambione mastigophora) “Spikes” spring from the crown The rhizostome jellyfish is jellyfish’s distinctive purplish found along many tropical bell, and a ring of oral-arms coastlines. These round, bluish form a shape like a cauliflower. jellyfish often wash ashore, Flowing tentacles under the carried by wind and tides. One of bell sting and capture prey. several edible species, in many These jellies grow extremely fast and places around the world, the rhizostome large. The bell of a typical adult is about jellyfish is a delicacy when dried and salted. two feet (60 cm) across. Lagoon Jelly Australian spotted jellyfish (Mastigias papua) (Phyllorhiza punctata) The lagoon jelly lives in shallow The Australian spotted jellyfish isolated waters like coastal lakes was once found only in the Pacific and lagoons. This spotted jelly is and Indian Oceans, but can now missing a “mouth” under its bell. be found in warm waters around Instead, it takes in food through the U.S. Today, this invasive species small openings in its oral-arms. It is is threatening ecosystems in the Gulf also host to algae called zooxanthallae. of California, Gulf of Mexico, and the The jelly rises to the surface each day. The sunlight helps Caribbean Sea. A bloom — a sudden rise in the the algae grow and the algae give the jelly energy in return. jellyfish population — can wipe out food for other species. April 10–May 26 | Milstein Hall of Ocean Life | Open during Museum hours Anatomy of a Jellyfish All About Jellies bell mouth What are Jellies? A “jelly” is a general term for any kind of transparent, gelatinous (or jellylike) animal that floats in the ocean. While different kinds may look alike, they are not all closely related. They belong to two different groups, cnidarians and ctenophores. Hundreds of jelly species live in oceans around the world, from shallow bays to the deep sea, and some even live in fresh water. The most common jellies are true jellyfish (a cnidarian) and comb jellies (a ctenophore). Jelly bodies are made of two transparent layers — an outer one for protection and an inner one for digesting food — with a watery gel in between. In fact, their bodies are more than 95% water. Most jellyfish have long stinging tentacles. They also haveoral-arms that help catch and eat food. Comb jellies have oval bodies lined with rows of flutteringcilia . Instead of stinging, they use their tentacles to pull prey into their large mouths. There’s not much more to a jelly — no bones, no head, no legs, and no brain! tentacles What makes jellies unique? oral-arms Jellies can do some amazing things. First, they move in fascinating ways. True jellyfish propel themselves by “pulsing” — pulling and pushing water in and out of their bodies. Comb jellies paddle through the water with tiny oar-like cilia. These animals are also Glossary extremely resilient: some jellies can regenerate, or regrow, lost bell: the umbrella-like body parts. And a few species have the ability to “age backwards.” body of a jellyfish These jellyfish can transform back into tiny polyps (the first stage of its life), which then grow into identical copies of the bioluminescence: light original adult. Finally, jellies can glow! Many species, especially produced by a chemical in the deep sea, are bioluminescent — they produce their own reaction within an light through a chemical reaction in their bodies. Other jellies organism are fluorescent — they absorb one color and emit another. This is how comb jellies generate glistening rainbow colors when bloom: a sudden rise in they swim. bioluminescent jellyfish a jelly population (Spacey Ctenophore) cilia: tiny, hair-like projections Cnidaria: a phylum of Why are Jellies important? marine animals with Jellies play a large role in the ocean ecosystem. Near the surface, most jellies eat tiny stinging cells, such as plankton that drift through the water. Deeper down, many graze on “marine snow” jellyfish, sea anemones, — bits of dead matter that drift down from the surface. Larger jellies eat fish, and corals crustaceans, and even other jellies. In turn, jellies are food for many species of fish, sea turtles, and marine birds. Jellies are also playing a part in medical advances. Ctenophora: a phylum of The genes responsible for regeneration in jellies may help scientists replace cells marine animals with sticky damaged by disease. Research on jellyfish venom could lead to new drugs. cells and rows of cilia; also Scientists are even using a protein for jelly fluorescence to tag cancer cells. known as comb jellies The cancer cells glow when exposed to light, making them easy to see and oral-arms: long appendages on a remove during surgery. jelly that move food to its mouth tentacles: long, thin parts that The Milstein Science Series is proudly sponsored by the Irma and Paul Milstein Family. hang from a jelly’s body Images provided by NatureFootage, Inc. | Jellyfish illustration by Eric Hamilton For more information, visit us at amnh.org/milstein.