Joined in 2023 
82 
63 About this deal
Submersible vehicles also offer a unique window on jelly behavior and ecology. “One of the advantages of working on jellies is that they’re blind and deaf,” Robison says. “They don't seem to mind at all when we fly up to them and zoom in with our lights and cameras. We can make good observations of the interactions of jellies with one another, their prey, and their predators, without disturbing them.” And the jellies themselves, being transparent, offer an additional window onto their lives. “Who eats whom that’s easy to see with a transparent animal,” Robison says. “You don’t have to cut them open to find out what was for lunch.” Other organisms use their bioluminescence to fend off or dupe predators. The deep-sea shrimp ( Acanthephyra purpurea) vomit bioluminescent goop into the face of threatening diners, presumably either as a scare tactic or to create a distraction while the shrimp escapes. Other organisms seem to employ their bioluminescence as a kind of defensive burglar alarm: they light up to attract a second predator that will eat the first one (or to make the first predator think that a second one is coming, and so prompt it to leave).
All 200 species of jellyfish exhibit radial symmetry. This means that they have a distinct top and bottom, but do not have a left or right side as all of their appendages radiate outwards from a central point, rather like the spokes of a bicycle wheel. A Mediterranean jellyfish. Jellyfish Reproduction There’s a whole netherworld of the deep sea that we don’t see when we have our lights on,” says Kevin Raskoff, a scientist at California State University, Monterey Bay. “And that’s the natural light of the deep sea: bioluminescence.” Like most venomous animals, the jellyfish inject their venom to cause pain and irritation. Jellyfish venom contains a type of protein called a porin which is responsible for the pain caused by their sting. This protein is not only found in the venom of all jellyfish but also in their relatives, including corals and anemones. Many marine biologists suspect that much of the missing carbon has been in front of their noses the whole time in the transparent, gelatinous bodies of jellies. “Jellies are major players in the ocean’s carbon biomass,” Robison says. “They may be an overlooked part of the equation.” Jellyfish are one of the oldest animals on Earth and have changed very little from their prehistoric ancestors. These fascinating creatures have been studied by scientists for decades, increasing our understanding of the biological adaptations that have enabled them to persist in the world’s oceans for so long. Let’s take a closer look! Jellyfish StingThe larvae settle on the seafloor and are now known as polyps. The polyps then begin to bud asexually and produce medusae which then develop into adults. Other true jellyfish species belonging to other genera may spend their lives solely as polyps or medusae and not alternate between the two different life stages in the same way. Bioflourescent jellyfish: Getty Images UK. Close-up of purple jellyfish: Bruce H. Obison. Jellyfish with long tentacles: Natursports, Dreamstime. Yellow jellyfish: Tim Hester, Dreamstime. Map showing jellyfish distribution: National Geographic Maps. Not a lot is known about the ways that the various jellyfish species reproduce. The best-studied jellyfish belong to the genus Aurelia. These jellyfish have separate sexes and so the adults reproduce sexually. The males release their sperm through their mouths which then enter the surrounding water. These swim to the female and enter into her oral cavity where they are then able to reach the eggs. Once the eggs are fertilized, the fertilized eggs (zygotes) move into the oral arms where they spend some time developing and becoming larvae. Underwater, bioluminescence finds all manner of purpose. Some animals use it to attract mates. A male sea-firefly ( Vargula hilgendorfii) will squirt out a bright dot of light, zip upward, and then squirt another and another, essentially drawing an arrow that points out his whereabouts. Other creatures use bioluminescence to detect or lure prey. The viperfish ( Chauliodus sloani) dangles a luminescent lure in front of its mouth and then snaps up any creature that dares to investigate. Jellies are a completely surprising component of the deep-sea food web,” Robison says. “Our present understanding of where jellies fit into the way the world works is far from complete. But it’s very clear they are a significant part of deep-ocean communities.”
Many jellyfish species have the ability to produce their own light, in a process known as bioluminescence. This light is used primarily as a form of communication between animals and can be used for defense, offense, and intraspecific communication. The greatest diversity in jellyfish bioluminescence occurs in deeper water, where nearly every kind of jellyfish is luminescent and is mostly used in defense against predators. Jellyfish are known for their sting! These animals have tentacles that have tiny sting cells on them called cnidocytes. These cells have tiny structures inside them that are full of venom, called nematocysts. When something touches a jellyfish these nematocysts shoot out and can penetrate the skin of the animal. The jellies use this mechanism to help capture prey or as a defense mechanism when they feel threatened. Bioluminescence is light produced by a chemical process within a living organism. The glow occurs when a substance called luciferin reacts with oxygen. This releases energy, and light is emitted. An enzyme called luciferase facilitates the reaction. Sometimes luciferin and luciferase are bound together with oxygen into a single molecule, or photoprotein. When an ion such as calcium is present, an ensuing reaction emits light. To glow on a regular basis, an organism must continually bring fresh luciferin into its system. Some acquire it through their diet; others produce their own.Jellies were always relegated to an interesting but fringe category of strange, snotty animals in the water,” says Kevin Raskoff, a jelly scientist at the Monterey Bay Aquarium Research Institute. “But once we saw how prevalent they are and the diverse habitats they’re found in, it caused us to rethink their role in ecosystems as a whole.”
Jellies may also be important indicators of the health of ocean ecosystems. Some biologists have speculated that jelly populations thrive as increasing numbers of shrimps, fishes, and squids are harvested from the oceans, leaving behind vast amounts of uneaten small prey. A rise in jellies may signal drastic changes underway elsewhere in the ocean. “There is evidence,” Robison says. “But while it’s compelling evidence, it’s not yet convincing evidence.”Jellyfish have been around for millions of years, even before dinosaurs lived on the Earth. Pulsing along on our ocean currents, these jelly-like creatures can be found in waters both cold and warm, deep and shallow and along coastlines, too. Some jellyfish are clear, but others are vibrant colours of pink, yellow, blue and purple. They can be bioluminescent, too, which means they produce their own light! Humans can also be stung by jellyfish which can result in mild symptoms such as pain and blistering, to more serious symptoms including whole-body illness. In some cases, stings can even be life-threatening. Bioluminescence
Jellies are perfectly adapted to a three-dimensional watery habitat,” Robison says. “The fact that we see so many different kinds of them reflects the fact that they have a fundamentally successful body plan and way of making a living.” Almost from the moment George Matsumoto of the Monterey Bay Aquarium Research Institute first saw “Big Red,” he knew he was looking at a new species of jellyfish. It looked just plain bizarre: bulbous, dusky red, and huge, nearly one meter (about three feet) in diameter, with several fleshy arms instead of tentacles, like a balloon with greedy fingers. When Matsumoto and his coauthors, Kevin Raskoff of California State University and Dhugal Lindsay of the Japan Marine Science and Technology Center, described it in a scientific paper in 2003, they gave it a more official name: Tiburonia granrojo. Through the use of remotely operated submersible vehicles, or ROVs, scientists at MBARI have gained unprecedented access to the jellies’ realm. A scientific ROV is essentially a swimming robot outfitted with research equipment such as sampling containers, headlights, and high-resolution video cameras. While the vehicle dives deep into the cold undersea darkness, scientists sit comfortably aboard a ship on the sea surface, controlling the ROV movements remotely and watching its video feed on a bank of screens. Manned submersibles are also used in studying jellies, but an ROV, freed from its human occupant, can run longer without resurfacing and makes an excellent camera platform.
The Basics
Through genetic analysis, biologists are slowly gaining a better understanding of how and when the jellies evolved. Needless to say, fossils of jellies are few and far between. The evidence now suggests that jellies are an ancient life-form, hundreds of millions of years old, and probably predate most of the more familiar, complex animals. But many questions remain. For example, the comb jellies are typically classified into two types, those with tentacles and those without. Which type is older? Did the tentacleless kind appear first and the tentacled kind evolve later? Or did tentacles come first and then, in some comb jellies, disappear over time? Only further study and exploration will tell. What marine researchers know for certain is that the jellies they’ve discovered so far represent only a small fraction of what’s out there. In recent years we’ve learned that larvaceans account for a quarter to maybe a third of all the organic carbon that gets from the upper layers of the ocean in Monterey Bay, at least down to the deep-seafloor community,” Robison says. “They play a critical role in the transfer of energy from the sunlit layers to the deep seafloor.” The exploration is only beginning. The deep sea is an enormous place. The ocean surface itself occupies 71 percent of Earth’s surface area, and below every square foot of ocean surface are, in many cases, miles of water teeming with life much of it gooey and translucent. As available space goes, the deep sea is by far the largest ecosystem on Earth. And Monterey Bay, one of the best-explored deep-sea regions, represents only the smallest slice of the total. “We’ve still only explored a tiny fraction of the deep ocean,” Robison says, “so we know relatively little about all the different kinds of jellies that are out there.”
Great Deal 
New Comment