Jellyfish are simple, successful and, occasionally, deadly creatures. The Australian box jellyfish has enough toxin in each of its tentacles to kill…Read More »
60 people. Some jellyfish create spectacular blooms when fields of polyps, their stationary life stage, simultaneously bud off into free-floating medusae. These blooms are blamed for the deaths of swimmers, clogged fishing nets and power plant intakes, and in certain parts of the world, like Japan, they appear to be on the rise.
But these problems are associated with only a subset of the creatures we call "jellyfish" – a catch all term for an amazingly diverse group of organisms. It includes corals, true jellies and others with stinging cells, as well as the stingless comb jellies, which swim using tiny hairs, called cilia.
What they also are is beautiful, as the following images attest.
Credit: NOAA/Monterey Bay Aquarium Research Institute
This giant red-hued jellyfish called Tiburonia granrojo was described by American and Japanese researchers in 2003. It grows up to 3.3 feet (1 meter) in…Read More »
diameter and lives at depths of 2,000 to 4,800 feet (650 to 1,500 meters) in the ocean. First seen during submarine dives in 1993, the jellyfish is distinct in that it uses four to seven fleshy arms to capture food, rather than fine tentacles like other jellyfish. Less «
3 of 18
Credit: Anders Garm
Tropical-dwelling box jellyfish have a cube-shaped body, and four different types of special-purpose eyes: The most primitive set detects only…Read More »
light levels, but another is more sophisticated and can detect the color and size of objects. The Australian box jellyfish is also deadly; each of its up to 60 tentacles carries enough toxin to kill 60 people.
The Australian spotted jellyfish, Phyllorhiza punctata, have invaded the Gulf of Mexico. With plenty of food, they grow as big as dinner plates and weigh…Read More »
up to 25 pounds (11 kilograms), although in their native waters they tend to be much smaller. They are not dangerous to humans, but pose a threat to shrimping and fishing industries. Less «
6 of 18
Oldest Known Jellyfish Fossils
Credit: Fossil photo by B. Lieberman. Cunina photo by K. Raskoff, copyright.
Fossil evidence of jellyfish dates back to the Cambrian Period, 500 million years ago. This fossil jellyfish shows similarity to the modern jellyfish,…Read More »
Cunina (right). It was one of four different types of jellyfish dated back to the Cambrian by researchers in 2007. These ancient jellyfish showed the same complexity as modern jellyfish, meaning they either developed rapidly 500 million years ago, or today’s varieties are much older. Less «
7 of 18
Credit: Shin-ichi Uye
The saucer-like Aurelia aurita, or moon jellyfish is carnivorous and feeds on small plankton organisms, such as mollusks, crustaceans and even ctenophores.…Read More »
It can be anywhere from two to 15.7 inches (five to 40 centimeters) in diameter and is found in mostly warm and tropical waters. Less «
8 of 18
Jellies from Above
Credit: Shin-ichi Uye
The moon jellyfish is common in many parts of the world, and it appears to have increased dramatically in Japanese waters in recent decades. Seen from…Read More »
a bird's eye view, a bloom of moon jellyfish appears as white swaths in a Japanese bay. In Japanese waters, its blooms have interfered with fishermen and power plants.
This image captures the courtship behavior of the box jellyfish Copula sivickisi. The male (top) and female (bottom) engage in a complex mating ritual…Read More »
unique among cnidarians (jellyfishes, hydroids, anemones, corals and their kin). Less «
12 of 18
The moon jellyfish is believed to have been introduced into many new environments by ships, when the jellyfish's stationary developmental stage, called…Read More »
a polyp, attached to their hulls or came in via the ballast water, which ships dump once they arrive at their destination. Less «
13 of 18
Credit: Lars Johan Hansson
The stealthy predator Mnemiopsis leidyi, also known as the sea walnut, uses tiny hairs, called cilia, to create a current which prey don't notice until…Read More »
they are sucked into its mouth region, surrounded by two large oral lobes. The sea walnut swims using fused cilia, which diffract light in many colors in this photo. Less «
14 of 18
A salp bloom off the coast of New Zealand. These bloblike creatures are not true jellyfish, but instead another group of free-swimming invertebrates. The…Read More »
5-inch (13-centimeter)-long , barrel-shaped organisms resemble streamlined jellyfish and live in mid-ocean waters where they filter the seawater for food particles. Less «
15 of 18
Credit: Dr. Steve Haddock
Here, a moon jellyfish bloom off the coast of Japan. Moon jellyfish (Aurelia aurita), are carnivorous and feed on the ocean's zooplankton (tiny floating animals).
16 of 18
Credit: Meaghan Schrandt
Fried Egg Jellyfish (Cotylrhiza) from Alicante, Spain, forms blooms along the Mediterranean coastline.
17 of 18
Credit: Dr. Shin-ichi Uye
Giant jellyfish (Nemopilema nomurai) clogging fishing nets in Japan. Also called Nomura's jellyfish, these gelatinous creatures can grow up to 6.7 feet (2 meters) in diameter.
18 of 18
Credit: Elizabeth Condon
Here a Portuguese Man-O-War (Physalia sp.), a species closely related to true jellyfish, is common in the world's oceans.
Science Newsletter: Subscribe
More from LiveScience
Wynne was a reporter at The Stamford Advocate. She has interned at Discover magazine and has freelanced for The New York Times and Scientific American's web site. She has a masters in journalism from Columbia University and a bachelor's degree in biology from the University of Utah.