Best Jellyfish

Turritopsis dohrnii is a very small hydrozoan jellyfish associated originally with the Mediterranean but now recorded in several marine regions. Under stress or after reproduction, its medusa can transform its specialized cells and return to a colony-forming polyp stage, effectively restarting the l...

Chironex fleckeri is a large box jellyfish found in coastal waters of northern Australia and parts of the Indo-Pacific. Its nearly transparent, box-shaped bell bears four clusters of tentacles containing nematocysts that inject potent venom, which can cause extreme pain, cardiac arrest, and death in...

The Portuguese man o' war, Physalia physalis, is a pelagic hydrozoan composed of specialized individuals functioning together as a colony, rather than a single jellyfish. Its gas-filled float remains at the sea surface and acts like a sail, while long tentacles trail beneath it to capture fish and o...

The lion's mane jellyfish, Cyanea capillata, is a cold-water scyphozoan found mainly in northern parts of the Atlantic and Pacific oceans and in Arctic waters. It has a broad bell and numerous clusters of long, trailing tentacles armed with stinging cells used to capture small fish and other prey. E...

Carukia barnesi is a tiny cubozoan of Australian waters, roughly 2 cm in bell diameter, responsible for Irukandji syndrome, a severe systemic envenomation first clinically described by Jack Barnes in 1964.

The giant phantom jellyfish, Stygiomedusa gigantea, is a rarely observed deep-sea scyphozoan found in oceans around the world. It has a bell that can approach one meter across and four broad, ribbonlike oral arms that may extend several meters, rather than the numerous slender tentacles associated w...

Aurelia aurita, commonly called the moon jellyfish, is a translucent scyphozoan jellyfish recognizable by four horseshoe shaped gonads visible through its bell. It feeds mainly on small plankton captured with mucus and cilia and occurs in coastal and sheltered waters across a broad geographic range,...

Aurelia aurita, commonly called the moon jellyfish, is a translucent scyphozoan occurring in temperate and tropical coastal waters. Adults are commonly recognized by four horseshoe-shaped gonads visible through the bell, although identification within the genus Aurelia can require genetic analysis....

Nemopilema nomurai is one of the largest jellyfish in the world, with bells regularly exceeding 2 metres in diameter and weights over 200 kg, and its blooms in the Sea of Japan have repeatedly damaged Japanese fishing nets.

The warty comb jelly, Mnemiopsis leidyi, is a transparent marine ctenophore native to Atlantic coastal waters of the Americas. It moves using rows of beating cilia and feeds on zooplankton, fish eggs, and larvae; despite its jellylike body, it is not a true jellyfish. Introduced into the Black Sea b...

Deepstaria enigmatica is a deep-sea jellyfish recognized by its unusually thin, broad bell, which can fold into a baglike form around prey. The species was formally described in 1967 and belongs to the family Ulmaridae within the true jellyfishes, or Scyphozoa. Because it inhabits deep pelagic water...

Mastigias papua inhabits coastal lagoons across the Indo-Pacific and is famous for the landlocked populations in Jellyfish Lake, Palau, which lost their stinging ability due to predator-free isolation.

Atolla wyvillei is a deep-sea scyphozoan jellyfish in the order Coronatae, recorded from oceans around the world. Its bell is typically dark red, and it can produce a conspicuous pattern of bioluminescent flashes when attacked. This display has been described as a “burglar alarm” because the light m...

Stomolophus nomurai, commonly called Nomura's jellyfish, is a very large rhizostome jellyfish found in waters of East Asia, including the Yellow Sea, East China Sea, and Sea of Japan. Mature individuals can develop bells approaching or exceeding two meters in diameter and weigh well over 100 kilogra...

The Pacific sea nettle, Chrysaora fuscescens, is a large scyphozoan jellyfish native to the northeastern Pacific Ocean. It has a golden-brown or amber bell with pale radial markings and long oral arms and tentacles equipped with stinging cells used to capture prey. The species feeds mainly on zoopla...

The bloodbelly comb jelly, Lampocteis cruentiventer, is a deep-sea ctenophore known from the Pacific Ocean and formally described in 2001. Its dark red stomach helps conceal flashes produced by bioluminescent prey, because red wavelengths penetrate poorly in the deep sea. Despite its common name and...

The bluebottle, commonly identified as Physalia utriculus in Indo-Pacific waters, is a colonial hydrozoan rather than a true jellyfish. Its visible body is a gas-filled float, while specialized individuals within the colony perform feeding, defense, and reproduction. Long tentacles carry stinging ce...

Cassiopea xamachana is a species of upside-down jellyfish found in shallow tropical waters of the western Atlantic, including the Caribbean. It commonly rests bell-down on sandy or muddy bottoms in mangroves and lagoons, positioning its branching oral arms toward sunlight. Photosynthetic dinoflagell...

The mauve stinger, Pelagia noctiluca, is a pelagic jellyfish in the class Scyphozoa, widely recorded in the Mediterranean Sea and adjoining Atlantic waters. Its bell and tentacles bear stinging cells that capture prey and can produce painful skin reactions in swimmers. The species is bioluminescent,...

The black sea nettle, Chrysaora achlyos, is a large scyphozoan jellyfish found in the eastern Pacific, particularly in coastal waters off California and Baja California. It has a dark purple to nearly black bell, pale oral arms, and long trailing tentacles equipped with stinging cells. The species w...

Cotylorhiza tuberculata is a scyphozoan jellyfish native to the Mediterranean Sea and nearby waters. Its broad yellowish bell has a raised orange or brown center, producing the resemblance that gives the species its common name, fried egg jellyfish. It has branching oral arms rather than long margin...

Halitrephes maasi is a deep-sea hydromedusa in the family Halicreatidae, known from the open ocean at substantial depths. Remotely operated vehicles have recorded specimens whose radial canals reflect artificial light in vivid colors, producing a wheel-like appearance sometimes described as biolumin...

Tripedalia cystophora is a small species of box jellyfish found in shallow tropical mangrove habitats, particularly in the Caribbean region. Like other cubozoans, it has four sensory structures called rhopalia; together these carry 24 eyes of several types, including camera-like eyes with lenses. Re...

The flower hat jellyfish, Olindias formosus, is a hydrozoan medusa found in coastal waters of the western Pacific, particularly around Japan. Its translucent bell bears radiating colored bands, while numerous tentacles curl upward when they are not extended, producing its flower-like appearance. The...

The purple-striped jellyfish, Chrysaora colorata, is a scyphozoan jellyfish found in the eastern Pacific Ocean, especially in waters off California. Adults are recognized by dark purple radial stripes on a pale bell and by long tentacles and folded oral arms that trail beneath the body. It captures...

Alatina alata is a species of box jellyfish in the class Cubozoa, recorded from warm marine waters in several tropical and subtropical regions. It has a translucent, box-shaped bell and four muscular pedal structures from which its tentacles extend. The species is venomous and has been associated wi...

Malo kingi is a very small box jellyfish in the class Cubozoa and one of the organisms associated with Irukandji syndrome. It was formally described in 2007 from specimens collected in Queensland, Australia, and was named for Robert King, a tourist who died in 2002 after being stung near Port Dougla...

The barrel jellyfish, Rhizostoma pulmo, is a large scyphozoan jellyfish found in the Mediterranean Sea and the northeastern Atlantic Ocean. Its firm, dome-shaped bell can reach about 90 centimeters in diameter, although most individuals are smaller, and its eight thick oral arms lack the long margin...

Turritopsis nutricula is a small hydrozoan jellyfish originally described from the western Atlantic. It has often been associated in popular accounts with the ability to return from the adult medusa stage to a polyp-like juvenile state through cellular transformation, but much of the research behind...