Jonathan Cohen's photos with the keyword: jellyfish

Not all jellies sting, but the sea nettle does. It hunts tiny drifting animals by trailing its long tentacles and frilly mouth-arms, all covered with stinging cells. When the tentacles touch prey, the stinging cells paralyze it and stick tight. From there, the prey is moved to the mouth-arms and finally to the mouth, where it’s digested.

Phacellophora camtschatica, known as the fried egg jellyfish or egg-yolk jellyfish, is a very large jellyfish, with a bell up to 60 cm (2 ft) in diameter and sixteen clusters of up to a few dozen tentacles, each up to 6 metres (20 ft) long. Like a large bird egg cracked and poured into the water, that three-foot, translucent bell is yolk-yellow at the center, with hundreds of tentacles clustered around the margin. The egg-yolk jelly is one of the larger species of jellies commonly found in Monterey Bay. This massive jelly usually drifts motionless or moves with gentle pulsing. Acting like an underwater spider web with a mild sting, an egg-yolk jelly captures other jellies that swim into its mass of tentacles. For their part, many animals rely on egg-yolk jellies and other gelatinous creatures for food, including sea turtles, at least 50 species of fishes (like the ocean sunfish) and marine birds (like the northern fulmar). Because the sting of this jellyfish is so weak, many small crustaceans, including larval crabs (Cancer gracilis) and Amphipoda, regularly hitchhike inside and on top of its bell and even steal food from its oral arms and tentacles. Young jack fish often can be found swimming among their tentacles.

The ghostly moon jelly travels across the open sea. A moon jelly isn’t just a passive drifter – it can swim on its own too. It gently pulses to move within the currents, traveling up and down and back and forth to find food. These alien-looking creatures are named for their translucent, moonlike circular bells. Instead of long, trailing tentacles, moon jellies have a short, fine fringe (cilia) that sweeps food toward the mucous layer on the edges of the bells. Prey is stored in pouches until the oral arms pick it up and begin to digest it. The coloration of a moon jelly often changes depending on its diet. If the jelly feeds extensively on crustaceans, it turns pink or lavender. An orange tint hints that a jelly’s been feeding on brine shrimp. Scientists have studied the life cycle of this jelly extensively. They know the adult male moon jelly releases strands of sperm, which are ingested by female moon jellies. After fertilization, larvae settle on or near the seafloor and grow into polyps. Polyps alternate between feeding and reproductive stages for up to 25 years. In the reproductive phase, polyps launch buds of cloned juveniles, known as ephyrae, which grow into adult medusae.

The purple-striped jelly is a species of jellyfish that exists primarily off the coast of California in Monterey Bay. The bell (body) of the jellyfish is up to 70 cm (27.6 inches or 2.3 feet) in diameter, typically with a radial pattern of stripes. The tentacles vary with the age of the individual, consisting typically of eight marginal long dark arms, and four central frilly oral arms. It is closely studied by scientists due to not much being known about their eating habits. When it is extremely young, it has a pinkish color and its tentacles are long and dark maroon. At the adult stage the dark maroon color of the tentacles starts to fade and the purple appears as stripes on the bell. At a young age the adults' four frilly oral arms will become longer. When the jellyfish starts to get older the tentacles thicken and the purple stripes start to darken and the tentacles start to look pale, its oral arms like to disappear. They are known to feed on a variety of organisms including zooplankton, including copepods, larval fish, ctenophores, salps, other jellies, and fish eggs. When the prey touches a marginal tentacle of the jelly, stingers are immediately discharged to paralyze prey and marginal tentacle bends inward to the nearest oral arm. The oral arm is used to transport prey to the gastrovascular cavity and to catch motionless prey. The sting of this jellyfish is extremely painful to humans but is rare.

SONY DSC

SONY DSC

SONY DSC