Jelly Fish

Scientific Name: Rhizostomeae, Scyphozoa spp - undifferentiated
Australian Standard Fish Name:  Jellyfish
AQIS Code: JLY
Australian Species Code: 11 120000
Catch Method:  Wild caught

Other Names:
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About Jelly Fish
Jellyfish are free-swimming members of the phylum Cnidaria. They have several different basic morphologies that represent several different cnidarian classes including the Scyphozoa (about 200 species), Staurozoa (about 50 species), Cubozoa (about 20 species), and Hydrozoa (about 1000-1500 species that make jellyfish and many more that do not)[1][2]. The jellyfish in these groups are also called, respectively, scyphomedusae, stauromedusae, cubomedusae, and hydromedusae; "medusa" (plural "medusae") is another word for jellyfish. Jellyfish are found in every ocean, from the surface to the deep sea. Some hydrozoan jellyfish, or hydromedusae, are also found in fresh water. Most of the information about jellyfish that follows in this article is about scyphozoan jellyfish, or scyphomedusae. These are the big, often colorful, jellyfish that are common in coastal zones worldwide.

In its broadest sense, the term jellyfish is sometimes used also to refer to members of the phylum Ctenophora. Although not closely related to cnidarian jellyfish, ctenophores are also free-swimming planktonic carnivores, are also generally transparent or translucent, and occur in shallow to deep portions of all the world's oceans. Ctenophores move using eight rows of fused cilia that beat in metachronal waves that diffract light, so that they sparkle with all of the colors of the rainbow. The rest of this article deals only with jellyfish in the phylum Cnidaria.

Jellyfish are simple animals. Most, but not all of them, swim through the water (a few spend their lives attached to the bottom). Although there are many variations on this form, the body is composed of a bowl-like bell, also called the umbrella, which rhythmically opens and closes, by contracting muscles and then releasing the contraction, in order to swim. They may swim in any direction, but the closed end of the bell always leads if they are actively swimming. In different species, the bell can be hemispherical, even more fully closed, or quite open and flat. The outside of this bowl-shaped body is technically known as the exumbrella and the inside or underside is called the subumbrella.

This body usually, but not always, has tentacles attached to the bell margin - there can be many hundreds of tentacles, or as few as one (or zero). In most species, arrangement of tentacles around the bell is in some sort of four- or eight-part symmetry, or multiple of four or eight. In a few species, the tentacles are attached either on the outside of the bell above the margin, or on the inside, above the margin, but attachment at the margin is most common. In the center of the underside of the bell (the subumbrella) is some sort of feeding structure that includes a central mouth opening and often some other highly ornamented structures, called oral arms, that are used to help grasp (and sometimes digest) prey. The oral arms may be many cm long, spiraled and frilly, or they may be short and highly divided, sometimes with perforations, and sometimes with accessory clublike structures hanging down around the central mouth.

The tentacles, edges of the mouth (usually called lips), and the oral arms are covered with thousands of microscopic stinging structures called cnidocysts or nematocysts (produced by cells called cnidocytes), that are used to catch prey or for defense. (These structures, also known as cnidae are common to all animals in the phylum Cnidaria.) Cnidocysts are tiny capsules filled with a combination of toxins and enzymes that either are triggered, largely by mechanical pressure, to evert a long, spined tube that either penetrates or entangles the prey, making it easier to capture and move to the mouth. In some species of jellyfish, the outer surface of the bell is also sprinkled with cnidocysts, which may have either protective or prey-capturing roles.

The digestive system of most jellyfish includes a short stomach or gut (called the manubrium) above the mouth, which then opens into a system of thin canals that carry nutrients around the bell. These radial canals are located on the underside of the bell. They sometimes terminate in a ring canal that runs around the bell margin, but that isn't present in some species. In many species, the tentacles are hollow and open to the canal system for further circulation of nutrients. Waste materials are voided back out through the mouth, usually in a loosely compacted bolus.

Different species of jellyfish have different innate buoyancies, so when they are not swimming, some hang neutrally in the water, while others slowly sink when passive; a few float. Although a few of the largest jellyfish are strong swimmers, jellyfish are subject to the oceans currents, tides and waves for their large-scale movements. Animals in the sea whose movements are determined by these oceans currents are called plankton. In contrast, fish, marine mammals, squid, and a few other strong swimmers who can move beyond where natural ocean forces carry them are called nekton.

Jellyfish are carnivores, feeding on a wide variety of small ocean organisms, including zooplankton, small fish, and often, other jellyfish. Most jellyfish are passive drifters and/or slow swimmers. They move so as to create a local current forcing nearby prey within reach of their tentacles or oral arms, which then ensnare and paralyze the prey with their venomous cnidocysts, and bring the prey to the mouth. Some species digest prey within folds of the long trailing oral arms.

Jellyfish lack basic sensory organs and a brain, but their nervous systems and rhopalia allow them to perceive stimuli, such as light and odour, and respond quickly. The body of an adult is made up of 94–98% water. The bell consists of a layer of epidermis, gastrodermis, and a thick, intervening layer called mesoglea that produces most of the jelly. Some jellyfish, including the edible group known as the Rhizostomeae, have very thick, stiff, almost cartilaginous jelly, whereas other species are very soft and floppy. Most species are approximately the consistency of cold Jell-O (clear dessert gelatin).

Jellyfish are an important source of food to the Chinese community and in many Asian countries. Only scyphozoan jellyfish belonging to the order Rhizostomeae are harvested for food; about 12 of the approximately 85 known species of Rhizostomeae are being harvested and sold on international markets.

Commercial Jellyfish Fisheries in South East Asia - Commercial Jellyfish Fisheries in South East Asia. A few large jellyfish species in the order Rhizostomeae constitute an important food in Chinese cooking. For more than 1700 years, they have been exploited along the coasts of China. Such jellyfish became an important fishery commodity of Southeast Asian countries in the 1970's with increasing demand from the Japanese market. Recently, Japan has imported 5400-10,000 tons of jellyfish products per year, valued at about 25.5 million US dollars, annually from the Philippines, Vietnam, Thailand, Malaysia, Indonesia, Singapore and Myanmar. Judging from the type names at market and the external appearance of the semi-dried products, the edible jellyfish harvest in Southeast Asia is composed of more than 8 species. They are caught by various kinds of fishing gear including set nets, drift nets, hand nets, scoop nets, beach seines and hooks. The fishery is characterized by large fluctuations of the annual catch and a short fishing season that is restricted from two to four months. The average annual catch of jellyfish between 1988 and 1999 in Southeast Asia is estimated to be about 169,000 metric tons in wet weight and the worldwide catch is approximately 321,000 metric tons. Needs for future study on the biology of rhizostome jellyfish are discussed as they relate to understanding population fluctuations.

Photographs

Jelly Fish Links
Wikipedia Encyclopedia

South Carolina Dept. Natural Resources Jelly Fish Information - Diagrams and text show the anatomy of the jellyfish and its lifecycle, as well as several common species. From the South Carolina Department of Natural

Research on JELLYFISH - From FRDC

Jelly Fish Recipes
Jelly Fish Recipes from Food Downunder

US Food & Drug Administration:
US FDA - EU SEAFOOD PROCESSOR EXPORT CERTIFICATE LISTS
In the past the EU has accepted and used the FDA list of approved seafood establishments for acceptance of U.S. seafood shipments. However, due to a change in EU legislation, the EU began maintaining their own Official List of approved establishments. This has resulted in two separate (and different) lists:

• FDA list of approved establishments
• Official EU list (available in PDF*) updated 04/29/2008

See Also

Exporters of Jelly Fish  |  Importers of Jelly Fish  |  Processors of Jelly Fish  |  Wholesale Suppliers of Jelly Fish  |  Seafood Agents for Jelly Fish