Jellyfish are animals of the phylum Cnidaria, class Scyphozoa, order Semaeostomeae and family Cyaneidae. The phylum Cnidaria is an incredibly ancient group of invertebrate animals, stretching back hundreds of millions of years. Jellyfish are among the oldest types of multicellular animals. True jellyfish have a number of distinguishing characteristics by which they are classified.Know More
Jellyfish are universally planktonic in their adult stage, meaning that they have only minimal ability to propel themselves through water, and are carried along freely by ocean currents. Jellyfish have minimal sensory capabilities and no nervous systems, with each part responding only to its immediate environment without any coordination with the rest of the organism. The body of a jellyfish is composed of a gel-like substance known as mesoglia, which is about 90 percent water, surrounded by a skin only a single cell in thickness.
Jellyfish have distinctive weapons, known as nematocysts, for hunting prey. These are venom-bearing barbs found in great numbers in their tentacles. These weapons are shared only by jellyfish and related groups, such as sea anemones. Jellyfish use one of the major cnidarian body plans, a free-floating bell with trailing tentacles, known as a medusa, while anemones use the other body plan, a sessile stalk with upward-pointed tentacles, known as a polyp.Learn more about Jellyfish
Jellyfish are invertebrates composed of gelatinous substances and water. The creatures are similar to sea anemones and coral, which all belong to the phylum Cnidaria, as stated by the National Oceanic and Atmospheric Association.Full Answer >
Jellyfish primarily eat plankton, which are organisms that lack the strength and size to swim and therefore drift in marine and freshwater currents. Larger species of jellyfish also eat crustaceans, fish and other jellyfish. Jellyfish are carnivorous and primarily feed on animals. Some jellyfish have tissue containing symbiotic algae, which enables them to receive energy through photosynthesis.Full Answer >
Although they may not look like it, many animals belonging to the phylum Cnidaria actually have a quite significant economic importance for humans, especially those belonging to the Anthozoa class. For instance, scientists have discovered many chemical compounds in Cnidarians that can be used to treat cancer and other illnesses.Full Answer >
Jellyfish do not have brains, and most barely have nervous systems. They have primitive nerve cells that help them orient themselves in the water and sense light and touch. Jellyfish can be tiny or grow to several feet in diameter.Full Answer >