©Ian R.T. MacGregor, Vancouver Aquarium

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Jellies (Phylum Cnidarian) have been on the planet for over 650 million years! There are over 200 species of jellies which represent a variety of sizes and colors such as red, purple, yellow, green, and blue. Jellies are composed of 95% water and have stinging cells, called nematocysts in their tentacles that they use to stun prey and defend themselves. Toxins from the stinging cells of most jellies will cause only minor pain, however some species re so toxic they can cause severe symptom including nausea, cramps, high blood pressure, pain, and even death.

Jelly populations are actually thriving! Scientists believe that overfishing and climate disruption has created an increase in jellies because there are fewer marine predators such as sea turtles, sharks, tuna, and swordfish to eat them. During the 1990’s, jelly populations were so large that they clogged fishing nets, pipes and power plants in the Bering Sea. Although most jelly populations are stable, certain species such as the box and upside-down jellies, have specific habitat requirements and the degradation of the mangrove forests on which they rely is reducing their population densities.

The AZA Aquatic Invertebrate Taxon Advisory Group is involved in the conservation and management of a large variety of taxa including anemones, seas cucumbers, coral, octopus and jellies. AZA-accredited aquariums often highlight the variations in size, color and shape exhibited by jellies. Scientists at AZA-accredited facilities are currently researching the biochemical make-up of some of the deadly box jellyfish species’ toxins to develop anti-venom serums for victims of this deadly sting.

Sea Jelly Facts

Status Not Threatened
Size Jellies can range in size from microscopic to 8 feet in diameter, with tentacles the size of football fields.
Appearance Most people are most familiar with the classic bell-shapes jelly, however they come in all shapes and have tentacles of varying lengths.
Habitat Jellies live mostly in shallow coastal waters throughout the world, but some inhabit depths of 12,000 feet! There is one freshwater species that lives in the Amazon River.
Diet Jellies eat small fish, eggs, and zooplankton.  Some of the larger species can eat crustaceans and other jellies.
Breeding Jellies reproduce externally.