Black Sea Nettle Fact Sheet

Common Name:

Black Sea Nettle, Black Jellyfish

Scientific Name:

Chrysaora achlyos

Wild Status:



Large bodies of water


Pacific coast of the USA


Deep ocean

Life Span:



4ft long bell; 25ft+ tentacles

Cool Facts:

  • Like all jellies, the Black Sea Nettles have no brains, respiratory or digestive systems, hearts, or eyes.
  • Without warning, they have shown up on beaches in mass numbers. Some experts believe it is due to climate events such as El Niño, while others theorize fertilizer rich runoff from farms leads to large numbers of plankton that attract these jellies.
  • Their diet most likely consists of small fish, plankton, and other jelly fish
  • Their sting is said to not be nearly as painful as other jellyfish stings
  • These two previous facts could be related as jellyfish that feed on larger animals require stronger toxins. Jellyfish that feed on smaller animals are typically less lethal.


Black Sea Nettles are some of the most intriguing and mysterious animals to grace the Pacific Coast. They are considered the largest invertebrates discovered in the past century. Humans rarely make contact with these jellies, and when they do, it is typically when mass swarms of jellies swim up to the surface. Events such as these are rare and therefore very important to scientists, especially since the black jellyfish is difficult to maintain in captivity. There have been some sightings in the past ten years, but much about their life cycle, behavior, and biology remains a mystery. When not near the surface of the water, it is thought they live at great depths, where the sun does not reach and the waters are still.   Much remains to be learned about these jellyfish and their next mass appearance on the beaches of California, Mexico, and even Canada may offer further insights into their nature.

Taxonomic Breakdown:

Kingdom: Animalia Phylum: Cnidaria Class: Scyphozoa Order: Semaeostomeae Family: Pelagiidae Genus: Chrysaora Species: C. achlyos

Conservation & Helping:

Not enough is currently known about the Black Sea Nettle to accurately describe its conservation status. However, all marine animals are harmed by pollution, including things like plastic bags.

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