Cyanea is a cosmopolitan genus of stinging jellyfish

Jellyfish

Jellyfish are free-swimming members of the phylum Cnidaria. Medusa is another word for jellyfish, and refers to any free-swimming jellyfish stages in the phylum Cnidaria...

, primarily found in northern waters of the Atlantic

Atlantic Ocean

The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

 and Pacific Ocean

Pacific Ocean

The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

s. The same genus name has been given to a genus of plants of the Hawaiian lobelioids

Hawaiian lobelioids

The Hawaiian lobelioids are a group of flowering plants in the bellflower family, Campanulaceae, all of which are endemic to the Hawaiian Islands. This is the largest plant radiation in the Hawaiian Islands, and indeed the largest on any island archipelago, with over 125 species...

, an example of a parahomonym (same name, different kingdom

Kingdom (biology)

In biology, kingdom is a taxonomic rank, which is either the highest rank or in the more recent three-domain system, the rank below domain. Kingdoms are divided into smaller groups called phyla or divisions in botany...

).

Species

The taxonomy

Biological classification

Biological classification, or scientific classification in biology, is a method to group and categorize organisms by biological type, such as genus or species. Biological classification is part of scientific taxonomy....

 of Cyanea species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 is not fully agreed upon. Some zoologists

Zoology

Zoology |zoölogy]]), is the branch of biology that relates to the animal kingdom, including the structure, embryology, evolution, classification, habits, and distribution of all animals, both living and extinct...

 have suggested that all species within the genus should be treated as one. However, in the North Sea

North Sea

In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...

 at least, the lion's mane jellyfish

Lion's mane jellyfish

The lion's mane jellyfish is the largest known species of jellyfish. Its range is confined to cold, boreal waters of the Arctic, northern Atlantic, and northern Pacific Oceans, seldom found farther south than 42°N latitude. Similar jellyfish, which may be the same species, are known to inhabit...

 and the blue jellyfish

Blue jellyfish

Cyanea lamarckii, also known as the Blue jellyfish or Bluefire jellyfish, is a species of jellyfish in the family Cyaneidae. Populations in the western Pacific around Japan are sometimes distinguished as Cyanea nozakii or Cyanea capillata nozakii.-Distribution:This species is found in the pelagic...

 appear as distinct species. Cyanea may be a species complex

Species complex

A species complex is a group of closely related species, where the exact demarcation between species is often unclear or cryptic owing to their recent and usually still incomplete reproductive isolation. Ring species, superspecies and cryptic species complex are example of species complex...

 of recently diverged species.

• Cyanea annasethe Haeckel 1880
• Cyanea annaskala von Lendenfeld,1884
• Cyanea buitendijki Stiasny, 1919
• Cyanea capillata (Linnaeus, 1758)
• Cyanea citrae (Kishinouye, 1910)
• Cyanea ferruginea Eschscholtz, 1929
• Cyanea fulva Agassiz, 1862
• Cyanea lamarckii Péron & Lesueur, 1809
• Cyanea mjobergi Stiasny 1921
• Cyanea muellerianthe Haacke, 1887
• Cyanea nozakii Kishinouye, 1891
• Cyanea postelsi Brandt, 1838
• Cyanea purpurea Kishinouye, 1910
• Cyanea rosea Quoy & Gaimard 1824