The cubozoans are similar to the Scyphozoa ("true jellyfish") but the bell is square in cross section, with a velum-like structure called the velarium. The velarium restricts the size of the opening through which water is expelled when the bell contracts, thus increasing thrust and making them stronger swimmers than the Scyphozoa. There are four clusters of tentacles, one at each corner of the bell. The rhopalia of the Cubozoa differ from those of the Scyphozoa in possessing very complex eyes with lenses, corneas and retinas. The lens is capable of producing very sharp images, as good as human eyes but the focal length is longer than the distance between the lens and the retina making box jellyfish strangely far-sighted. Development is also different in the cubozoans. Each scyphistoma forms a single medusa via complete metamorphosis. Cubozoa includes the highly toxic box jellyfish, Chironex fleckeri,  found in tropical regions and often in swarms which can drift into bays, disrupting human activities.

Box jellies (also known as jellyfish) belong to the invertebrate Phylum Cnidaria, a diverse group of stinging animals whose members all possess stinging cells for feeding and protection. Jelly/jellyfish relatives include the sea anemones, corals, and Portuguese man-of- war. The box jellies, or Cubomedusae, are named for the squarish shape of their bell-shaped body. As a group, box jellies are found in shallow tropical seas throughout the Pacific, Indian, and Atlantic Oceans. They generally occur in quiet, shallow waters of protected bays and estuaries, and over sandy-bottomed shorelines, though some species have been reported in the open ocean. Box jellies apparently descend to deeper water during daylight hours, but during summer months, adults are often reported at the surface. The tentacles, well-armed with potent stinging cells can inflict a painful sting on unwary beach goers. An Australian relative, the notorious "sea wasp" box jelly (Chironex fleckeri), is deadly. While the sting of Hawaii's box jellies is not usually lethal, it is reported to be more painful than that of the more common Portuguese man-of-war." (Waikïkï Aquarium Education Department University of Hawai‘i-Mänoa, 2009.)

Barcode of Life Data Systems (BOLD) Stats
                                        

Specimen Records:	4	Public Records:	3
Specimens with Sequences:	3	Public Species:	2
Specimens with Barcodes:	3	Public BINs:	2
Species:	2
Species With Barcodes:	2

Access Published & Released Data: Download FASTA File

Collection Sites: world map showing specimen collection locations for Cubozoa