''Copula'' is a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

box jellyfish Box jellyfish (class Cubozoa) are cnidaria Cnidaria () is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in Fresh water, freshwater and Marine habitats, marine environments, predominantly the latt ...

in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Tripedaliidae Tripedaliidae is a family of box jellyfish within class Cubozoa. Species * ''Copula'' Bentlage, Cartwright, Yanagihara, Lewis, Richards & Collins, 2010 ** '' Copula sivickisi'' (Stiasny, 1926) * '' Tripedalia'' Conant, 1897 ** '' Tripedalia binat ...

of the phylum

Cnidaria Cnidaria () is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in Fresh water, freshwater and Marine habitats, marine environments, predominantly the latter. Their distinguishing feature is cnidocyt ...

. The only

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

in the genus is ''Copula sivickisi'', a very small gelatinous, bell-shaped jellyfish with four tentacles that is active only at night. It is unusual among box jellyfish in having a mating ritual and internal fertilization. Its scientific name honours the Lithuanian zoologist

Pranciškus Baltrus Šivickis Pranciškus Baltrus Šivickis (born September 30, 1882, in the Raseiniai region of central Lithuania—died October 12, 1968) was a Lithuanian zoologist who moved to the United States where he completed his education. He became a professor at the ...

Description

''Copula sivickisi'' is a very small species of jellyfish, the

medusa In Greek mythology, Medusa (; Ancient Greek: Μέδουσα "guardian, protectress"), also called Gorgo, was one of the three monstrous Gorgons, generally described as winged human females with living venomous snakes in place of hair. Those ...

growing to about in diameter. The bell is a more "boxy" shape than that of the umbrella-like true jellyfishes. The eight gonads can be seen inside the transparent bell. In males these are orange hemispherical structures near the apex of the bell, and in females they are white-speckled, leaf-like structures. There is a central

manubrium The sternum or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major blood vessels from injury. Sh ...

, a transparent tubular structure hanging down from the centre of the underside of the bell and there are four slender

tentacle In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work main ...

s hanging from the rim, each banded with orange. In mature females, the edge of the bell is patterned with orange-brown markings.

Distribution

''Copula sivickisi'' is found in shallow warm waters in the Pacific Ocean and one Indian Ocean location (the west coast of Sumatra). Its range extends from Japan and Taiwan to the Philippines, Vietnam and Thailand, northern Australia, New Zealand, Micronesia and Hawaii.

Behaviour

''Copula sivickisi'' is nocturnal and hides during the day. There are adhesive pads on the top of the bell and it can secure itself with these to objects. On sinking to the seabed soon after dawn it spends a few minutes selecting a good location and preferentially chooses the underside of a coral, stone or blade of

seagrass Seagrasses are the only flowering plants which grow in marine environments. There are about 60 species of fully marine seagrasses which belong to four families ( Posidoniaceae, Zosteraceae, Hydrocharitaceae and Cymodoceaceae), all in the ...

. It then folds its tentacles inside the bell and flattens itself, making it very difficult for humans to observe it in its natural environment. It reactivates soon after dusk and rises in the water column before starting feeding. Most jellyfish liberate sperm and eggs into the sea and fertilisation is a chancy business, but this jellyfish has been observed to have a more elaborate mating ritual. A male will grab a female by one tentacle and start to pull her around. The pair entwine and place their manubria close together. The male then passes a red

spermatophore A spermatophore or sperm ampulla is a capsule or mass containing spermatozoa created by males of various animal species, especially salamanders and arthropods, and transferred in entirety to the female's ovipore during reproduction. Spermatophores ...

(bundle of sperm) to one of the female's tentacles which thrusts it into her manubrium. Females have been observed mating in this way with several different males, up to eight times in a two-hour period. Eggs inside the female's bell are fertilised by the sperm, and a mucous strand of embryos is produced and released into the sea some two or three days later. Here they develop into polyps, another stage in the complex life cycle of

. ''Copula sivickisi'' has twenty-four eyes grouped on four stalked

rhopalia Rhopalia (singular: rhopalium) are small sensory structures of certain Scyphozoan (true jellyfish) and Cubozoan (box jellyfish) species. Description The structures typically occur in multiples of four, are bell shaped and face outward from invag ...

situated on the rim of the bell. It is attracted to light and feeds on

zooplankton Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...

including phosphorescent organisms. Its typical feeding mechanism is to rise to the surface and then sink through the water with its tentacles extended to catch prey. Typical prey items are

copepod Copepods (; meaning "oar-feet") are a group of small crustaceans found in nearly every freshwater and saltwater habitat. Some species are planktonic (inhabiting sea waters), some are benthic (living on the ocean floor), a number of species have p ...

s, hooded shrimps, zoea larvae and the

bioluminescent Bioluminescence is the production and emission of light by living organisms. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some fungi, microorganisms including some b ...

dinoflagellate ''

Noctiluca ''Noctiluca scintillans'' is a marine species of dinoflagellate that can exist in a green or red form, depending on the pigmentation in its vacuoles. It can be found worldwide, but its geographical distribution varies depending on whether it is ...

'', all of which are present near the water surface at night.

References

{{Taxonbar, from1=Q2469196, from2=Q16980959 Tripedaliidae Invertebrates of New Zealand Animals described in 1926