| Calvadosia cruxmelitensis | |
|---|---|
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Cnidaria |
| Class: | Staurozoa |
| Order: | Stauromedusae |
| Family: | Kishinouyeidae |
| Genus: | Calvadosia |
| Species: | C. cruxmelitensis |
| Binomial name | |
| Calvadosia cruxmelitensis (Corbin, 1978) | |
| Synonyms | |
| |
Calvadosia cruxmelitensis is a stalked jellyfish which inhabits the intertidal and sublittoral zones of rocky coasts in south-western England and the Atlantic coast of Ireland.
The Latin name of this species, cruxmelitensis, refers to the arrangement of the white nematocyst capsules (stinging organs) in the distinctive pattern of a Maltese Cross. [1] In 2010, Natural England, the Guardian and the Oxford University Museum of Natural History ran a competition asking members of the public to provide a common name for this species. The name St John's jellyfish was eventually chosen. Runner up names included Marmalade shred jellyfish and Maltese cross medusa. [2]
C. cruxmelitensis is the smallest member of the stalked jellyfishes growing to a maximum of 1.2 cm in diameter and 0.8 cm in height. It characteristically appears 'stalkless', although in fact it attaches to its location via a short stalk that terminates in a broad basal disc. It appears to have the unusual capacity to hold itself very rigidly in this posture, even when subjected to agitation caused by tidal flow.
Calvadosia cruxmelitensis has a translucent, maroon, broad funnel-shaped bell which is divided by hollow septa. The septa walls contain the gonads, which are thick, linear and Y-shaped, joining at the base of the bell and then extending outwards to the arms. It has eight arms which are arranged in a circle. On the end of each arm is a cluster of up to thirty five tentacles, each of which has a rounded head. Unlike Haliclystus salpinx , C. cruxmelitensis does not have tentacle anchors. [1] [3]
Originally identified inhabiting Wembury Bay, Devon, [1] C. cruxmelitensis is now known to live on the Atlantic coasts of Ireland and the south-west coast of England, specifically from Swanage to North Devon. The English population has undergone a severe reduction in size in recent years, its numbers dropping by 90% from the 1970s to 2005. [4]
It is found on rocky shores which are exposed to moderately strong currents and waves. It lives in shallow water (sublittorally) or close the low tide mark (intertidally). Unlike most stalked jellyfish it does not attach itself to marine eelgrass, preferring to inhabit Irish moss and false Irish moss. [3]
Members of this species are gonochoristic, that is they are either male or female in gender. Individuals are believed to reach sexual maturity at about half of their maximum size. [1] Gametes are produced from the gonads, which are located on the sepal walls, and shed into the surrounding water where fertilisation takes place. The resultant zygote develops into a free swimming planula larva before attaching itself to a suitable site. Once attached the larva encysts before developing into a small polyp followed by the adult form. [3] Like all stalked jellyfish, a single C. cruximelitensis individual is believed to live for only one year. [5] Numbers of this species in a given location are greatest in mid-winter and lowest in mid-summer. [1] [5]
A draft genome has been published [6] and its phylogenetic position relative to other Cnidaria has been determined using genome-scale data. [7] Its genome is relatively compact (~210 megabases) compared to other cnidarians and other animals. [6]
Cnidaria is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in freshwater and marine environments, including jellyfish, hydroids, sea anemone, corals and some of the smallest marine parasites. Their distinguishing features are a decentralized nervous system distributed throughout a gelatinous body and the presence of cnidocytes or cnidoblasts, specialized cells with ejectable flagella used mainly for envenomation and capturing prey. Their bodies consist of mesoglea, a non-living jelly-like substance, sandwiched between two layers of epithelium that are mostly one cell thick.
Jellyfish, also known sea jellies, are the medusa-phase of certain gelatinous members of the subphylum Medusozoa, which is a major part of the phylum Cnidaria.
The Scyphozoa are an exclusively marine class of the phylum Cnidaria, referred to as the true jellyfish.
Box jellyfish are cnidarian invertebrates distinguished by their box-like body. Some species of box jellyfish produce potent venom delivered by contact with their tentacles. Stings from some species, including Chironex fleckeri, Carukia barnesi, Malo kingi, and a few others, are extremely painful and often fatal to humans.
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 mainly like muscular hydrostats. Most forms of tentacles are used for grasping and feeding. Many are sensory organs, variously receptive to touch, vision, or to the smell or taste of particular foods or threats. Examples of such tentacles are the eyestalks of various kinds of snails. Some kinds of tentacles have both sensory and manipulatory functions.
Medusozoa is a clade in the phylum Cnidaria, and is often considered a subphylum. It includes the classes Hydrozoa, Scyphozoa, Staurozoa and Cubozoa, and possibly the parasitic Polypodiozoa. Medusozoans are distinguished by having a medusa stage in their often complex life cycle, a medusa typically being an umbrella-shaped body with stinging tentacles around the edge. With the exception of some Hydrozoa, all are called jellyfish in their free-swimming medusa phase.
Stauromedusae are the stalked jellyfishes. They are the sole living members of the class Staurozoa and belong to the medusozoa subphylum of Cnidaria. They are unique among medusa jellyfish in that they do not have an alternation of polyp and medusa life cycle phases, but are instead interpreted as an attached medusa stage, with a lifestyle more resembling that of polypoid forms. They have a generally trumpet-shaped body, oriented upside-down in comparison with other jellyfish, with the tentacles projecting upwards, and the stalk located in the centre of the umbrella.
Staurozoa is a class of Medusozoa, jellyfishes and hydrozoans. It has one extant order: Stauromedusae with a total of 50 known species. A fossil group called Conulariida has been proposed as a second order, although this is highly speculative. The extinct order is largely unknown and described as a possibly cnidarian clade of marine life with shell-like structures, the Conulariida. Staurozoans are small animals that live in marine environments, usually attached to seaweeds, rocks, or gravel. They have a large antitropical distribution, a majority found in boreal or polar, near-shore, and shallow waters. Few staurozoans are found in warmer tropical and subtropical water environments of the Atlantic, Indian, and Pacific Ocean basins, but most are known from the Northern Hemisphere. Over the years the number of discovered species has increased, with an estimated 50 species currently recognized. Information on Staurozoa is sparse, and it is one of the least studied groups within Cnidaria. While often neglected, correctly recognizing the characteristics of this class is crucial for understanding cnidarian evolution.
Pelagia noctiluca is a jellyfish in the family Pelagiidae and the only currently recognized species in the genus Pelagia. It is typically known in English as the mauve stinger, but other common names are purple-striped jelly, purple stinger, purple people eater, purple jellyfish, luminous jellyfish and night-light jellyfish. In Greek, pelagia means "(she) of the sea", from pelagos "sea, open sea"; in Latin noctiluca is the combining form of nox, "night"", and lux, "light"; thus, Pelagia noctiluca can be described as a marine organism with the ability to glow in the dark (bioluminescence). It is found worldwide in tropical and warm temperate seas, although it is suspected that records outside the North Atlantic region, which includes the Mediterranean and Gulf of Mexico, represent closely related but currently unrecognized species.
Turritopsis dohrnii, also known as the immortal jellyfish, is a species of small, biologically immortal jellyfish found worldwide in temperate to tropic waters. It is one of the few known cases of animals capable of reverting completely to a sexually immature, colonial stage after having reached sexual maturity as a solitary individual. Others include the jellyfish Laodicea undulata and species of the genus Aurelia.
Chrysaora hysoscella, the compass jellyfish, is a common species of jellyfish that inhabits coastal waters in temperate regions of the northeastern Atlantic Ocean, including the North Sea and Mediterranean Sea. In the past it was also recorded in the southeastern Atlantic, including South Africa, but this was caused by confusion with close relatives; C. africana, C. fulgida and an undescribed species tentatively referred to as "C. agulhensis".
Hydroidolina is a subclass of Hydrozoa and makes up 90% of the class. Controversy surrounds who the sister groups of Hydroidolina are, but research has shown that three orders remain consistent as direct relatives: Siphonophorae, Anthoathecata, and Leptothecata.
Sea anemones are a group of predatory marine invertebrates constituting the order Actiniaria. Because of their colourful appearance, they are named after the Anemone, a terrestrial flowering plant. Sea anemones are classified in the phylum Cnidaria, class Anthozoa, subclass Hexacorallia. As cnidarians, sea anemones are related to corals, jellyfish, tube-dwelling anemones, and Hydra. Unlike jellyfish, sea anemones do not have a medusa stage in their life cycle.
Haliclystus auricula is a stalked jellyfish or Kaleidoscope jellyfish named for its shape resembling a funnel-shaped kaleidoscope that has eight arms typically found in the Northern Hemisphere. The Staurozoan is classified within the phylum Cnidaria under the kingdom Animalia. Under its genus, H. auricula is considered the type species.
Lucernaria janetae is an exceptionally large stalked jellyfish discovered on deep-sea hydrothermal vents on the East Pacific Rise in 2003 and described in 2005.
Haliclystus antarcticus is a stalked jellyfish which lives on rocky shore lines in the Southern hemisphere.
Anthopleura ballii, commonly known as the red speckled anemone, is a species of sea anemone in the family Actiniidae. It is found in shallow water in the northeastern Atlantic Ocean.
Turritopsis rubra, commonly referred to as the Crimson Jelly, is a hydrozoan within the family Oceaniidae. The species is native to New Zealand and southern Australia, typically appearing near shorelines in the summer months. The species follows a distribution pattern across the southern Pacific Ocean and can frequently be found in shallow coastal waters.
Polypodium is a genus of cnidarians that parasitizes in the eggs of sturgeon and similar fishes. It is one of the few metazoans (animals) that live inside the cells of other animals.
Clytia hemisphaerica is a small hydrozoan-group cnidarian, about 1 cm in diameter, that is found in the Mediterranean Sea and the North-East Atlantic Ocean. Clytia has the free-swimming jellyfish form typical of the Hydrozoa, as well as vegetatively propagating polyps.