| Lucernaria janetae | |
|---|---|
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Cnidaria |
| Class: | Staurozoa |
| Order: | Stauromedusae |
| Family: | Lucernariidae |
| Genus: | Lucernaria |
| Species: | L. janetae |
| Binomial name | |
| Lucernaria janetae Collins and Daly, 2005 [1] | |
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. [1]
This species was named after Dr Janet Voight of the Field Museum of Natural History in Chicago "in recognition of her commitment to discovering and describing deep-sea invertebrates". [1]
L. janetae is an exceptionally large stalked jellyfish. It has eight distinct arms which are tipped with clusters of about 100 secondary tentacles. Small juvenile forms of this species sometimes have small, ovate primary tentacles but these are always absent in the adult organism. This species does not have anchor tentacles. The 'umbrella' (calyx) of this organism is goblet-shaped and creamy white with a hint of green or orange. It is up to 100mm wide and 50mm deep, a significantly larger calyx size than those of other members of this genus. The 'stalk' (peduncle) is the same colour as the calyx. Unlike the peduncles of many Stauromedusae, which often have 4 chambers, the peduncle of L. janetae only has a single chamber. [1]
It is the only known species of Lucernaria from the Pacific Ocean. [1] All other members of this genus inhabit the Atlantic Ocean. [1] It is the first and currently the only known Stauromedusan described as living near a hydrothermal vent. [1] L. janetae has been found at depths ranging between 2500-2700m. [1] [2] When originally described it was believed to be the second deepest-living member of the genus Lucernaria, [1] the deepest living known Stauromedusan was then Lucernaria bathyphila , recorded at a depth of 2800m. [3] However a recent study found organisms which could be L. janetae at 3001m. [4] As of 2006 [update] , these organisms are, the deepest living known Stauromedusae. Unlike most Stauromedusae, which are solitary organisms, L. janetae forms large populations and, where it occurs, is the dominant macrofauna. [1]
L. janetae eats small pelagic crustaceans [1] which probably include amphipods, a common prey of Stauromedusae, since amphipods ( Halice hesmonectes ) were found in the same region as a possible population of L. janetae. [2]
L. janetae has 8 gonads which are shaped like lances and arranged in pairs extending from the centre of the calyx to the base of the arms. [1] They give the organism an orange/pink colour when reproductively active. The scientists who originally identified L. janetae have speculated that this species may also be capable of asexual reproduction. [1] This had not been shown for any Stauromedusan at the time the paper was written, although it has subsequently been suggested for Haliclystus antarcticus . [5] Stauromedusae are believed to be sessile, except in the larval stage. The larvae are able to move by crawling but are believed not to migrate large distances. It is therefore presently unclear as to how L. janetae is able colonise multiple unconnected vents. [2] [4]
Siboglinidae is a family of polychaete annelid worms whose members made up the former phyla Pogonophora and Vestimentifera. The family is composed of around 100 species of vermiform creatures which live in thin tubes buried in sediment (Pogonophora) or in tubes attached to hard substratum (Vestimentifera) at ocean depths ranging from 100 to 10,000 m. They can also be found in association with hydrothermal vents, methane seeps, sunken plant material, and whale carcasses.
Aurelia aurita is a species of the family Ulmaridae. All species in the genus are very similar, and it is difficult to identify Aurelia medusae without genetic sampling; most of what follows applies equally to all species of the genus.
Riftia pachyptila, commonly known as the giant tube worm and less commonly known as the giant beardworm, is a marine invertebrate in the phylum Annelida related to tube worms commonly found in the intertidal and pelagic zones. R. pachyptila lives on the floor of the Pacific Ocean near hydrothermal vents. The vents provide a natural ambient temperature in their environment ranging from 2 to 30 °C, and this organism can tolerate extremely high hydrogen sulfide levels. These worms can reach a length of 3 m, and their tubular bodies have a diameter of 4 cm (1.6 in).
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. Stauromedusae usually has eight marginal arms at the top of the calyx. They reach their adult sizes within several weeks, typically 1 to 4 centimeters in length.
Staurozoa is a class of Medusozoa. 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.
Kiwa hirsuta is a crustacean discovered in 2005 in the South Pacific Ocean. This decapod, which is approximately 15 cm (5.9 in) long, is notable for the quantity of silky blond setae covering its pereiopods. Its discoverers dubbed it the "yeti lobster" or "yeti crab".
The Bythograeidae are a small family of blind crabs which live around hydrothermal vents. The family contains 16 species in six genera. Their relationships to other crabs are unclear. They are believed to eat bacteria and other vent organisms. Bythograeidae are a monophyletic, sister taxon of the superfamily Xanthoidea which split to inhabit hydrothermal vents around the Eocene.
Chrysomallon squamiferum, commonly known as the scaly-foot gastropod, scaly-foot snail, sea pangolin, or volcano snail is a species of deep-sea hydrothermal-vent snail, a marine gastropod mollusc in the family Peltospiridae. This vent-endemic gastropod is known only from deep-sea hydrothermal vents in the Indian Ocean, where it has been found at depths of about 2,400–2,900 m (1.5–1.8 mi). C. squamiferum differs greatly from other deep-sea gastropods, even the closely related neomphalines. In 2019, it was declared endangered on the IUCN Red List, the first species to be listed as such due to risks from deep-sea mining of its vent habitat.
In zoology, deep-sea gigantism or abyssal gigantism is the tendency for species of deep-sea dwelling animals to be larger than their shallower-water relatives across a large taxonomic range. Proposed explanations for this type of gigantism include necessary adaptation to colder temperature, food scarcity, reduced predation pressure and increased dissolved oxygen concentrations in the deep sea. The harsh conditions and inhospitality of the underwater environment in general, as well as the inaccessibility of the abyssal zone for most human-made underwater vehicles, have hindered the study of this topic.
Alviniconcha is a genus of deep water sea snails, marine gastropod mollusks in the family Paskentanidae. These snails are part of the fauna of the hydrothermal vents in the Indian and Western Pacific Ocean. These and another genus and species within the same family are the only known currently existing animals whose nutrition is derived from an endosymbiotic relationship with a member of bacteria from phylum Campylobacterota and Gammaproteobacteria, occurring as endosymbionts within the vacuoles of Alviniconcha ctenidia. All species of Alviniconcha are thought to be foundational species found near hydrothermal venting fluid supplying their bacterial endosymbionts with vent derived compounds such as hydrogen sulfide. These snails can withstand large variations in temperature, pH, and chemical compositions.
Haliclystus is a genus of stalked jellyfish that contains 11 species and one nomen nudum. It is the largest genus in the order Stauromedusae. Members of this genus are found in the Pacific, Atlantic, Indian, Arctic, and Southern oceans. Two members of this genus, Haliclystus kerguelensis and Haliclystus antarcticus, are found in the Southern hemisphere only. The remaining 9 members are found in the Northern hemisphere only.
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.
Haliclystus antarcticus is a stalked jellyfish which lives on rocky shore lines in the Southern hemisphere.
Bathymodiolus thermophilus is a species of large, deep water mussel, a marine bivalve mollusc in the family Mytilidae, the true mussels. The species was discovered at abyssal depths when submersible vehicles such as DSV Alvin began exploring the deep ocean. It occurs on the sea bed, often in great numbers, close to hydrothermal vents where hot, sulphur-rich water wells up through the floor of the Pacific Ocean.
Haliclystidae is a family of stalked jellyfish in the order Stauromedusae.
Thermarces cerberus is a species of ray-finned fish in the family Zoarcidae. This fish, commonly known as the pink vent fish, is associated with hydrothermal vents and cold seeps at bathypelagic depths in the East Pacific.
Haliclystus octoradiatus, common name spotted kaleidoscope jellyfish, is a stalked jellyfish in the family Lucernariidae.
Manania handi is a species of stalked jellyfish found in the Pacific Ocean along the west coast of North America. This species can be found in shallow waters at low tide on soft substrates such as seagrass (Phyllospadix), but the related M. gwilliami have also been recovered at depths of >10 metres. This may reflect that intertidal specimens represent the fringes of a population that is typically more commonly found in the subtidal zone.
Manania gwilliami is a species of stalked jellyfish found in intertidal and subtidal zones on the west coast of North America. The stalk (peduncle) is described as being as long or longer than the calyx; the calyx typically has mottled pigmentation throughout. The name "gwilliami" refers to G.F. Gwilliam who described a number of stauromedusae in the mid-20th century.