Anthoathecata

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Anthoathecata
Haeckel Anthomedusae.jpg
Anatomical details of Pandeidae (Filifera).
Lower left, top right: Neoturris pileata . Lower right: Stomotoca pterophylla .
From Kunstformen der Natur
by Ernst Haeckel (1904)
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Cnidaria
Class: Hydrozoa
Subclass: Hydroidolina
Order: Anthoathecata
Haeckel, 1879
Suborders

and see text

Synonyms
  • Anthomedusa Haeckel, 1879
  • Anthomedusae Cornelius, 1992
  • Anthoathecatae Cornelius, 1992 (emendation)
  • Athecata Hincks, 1868
  • Athecatae Hincks, 1868 (emendation)
  • Gymnoblastea Allman, 1871
  • Hydromedusa
  • Hydromedusae
  • Laingiomedusae
  • Stylasterina Hickson and England, 1905
  • Stylasterinae Hickson and England, 1905 (emendation)

Anthoathecata, or the athecate hydroids, are an order of hydrozoans belonging to the phylum Cnidaria. A profusion of alternate scientific names exists for this long-known and heavily discussed group. It has also been called Gymnoblastea and (with or without an emended ending -ae), Anthomedusa, Athecata, Hydromedusa, and Stylasterina. There are about 1,200 species worldwide. [1]

Contents

These hydrozoans always have a polyp stage. Their hydranths grow either solitary or in colonies. There is no firm perisarc around the polyp body. The medusae, or jellyfish, are solitary animals, with tentacles arising from the bell margin, lacking statocysts but possessing radial canals. Their gonads are on the manubrium ("handle"). [2]

Except in Eudendriidae and Laingiidae, prey can be captured by discharging harpoon-like structures (desmonemes) from chambers (cnidae) in specialized cells (nematocysts) on the tentacles. In hydrozoans, these are nearly always adhesive and entrapping, rather than puncturing and venomous as in other jellies. [2]

Systematics

It is not clear whether Stylaster californicus belongs in the Filifera. Upper left: blue top snail (Calliostoma ligatum). Stylaster californicus 2.jpg
It is not clear whether Stylaster californicus belongs in the Filifera.
Upper left: blue top snail (Calliostoma ligatum).

The close relationship of the orders Anthoathecata and Leptomedusae has been long known, but formerly it was also believed that these two were close to the order Limnomedusae. However, their closest relatives are the highly advanced Siphonophorae, whereas the Limnomedusae are a rather primitive group, and not very closely related to these three Leptolinae, and might instead belong to the subclass Trachylinae.

Some uncertainty existed regarding the taxonomy of the order Anthoathecata. The most simple scheme, used until recently by most authors since it was proposed in 1913, divided the order into a smaller suborder (Filifera) and a second larger one (Capitata), but several unusual Anthoathecatae did not fit into this arrangement, and a considerable number did so awkwardly. The Porpitidae, for example, are a highly aberrant group, and were at one time even considered a separate order "Chondrophora". However, they are currently considered to be derived from Zancleida. In the early 21st century, the well-known Hydra and its relatives – and most of the supposed filiferan infraorders Tubulariida and Moerisiida – were determined to be a very ancient lineage, recognized as suborder Aplanulata. [3] Although not all Anthoathecatae have been firmly placed in the phylogeny, most are fairly certainly assigned at least to one of the major subdivisions. As a notable exception, a prehistoric family, the Heterastridiidae, is still highly disputed regarding its relationships to the extant taxa, as are a small number of very aberrant and/or little-known species such as the aptly named Saccohydra problematica .

The family Clathrozoellidae is placed with the Filifera here; in others it is placed in the Leptomedusae and sometimes even synonymized with their family Clathrozoidae. By contrast, the supposed filiferan genus Anthohydra is in fact the leptomedusan Eugymnanthea ; similarly, " Gammaria " is also a leptomedusan and properly spelled Grammaria .

The supposed athecate family Monobrachiidae is apparently a close relative of the Olindiasidae, and belongs in the Limnomedusae. Halammohydridae and Otohydridae, sometimes placed here, appear to be trachyline hydrozoans of the order Actinulidae.

[4]

Infraorders and families

Hydractinia epiconcha belongs to the Margelina in the suborder Filifera. Hydractinia epiconcha01.jpg
Hydractinia epiconcha belongs to the Margelina in the suborder Filifera.
The well-known freshwater polyp Hydra viridissima, formerly placed in the Capitata, belongs to the Aplanulata. Mikrofoto.de-Hydra 15.jpg
The well-known freshwater polyp Hydra viridissima , formerly placed in the Capitata, belongs to the Aplanulata.
Polyorchis karafutoensis, a true member of the Capitata, on a 1995 stamp from Azerbaijan. Stamp of Azerbaijan 319.jpg
Polyorchis karafutoensis , a true member of the Capitata, on a 1995 stamp from Azerbaijan.

Related Research Articles

<span class="mw-page-title-main">Hydrozoa</span> Class of cnidarians

Hydrozoa is a taxonomic class of individually very small, predatory animals, some solitary and some colonial, most of which inhabit saline water. The colonies of the colonial species can be large, and in some cases the specialized individual animals cannot survive outside the colony. A few genera within this class live in freshwater habitats. Hydrozoans are related to jellyfish and corals and belong to the phylum Cnidaria.

<span class="mw-page-title-main">Chondrophore</span> Small group of hydrozoans comprising the family Porpitidae

The chondrophores or porpitids are a small group of hydrozoans in the family Porpitidae. Though it derives from an outdated name for this lineage, some still find the term 'chondrophore' useful as a synonym to 'porpitid' in discussions of the two genera contained therein, Porpita and Velella.

<i>Velella</i> Species of cnidarian

Velella is a monospecific genus of hydrozoa in the Porpitidae family. Its only known species is Velella velella, a cosmopolitan free-floating hydrozoan that lives on the surface of the open ocean. It is commonly known by the names sea raft, by-the-wind sailor, purple sail, little sail, or simply Velella.

<i>Gonionemus</i> Genus of hydrozoans

Gonionemus is a genus of hydrozoans that uses adhesive discs near the middle of each tentacle to attach to eelgrass, sea lettuce, or various types of algae instead of swimming. They are small and hard to see when hanging onto swaying seaweed. Nevertheless, they are capable of swimming when necessary. The bell is transparent, revealing the four orange to yellowish-tan gonads that lie along most of the length of the four radial canals. The pale yellow manubrium has four short, frilly lips. Up to 80 tentacles line the bell margin, with about an equal number of statocysts. Copepods are a favored prey.

<span class="mw-page-title-main">Medusozoa</span> Clade of marine invertebrates

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.

<i>Turritopsis dohrnii</i> Species of small, biologically immortal jellyfish

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.

<span class="mw-page-title-main">Hydroidolina</span> Subclass of hydrozoans

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.

<span class="mw-page-title-main">Leptothecata</span> Order of cnidarians with hydrothecae

Leptothecata, or thecate hydroids, are an order of hydrozoans in the phylum Cnidaria. Their closest living relatives are the athecate hydroids, which are similar enough to have always been considered closely related, and the very apomorphic Siphonophorae, which were placed outside the "Hydroida". Given that there are no firm rules for synonymy for high-ranked taxa, alternative names like Leptomedusa, Thecaphora or Thecata, with or without the ending emended to "-ae", are also often used for Leptothecata.

<span class="mw-page-title-main">Conica (suborder)</span> Suborder of hydrozoans

Conica are a cnidarian suborder of the Leptomedusae. They make up the bulk of their order; their internal relationships are not well resolved, and most of the roughly 30 families are not yet assigned to a superfamily.

<span class="mw-page-title-main">Trachylinae</span> Subclass of hydrozoans

Trachylinae is a subclass of hydrozoans. It is placed at order rank in many older classifications, and limited to contain the Narcomedusae, Trachymedusae, the Actinulidae, then considered an independent order, and also the Limnomedusae which were traditionally placed in the paraphyletic "Hydroida". It is not entirely clear whether the Limnomedusae and the Trachymedusae as conventionally circumscribed are monophyletic

<span class="mw-page-title-main">Narcomedusae</span> Order of hydrozoans

Narcomedusae is an order of hydrozoans in the subclass Trachylinae. Members of this order do not normally have a polyp stage. The medusa has a dome-shaped bell with thin sides. The tentacles are attached above the lobed margin of the bell with usually a gastric pouch above each. There are no bulbs on the tentacles and no radial canals. Narcomedusans are mostly inhabitants of the open sea and deep waters. They can be found in the Mediterranean in large numbers.

<i>Eudendrium ramosum</i> Species of hydrozoan

Eudendrium ramosum, sometimes known as the tree hydroid, is a marine species of cnidaria, a hydroid (Hydrozoa) in the family Eudendriidae of the order Anthoathecata.

<i>Solanderia</i> Genus of hydrozoans

Solanderia is the sole genus of hydrozoans in the monotypic family Solanderiidae. They are commonly known as tree hydroids or sea fan hydroids.

Jean Bouillon was a Belgian marine biologist and expert on Hydrozoa.

<i>Porpita prunella</i> Species of hydrozoan

Porpita prunella is a marine species of hydrozoan organisms within the family Porpitidae. It consists of colonies of zooids. Very little is known about this species, as there have been no confirmed sightings since its discovery in 1801 and naming by Haeckel in 1888. Being in the chondrophore group, it is likely that its behaviour is similar to the other species of the genera in the family. However there are also serious doubts as to its very existence as a separate species and may in fact be a synonym for Porpita porpita instead.

<span class="mw-page-title-main">Capitata</span> Suborder of hydrozoans

Capitata is a suborder of Hydrozoa, a class of marine invertebrates belonging to the phylum Cnidaria.

<span class="mw-page-title-main">Filifera</span> Suborder of hydrozoans

Filifera is a suborder of hydrozoans in the order Anthoathecata. They are found in marine, brackish and freshwater habitats.

<i>Clava multicornis</i> Genus of hydrozoans

Clava is a monotypic genus of hydrozoans in the family Hydractiniidae. It contains only one accepted species, Clava multicornis. Other names synonymous with Clava multicornis include Clava cornea, Clava diffusa, Clava leptostyla, Clava nodosa, Clava parasitica, Clava squamata, Coryne squamata, Hydra multicornis, and Hydra squamata. The larvae form of the species has a well developed nervous system compared to its small size. The adult form is also advanced due to its ability to stay dormant during unfavorable periods.

<span class="mw-page-title-main">Zancleidae</span> Family of cnidarians

Zancleidae is a family of cnidarians belonging to the order Anthoathecata.

Tima nigroannulata, commonly known as the elegant jellyfish, is a recently discovered colonial hydrozoa found on the Pacific coast of Japan.

References

  1. ↑ Schuchert, P. (2014). Anthoathecata. Accessed through: Schuchert, P. (2014) World Hydrozoa database at http://www.marinespecies.org/hydrozoa/aphia.php?p=taxdetails&id=13551 on 2014-10-31
  2. 1 2 Bouillon, J.; Gravili, C.; Pagès, F.; Gili, J.-M.; Boero, F. (2006). An introduction to Hydrozoa. Mémoires du Muséum national d'Histoire naturelle, 194. Muséum national d'Histoire naturelle: Paris, France. ISBN   2-85653-580-1. 591pp. + 1 cd-rom
  3. ↑ Collins, A. G., Winkelmann, S., Hadrys, H. and Schierwater, B. (2005), Phylogeny of Capitata and Corynidae (Cnidaria, Hydrozoa) in light of mitochondrial 16S rDNA data. Zoologica Scripta, 34: 91–99. doi:10.1111/j.1463-6409.2005.00172.x
  4. ↑ Schuchert (2014), World Hydrozoa database.
  5. ↑ New name is required for the remaining Tubulariida, because Tubulariidae has been moved to Aplanulata.

Bibliography

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