Amphiodia occidentalis

Last updated

Amphiodia occidentalis
Long-armed Brittle Star (Amphiodia occidentalis).jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Echinodermata
Class: Ophiuroidea
Order: Ophiurida
Family: Amphiuridae
Genus: Amphiodia
Species:
A. occidentalis
Binomial name
Amphiodia occidentalis
(Lyman, 1860) [1]

Amphiodia occidentalis, the long-armed brittle star, is a species of brittle star belonging to the family Amphiuridae. It is found in the Eastern Pacific coast from Alaska to USA, [2] often on the seafloor within intertidal and subtidal zones. Within these areas, it is often found buried a few centimeters under the sand with 2 or 3 arms extending through the surface. [3]

Contents

Description

Amphiodia occidentalis exhibit pentaradial symmetry characteristic of brittle stars. They contain a flat disc body which can measure up to 11 mm in diameter [4] that contains their organs. [5] Five long, segmented arms at least eight times the diameter of the disc extend from the body which are covered in flattened spines [6] and tube feet. [7]

Additionally, they have a calcium carbonate endoskeleton composed of calcareous ossicles. [7] Their central nervous system is highly metameric with the same pattern of peripheral nerves repeated in each arm. [8]

Locomotion

Instead of using their tube feet for locomotion, Amphiodia occidentalis and several other brittle star species use their arms to crawl along the substrate. [9]

Despite their radial symmetry, they move using bilaterally symmetrical locomotion. [9] Since they lack a locomotor anterior, they achieve this type of locomotion by employing two techniques: rowing and reverse rowing. [9] The most common technique is the rowing technique, in which the center limb is in the front, towards the direction of movement, with the other limbs helping to move in the direction of the center limb. In reverse rowing, the center limb drags in the back, the opposite direction of movement, as the other limbs propel away from the center limb. In both techniques, the designated right and left forelimbs are highly synchronized while the hind limbs present greater variability. [7] When changing directions, the disc does not rotate. Depending on the new direction, they designate the appropriate limb as the center limb and designate new identities to the other limbs corresponding to their position to the central limb. Rowing or reverse rowing is then utilized to move according to the new center limb. [9]

Diet

Amphiodia occidentalis are facultative detritivores, mainly eating detritus on the seafloor [5] [3] but can feed in other ways. By using their tube feet to catch food particles, they also engage in suspension feeding. [7]

Reproduction

Amphiodia occidentalis has separate sexes and are broadcast spawners, [10] releasing their eggs and sperm into the water column where fertilization and larval development occurs as plankton [11] Their breeding cycles are periodic with higher rates of spawning activity in the winter and spring. [10]

Life stages

Fertilized eggs of Amphiodia occidentalis are spherical, negatively buoyant, and surrounded by a thick hyaline layer and a fertilization envelope. [7] The larvae exhibit bilateral symmetry but lack other characteristic structures of ophiopluteus larva (such as cilia, larval arms, paired larval spicules) setting them apart from other brittle stars. [7] When they hatch out of the fertilization envelope as juveniles, they exhibit pentamerous radial symmetry. They also remain immotile for five days as they lack cilia and developed podia. [7] At day eight after fertilization, they can use their podia for movement. [7] They continue to grow and develop until they reach the adult stage.

Related Research Articles

<span class="mw-page-title-main">Echinoderm</span> Exclusively marine phylum of animals with generally 5-point radial symmetry

An echinoderm is any member of the phylum Echinodermata. The adults are recognisable by their radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the sea lilies or "stone lilies". Adult echinoderms are found on the sea bed at every ocean depth, from the intertidal zone to the abyssal zone. The phylum contains about 7,000 living species, making it the second-largest grouping of deuterostomes, after the chordates. Echinoderms are the largest entirely marine phylum. The first definitive echinoderms appeared near the start of the Cambrian.

<span class="mw-page-title-main">Brittle star</span> Echinoderms, closely related to starfish

Brittle stars, serpent stars, or ophiuroids are echinoderms in the class Ophiuroidea, closely related to starfish. They crawl across the sea floor using their flexible arms for locomotion. The ophiuroids generally have five long, slender, whip-like arms which may reach up to 60 cm (24 in) in length on the largest specimens.

<span class="mw-page-title-main">Amphiuridae</span> Family of brittle stars

Amphiuridae are a large family of brittle stars of the suborder Gnathophiurina. Some species are used to study echinoderm development and bioluminescence.

Ophiocanops fugiens is a living species in the brittle star family Ophiocanopidae. Though once considered to be the only one living species in this brittle star family, recent research has brought to light three specimens of Ophiocanops that differ substantially from O. fugiens. It has been regarded as the most primitive brittle star, close to Paleozoic forms, though other authors have disagreed with the view. Classification of O. fugiens is highly argued. Ophiocanops is usually placed in the order Oegophiurida or regarded as a genus incertae sedis or even given its own subclass Oegophiuridea. Some recent data suggest its relationship to the extant family Ophiomyxidae.

<i>Amphiodia pulchella</i> Species of brittle star

Amphiodia pulchella is a species of brittle star belonging to Amphiuridae, a diverse family of the Ophiurida order.

<i>Ophiocoma scolopendrina</i> Species of brittle star

Ophiocoma scolopendrina is a species of brittle star belonging to the family Ophiocomidae. Restricted to life in the intertidal, they live in the Indo-Pacific. They can typically be found within crevices or beneath borders on intertidal reef platforms. Unlike other Ophiocoma brittle stars, they are known for their unique way of surface-film feeding, using their arms to sweep the sea surface and trap food. Regeneration of their arms are a vital component of their physiology, allowing them to efficiently surface-film feed. These stars also have the ability to reproduce throughout the year, and have been known to have symbiotic relationships with other organisms.

<i>Ophionereis reticulata</i> Species of brittle star

Ophionereis reticulata, the reticulated brittle star, is a brittle star in the family Ophionereididae. It is found in shallow parts of the western Atlantic, Caribbean Sea and Gulf of Mexico.

<i>Amphiura filiformis</i> Species of brittle star

Amphiura filiformis is a species of brittle star belonging to the family Amphiuridae. It is found on the seabed in the north east Atlantic Ocean and adjoining seas to a depth of 200 metres (660 ft). It digs itself a shallow burrow in the sand and waves its arms in the water above to suspension feed on plankton.

<i>Amphipholis squamata</i> Species of brittle star

Amphipholis squamata, common names brooding snake star and dwarf brittle star, is a species complex of brittle stars in the family Amphiuridae.

<i>Amphiura chiajei</i> Species of brittle star

Amphiura chiajei is a species of brittle star belonging to the family Amphiuridae. It is found in the northeastern Atlantic Ocean and adjoining seas to a depth of 1,000 metres (3,300 ft). It digs itself into the soft sediment of the seabed and raises its arms into the water above to suspension feed on plankton. It was first described by the British naturalist Edward Forbes in 1843, and was named for the Italian zoologist Stefano Delle Chiaje (1794–1860).

<i>Ophiocoma echinata</i> Species of brittle star

Ophiocoma echinata, the spiny ophiocoma, is a species of brittle star belonging to the family Ophiocomidae. It is the type species of the genus Ophiocoma and is found in the tropical west Atlantic Ocean, the Caribbean Sea and the Gulf of Mexico.

<i>Ophiactis savignyi</i> Species of brittle star

Ophiactis savignyi is a species of brittle star in the family Ophiactidae, commonly known as Savigny's brittle star or the little brittle star. It occurs in the tropical and subtropical parts of all the world's oceans and is thought to be the brittle star with the most widespread distribution. It was first described by the German zoologists Johannes Peter Müller and Franz Hermann Troschel in 1842. The specific name honours the French zoologist Marie Jules César Savigny.

Ophiacanthidae is a family of brittle stars. Axel Vilhelm Ljungman circumscribed this taxon in 1867; he initially named the subfamily Ophiacanthinae within the family Amphiuridae. Gordon L. J. Paterson promoted its rank to family in 1985.

<i>Astrobrachion adhaerens</i> Species of brittle star

Astrobrachion adhaerens is a basket star in the Euryalidae family. Along with A. constrictum, it is one of only two species in the genus Astrobrachion. Both species live in association with soft corals in moderately deep water. It is endemic to the west, north and east coasts of Australia, the Kermadec Islands and Lord Howe Island.

<i>Acrocnida</i> Genus of echinoderms

Acrocnida is a genus of brittle stars in the family Amphiuridae. The genus contains three members: Acrocnida brachiata, Acrocnida semisquamata, and Acrocnida spatulispina. There has also been observed hybridization between both Acrocnida brachiata and Acrocnida spatulispina. It is a fairly common genus, usually found along the coasts of Northwestern Europe, but with some species like semisquamata appearing around West Africa. Members of this genus primarily prefer intertidal and sub-tidal habitats, and they are they are less likely to be found in intertidal areas by comparison. This genus was not officially classified until 1926, by T. Gislén. One study found that due to the increased calcification that Acrocnida brachiata causes could be a potential source of Carbon Dioxide for not only the warm, shallow environments they live in, but also for the atmosphere.

Acrocnida brachiata, the sand burrowing brittlestar, is a species of brittle star in the family Amphiuridae. It occurs on the seabed in the northeastern Atlantic Ocean and the North Sea, living semi-buried in the sand with only its arm tips projecting.

Amphiodia urtica, commonly known as the burrowing brittle star or the long arm brittle star, is a species of brittle star belonging to the family Amphiuridae. It is found on the Pacific coast of North America at depths down to about 370 m (1,200 ft).

<i>Ophiocomella alexandri</i> Species of brittle star

Ophiocomella alexandri, known as Alexander's spiny brittle star or banded brittle star, is a species of marine brittle star. It was first described to science by Theodore Lyman in 1860. Lyman states in his description that the animal is named for his friend, Alexander E. R. Agassiz, the son of Lyman's mentor, Louis Agassiz.

<i>Ophiomusa</i> Genus of echinoderms

Ophiomusa is a genus of echinoderms belonging to the family Ophiolepididae that includes: sea urchins, sand dollars and sea cucumbers. Ophiurida are similar to starfish; they both have a central disc and five arms sprouting from the disc. One of the main distinguishing factors of an Ophiuroid is its arms; the arms of an Ophiurida are longer, thinner, and distinctly separated in comparison to those of a sea star.

<span class="mw-page-title-main">Ophiothela mirabilis</span> Species of echinoderm

Ophiothela mirabilis is a species of ophiuroid brittle stars within the family Ophiotrichidae. O. mirabilis is an epizoic species which have a non-parasitic relationship with host sponges or gorgonians. Although native to the Pacific Ocean, it has invaded the Caribbean and southwestern Atlantic since late 2000. Many of its characteristics, including reproduction and diet, allow O. mirabilis opportunities to quickly propagate and spread through habitats.

References

  1. ↑ Stöhr, Sabine (2012). Stöhr S, O'Hara T (eds.). "Amphiodia occidentalis (Lyman, 1860)". World Ophiuroidea database. World Register of Marine Species . Retrieved 2012-10-16.
  2. ↑ "Amphiodia occidentalis, long-armed brittle star". Search SeaLifeBase. Retrieved 2021-02-11.
  3. 1 2 Fager, Edward W. (1968). "A Sand-Bottom Epifaunal Community of Invertebrates in Shallow Water". Limnology and Oceanography. 13 (3): 448–464. doi:10.4319/lo.1968.13.3.0448. ISSN   0024-3590. JSTOR   2833737.
  4. ↑ "Robert H. Morris, Donald P. Abbott & Eugene C. Haderlie, 1980. Intertidal Invertebrates of California: xi + 690 pp., 6 maps, 200 coloured plates. Stanford University Press, Stanford, California, U.S.A. ISBN 0-8047-1045-7. Price $U.S. 30.00". Crustaceana. 41 (3): 319. 1981. doi:10.1163/156854081x00930. ISSN   0011-216X.
  5. 1 2 Burgess, Dany (March 18, 2018). "The brittle stars embody nature's fragility...and resilience". Washington State Department of Ecology.
  6. ↑ Lyman, T (1860). "Descriptions of new Ophiuridae, belonging to the Smithsonian Institution and to the Museum of Comparative Zoölogy at Cambridge". Proceedings of the Boston Society of Natural History. 7: 193–204. doi: 10.5962/bhl.part.4822 . ISSN   0270-2444.
  7. 1 2 3 4 5 6 7 8 Emlet, Richard B. (2006-06-01). "Direct development of the brittle star Amphiodia occidentalis (Ophiuroidea, Amphiuridae) from the northeastern Pacific Ocean". Invertebrate Biology. 125 (2): 154–171. doi:10.1111/j.1744-7410.2006.00049.x.
  8. ↑ Zueva, Olga; Khoury, Maleana; Heinzeller, Thomas; Mashanova, Daria; Mashanov, Vladimir (2018). "The complex simplicity of the brittle star nervous system". Frontiers in Zoology. 15 (1): 1. doi: 10.1186/s12983-017-0247-4 . ISSN   1742-9994. PMC   5796562 . PMID   29434647.
  9. 1 2 3 4 Astley, Henry C. (2012-06-01). "Getting around when you're round: quantitative analysis of the locomotion of the blunt-spined brittle star, Ophiocoma echinata". Journal of Experimental Biology. 215 (11): 1923–1929. doi: 10.1242/jeb.068460 . ISSN   1477-9145. PMID   22573771. S2CID   11314014.
  10. 1 2 Rumrill, Steven S.; Pearse, John S. (1985), "Contrasting reproductive periodicities among north-eastern Pacific ophiuroids", Echinodermata, CRC Press, doi:10.1201/9781003079224-137, ISBN   978-1-003-07922-4, S2CID   225438754 , retrieved 2022-04-24
  11. ↑ Stöhr, Sabine; O'Hara, Timothy D.; Thuy, Ben (2012-03-02). Laudet, Vincent (ed.). "Global Diversity of Brittle Stars (Echinodermata: Ophiuroidea)". PLOS ONE. 7 (3): e31940. doi: 10.1371/journal.pone.0031940 . ISSN   1932-6203. PMC   3292557 . PMID   22396744.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.