| Amphiodia pulchella | |
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| Species: | A. pulchella |
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| Amphiodia pulchella (Lyman, 1869) [1] | |
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Amphiodia pulchella is a species of brittle star belonging to Amphiuridae, a diverse family of the Ophiurida order.
This species has an echinoderm body plan with a central disk and five arms used for locomotion. A. pulchella is composed of a calcium carbonate skeleton and a series of vessels used to move water throughout the body. This species also has tube feet with no suction cups that are used for feeding and sensing the surrounding environment rather than locomotion. [2] Instead, they move by twisting their arms and using nearby objects to propel themselves forward. [3] Amphiodia pulchella are typically a gray or reddish brown color with fine scales covering the central disc. A.pulchella typically burrow their central disc beneath soft sediment. One or two arms will be within the burrow and the remaining arms are exposed. [4] For ventilation, one or two of the arms will undulate within the burrow. A.pulchella will also reinforce their burrows with a layer of mucus to ensure that it can withstand the harsh conditions of a marine environment. [5] Adults reach a maximum central disk size of about 5 mm with arms that are 40-50mm. A. pulchella have proximally separated adoral shields with arm spines. The short medial spine is dorsoventrally flattened and covered in spines. The remaining arm spines are round and blunt. [6] At the apex of the jaw, there are two infradental papillae followed by a single row of square teeth. [7] A unique feature of specimens in the Ophiuroidea class is the ability to regenerate body parts. If an arm is separated from the central disc of a brittle star, the organism can regenerate this limb. This ability is particularly useful in escaping predation. Ophiuroidea are also unique compared to other echinoderms because they have a smaller coelom and a nerve ring in the central disc that is connected to each arm. Furthermore, this species uses the epidermis to sense light and other factors of the surrounding environment as they do not have eyes nor a brain. [2]
Brittle stars have little interaction with humans as they are not a prominent part of marine commerce. However, they are a key part of the food chain in reef ecosystems. Brittle stars are prey to a variety of crustaceans and fish. The main source of food for this species is detritus. [2] Although they do not often come in contact with humans they are still affected by human activity. Climate change, which is mostly a result of human activity releasing green house gases into the atmosphere, is causing ocean water to increase in acidity. It was recently reported that the acidic water is increasing the rate of calcification in brittle stars. Brittle stars are producing shells at a greater rate to protect their delicate arms from being compromised by acidic water while they are burrowed. This comes at a great metabolic cost and can paralyze brittle stars within their burrow, often resulting in fatality. [8]
Oocytes 0.65mm in diameter suggest that A.pulchella have a planktonic, feeding larval stage and do not rely on yolk reserves for development. [9] The reproductive organs of this species are small in size and located at the bursal slit. At this slit, respiration is facilitated by circulating water. At the same time, gametes can also be released for reproduction or retained as broods. [10]
A. pulchella typically burrow into sediment at a depth range of 1-71 m and frequent reef environments. Geographically, this species can be found in the Western Central Atlantic including the coasts of Florida, Mexico, Cuba, Jamaica, Puerto Rico, Tobago, Belize, Brazil, and Argentina. [11] Amphiodia pulchella thrive under mesohaline conditions with DO ≥2.0 ml L-1. [12]
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.
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.
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.
Ophiothrix suensoni, Suenson's brittle star or the sponge brittle star, is a species of marine invertebrate in the order Ophiurida. It is found in the Caribbean Sea and Gulf of Mexico. It is included in the subgenus Acanthophiothrix making its full scientific name Ophiothrix (Acanthophiothrix) suensoni.
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.
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.
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.
Gorgonocephalus arcticus is a species of basket star in the class Ophiuroidea. The genus name comes from the Greek, gorgós meaning "dreaded" and cephalus meaning "head", and refers to the similarity between these echinoids and the Gorgon's head from Greek myth with its coiled serpents for hair.
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).
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.
Ophiopholis aculeata, the crevice brittle star or daisy brittle star, is a species of brittle star in the family Ophiactidae. It has a circum-polar distribution and is found in the Arctic Ocean, the northern Atlantic Ocean and the northern Pacific.
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.
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.
Ophiohamus is a genus of brittle stars in the family Ophiacanthidae from New Caledonia. Timothy D. O'Hara and Sabine Stöhr circumscribed and named the genus in 2006; they described the type species Ophiohamus nanus in the same work. A second species, Ophiohamus georgemartini, was described by O'Hara and Caroline Harding in 2015. As of 2018, those are the only two species recognized in this genus.
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).
Amphiodia occidentalis or 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, 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.
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.
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.
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