Polynoidae | |
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Dorsal view of Lepidonotus oculatus , a polynoid specimen from the Museums Victoria collection. | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Annelida |
Clade: | Pleistoannelida |
Subclass: | Errantia |
Order: | Phyllodocida |
Suborder: | Aphroditiformia |
Family: | Polynoidae |
Genera | |
See text |
Polynoidae is a family of marine Polychaete worms known as "scale worms" due to the scale-like elytra on the dorsal surface. Almost 900 species are currently recognised belonging to 9 subfamilies and 167 genera. [1] They are active hunters, but generally dwell in protected environments such as under stones. The group is widely distributed from shallow intertidal waters to hadal trenches. [2] They are the most diverse group of polychaetes in terms of genus number and second most diverse in terms of species number which is almost 8% of all segmented worm species. [1]
Most Polynoidae species are short and flattened, but can reach as much as 20 cm in length and 10 cm width in Eulagisca gigantea and Eulagisca uschakovi . Individuals are usually covered almost entirely by elytra, which can be shed and regenerated in many species. The elytra of some species are faintly bioluminescent, and leave glowing traces around the mouthparts of their predators, making those predators more likely to be attacked in turn. [3]
The first deep-sea species of Polynoidae was collected at 1230 m during the Challenger Expedition and a number of subfamilies appear to be restricted to the deep sea below 500 m. [2] Species have colonised submarine caves and hydrothermal vents. Deep sea species are characterised by a partial or complete loss of antennae, fewer segments, a reduction in jaws and delicate elytra. [2] [4]
The Polynoidae has been shown to be monophyletic, [5] however relationships within the family are unclear and hence the number of valid subfamilies has been repeatedly revised in recent years. One of the main deep sea subfamilies, the Macellicephalinae has been consistently recovered as paraphyletic, [6] and it has been proposed that ten Polynoid subfamilies could be synonymized with it to create a homogeneous clade characterised by a lack of lateral antennae. [2] More recently, however, one of the synonymized subfamilies was reinstated. [4]
The following Polynoidae genera are recognised as valid as of June 2020: [1]
Phyllodocida is an order of polychaete worms in the subclass Aciculata. These worms are mostly marine, though some are found in brackish water. Most are active benthic creatures, moving over the surface or burrowing in sediments, or living in cracks and crevices in bedrock. A few construct tubes in which they live and some are pelagic, swimming through the water column. There are estimated to be more than 4,600 accepted species in the order.
Errantia is a diverse group of marine polychaete worms in the phylum Annelida. Traditionally a subclass of the paraphyletic class Polychaeta, it is currently regarded as a monophyletic group within the larger Pleistoannelida, composed of Errantia and Sedentaria. These worms are found worldwide in marine environments and brackish water.
Pilargidae is a family of polychaetes. These marine worms are cylindrical, somewhat flattened, and can be ribbon-like. They can be found free-living on sediment, or shallowly in sediment. Some species within the genera Hermundura and Litocorsa are known to burrow, having reduced heads and parapodia. Two species are known to be commensal with other polychaetes. Pilargis berkeleyae will live in the tubes of Chaetopteridae, and Ancistrosyllis commensalis will live in Capitellidae burrows. Pilargid worms are almost all exclusively predators, classified as carnivore omnivores. They are similar in appearance to Hesionidae, with a peristomium often with two pairs of tentacular cirri, reduced or absent notopodia, and a lack of pharyngeal jaws. The first few segments bearing setigers are also somewhat fused. They can have 0 to 3 antennae, and palps. These polychaetes are rarely the most abundant polychaete.
Eulagisca is a genus of marine polychaete worms belonging to the family Polynoidae. The genus includes 5 species which are all found in the Southern and Antarctic Oceans and are notable for reaching a large size - 180 mm or more long - larger than any other species of Polynoidae.
Eulagisca gigantea is a species of scale worm. This species is specifically found in the deep-sea in cold waters like the Antarctic Ocean. The scale worms are named for the elytra on their surface that look like scales
Eunoe leiotentaculata is a scale worm known from southern Australia and New Zealand and the South Pacific Ocean at depths of 500–1200 m.
Peinaleopolynoe is a genus belonging to the family Polynoidae. Members of this genus generally live in nutrient-rich environments in the deep sea, such as whale fall, which is the reason for their name.
Eunoe ivantsovi is a scale worm known from the Tasman Sea off Lord Howe Island at a depth of 1640m.
Eulagisca uschakovi is a giant scale worm known from the Antarctic, in waters such as off Mac.Robertson Land, Palmer Archipelago and the Weddell Sea, at depths of 10 to 920m.
Eunoe tuerkayi is a scale worm described from the Mediterranean Sea at depths of about 30m.
Admetella brevis is a scale worm known from the Hjort Trench in the south-west Pacific Ocean at a depth of 5760m.
Admetella hastigerens is a scale worm known from the east Pacific Ocean at depths of about 1000–1200m.
Austropolaria is a genus of marine annelids in the family Polynoidae. The genus includes a single species, Austropolaria magnicirrata, which is known only from the Amundsen Sea in the Southern Ocean, at depths of 1000 to 1500m.
Bathyeliasona abyssicola is a deep-sea scale worm which occurs widely across the Pacific and Atlantic Oceans and over a wide depth range, from 4000m to 8000m.
Bathyeliasona kirkegaardi is a deep-sea scale worm which is only known to occur in the Pacific Ocean, where it is recorded from a depth range of about 5,500–8,000 m.
Yodanoe is a genus of marine polychaete worms belonging to the family Polynoidae, the scaleworms. Yodanoe contains a single species, Yodanoe desbruyeresi which is known from the Clarion-Clipperton Fracture Zone in the equatorial East Pacific Ocean at a depth of almost 5000 m.
Ysideria is a genus of marine polychaete worms belonging to the family Polynoidae, the scale worms. Ysideria contains a single species, Ysideria hastata which is known from the North Pacific Ocean off the coast of California at depths of about 50–60 m.
Verrucapelma nigricans is a scale worm, known from intertidal habitats in the South China Sea.
Hermadionella is a genus of marine polychaete worms belonging to the family Polynoidae, the scaleworms. Hermadionella contains 3 species which are known from the north-west Pacific and Arctic Oceans from the intertidal to depths of about 200 m.
Bruunilla nealae is a deep-sea scale worm that is known from a single specimen collected from the Clarion-Clipperton Fracture Zone in the Pacific Ocean from a depth of about 5000 m.