Eulagisca gigantea | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Annelida |
Clade: | Pleistoannelida |
Subclass: | Errantia |
Order: | Phyllodocida |
Family: | Polynoidae |
Genus: | Eulagisca |
Species: | E. gigantea |
Binomial name | |
Eulagisca gigantea Monro, 1939 [1] | |
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[ citation needed ].
The scale worms have been believed to be descendants of a different species that invaded the deep-sea millions of years ago. [2] The species then diverged to colonize different habitats including chemosynthesis-based habitats across the five oceans. [2]
The Polynoidae family has been found in intertidal waters to the deep sea. [2] They have also been found in chemosynthesis-based habitats, like hydrothermal vents, anchialine caves, cold seeps, and more. [2] To survive in these extreme habitats, some species of scale worms have morphological and molecular adaptations that allow them to survive there. [2] Some deep-sea Polynoidae members are known to live in association with megafauna like black coral. [3] Other species are also shown to have a symbiotic relationship with a carnivorous sponge. [4]
Polynoidae is a monophyletic group and within it, there are paraphyletic groups. [5] The family Polynoidae is the most species-rich family of the scale worms, ranging from bioluminescence worms to transparent worms. [6] The bioluminescence comes from the enzyme polynoidin that is within the scales of the worm. [7] This family has around 900 species in it. [8] Within the genus Eulagisca there are 5 different species known: Eulagisca corrientis, Eulagisca macnabi, Eulagisca puschkini, Eulagisca uschakovi, and Eulagisca gigantea.
Eulagisca gigantea is one of the largest scale worms getting up to 20 centimeters in size. The scale worms are characterized by their body segment amount. They can get up to 40 segments with around 15 pairs of elytra on each segment. [8] Their bodies are large and flattened. The elytra are the scales that are attached to the segments. The scale arrangement is an important character in identifying the species of scale worm. [5] Most scales are oriented in an alternating overlapping pattern. Eulagisca gigantea is seen to have cream color scales with the parapodia being a golden brown. This golden-colored parapodia is how the Eulagisca gigantea is able to be distinguished from other Eulagisca and scale worms. On the prostomium, there are three antennae used for mechanosensory. [9] They also have two pairs of eyes. [8] The eyes appear dorsally on the head portion and are sessile. [10] On the posterior margin of the prostomium is a nuchal organ with cilia bands on it. [11] The retractable proboscis consists of a pair of large jaws used for grasping prey while hunting.
They have a thick muscular pharynx used to help digest their prey. [12] They need this muscular pharynx to help break down the prey since they are predatory. There are also some species that feed on bacterial mats. [10]
While scale worms are benthic and spend most of their time on the floor of the ocean, they are also able to swim. [13] When the scale worms stop swimming, they mostly sink to the floor of the ocean while some others may remain suspended in the water column. [13] They are able to swim, but the length of their cirri and body are critical to the time they are able to swim. If they are a bigger scale worm, they will struggle to swim for longer times. [13] They swim by the antagonistic contraction of the longitudinal body muscles and the movement of parapodia. [13] The movement of the parapodium has two different strokes, the power stroke and the recovery stroke. The power strokes are thrusts that gain movement directed from head to tail while the recovery strokes are movements directed from tail to head. [13]
Eulagisca gigantea most likely uses a similar respiratory, circulatory, nervous, and digestive system as most marine Annelids. E. gigantea will likely use gills for respiration as seen in other marine Annelids. [14] In Annelids, we see closed circulatory systems with the blood pumped through the blood vessels by muscle contraction. The nervous system of E. gigantea is likely a centralized cerebral ganglion in the prostomium with a ladder of nerves through the rest of the body. [14]
Like most Annelids, the family Polynoidae goes through indirect development with a trochophore larvae. The larvae of the Polynoidae differs from regular trochophore larvae because it lacks the metatroch and food grove. [15] After the larvae goes through metamorphosis, the juvenile scale worms start using their proboscis with jaws to feed. [15]
Most scale worms are known to have different sexes seen through different number of nephridial papillae. [16] While they do have separate sexes, sometimes hermaphroditism does occur. [17] The structures within the worm show the capability of both internal and external fertilization.
Polychaeta is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes. Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made of chitin. More than 10,000 species are described in this class. Common representatives include the lugworm and the sandworm or clam worm Alitta.
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. 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. 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.
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.
Adyte hyalina is a species of marine annelids in the family Polynoidae and the only accepted species in the genus Adyte. Adyte hyalina occurs in the North-east Atlantic Ocean and Mediterranean Sea, at depths down to about 150 metres.
Lepidasthenia is a genus of marine Polychaete worms belonging to the family Polynoidae. Species of Lepidasthenia are found worldwide to depths of about 1200 m but are more common in shallower water.
Eunoe is a genus of marine annelids in the family Polynoidae. The genus includes 48 species which are found world-wide, mostly from depths of 50 m or more.
Eunoe leiotentaculata is a scale worm known from southern Australia and New Zealand and the South Pacific Ocean at depths of 500–1200 m.
Acanthicolepis is a genus of marine annelids in the family Polynoidae. The genus was described in 1990 and includes two short-bodied species with up to 50 segments and which occur in the Mediterranean Sea and North-east Atlantic Ocean.
Australaugeneria is a genus of marine annelids in the family Polynoidae. The genus includes 4 species which are commensal on octocorals.
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.
Bathyadmetella is a genus of marine annelids in the family Polynoidae. The only species in the genus, Bathyadmetella commando, is known from a single specimen collected at 1646m in the north-west Pacific Ocean.
Benhamipolynoe is a genus of marine annelids in the family Polynoidae. The genus is known from the Pacific and Atlantic Oceans and includes 2 species.
Parahololepidella is a genus of marine annelids in the family Polynoidae. The genus contains a single species, Parahololepidella greeffi, This species is known from the east equatorial Atlantic Ocean and Cape Verde Islands at a maximum depth of 30m.
Polyeunoa is a genus of marine annelids in the family Polynoidae. The genus contains two species, one from the Indian Ocean and the other widespread in the south-west Atlantic ocean and the Southern Ocean.
Eulagisca macnabi is a scale worm that occurs in the Antarctic Ocean, the Amundsen Sea and off the South Orkney Islands at depths of about 300 to 1500m.
Bylgides is a genus of marine annelids in the family Polynoidae. The genus contains 9 species, all found in the Northern Hemisphere and from shallow inshore waters to depths of about 5000 m.
Pareulagisca is a genus of marine annelids in the family Polynoidae. The genus contains a single species, Pareulagisca panamensis, known from a single specimen, collected intertidally in Panama in the Pacific Ocean.
Gattyana is a genus of marine annelids in the family Polynoidae. The genus includes 11 species, 9 of which occur in the northern hemisphere, the remaining two are from the Indian Ocean off Mozambique and the Southern Ocean off New Zealand. Species of Gattyana are known from shallow water down to depths of about 1200 m.
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.
Bathynoe is a genus of marine annelids in the family Polynoidae. The genus includes two species, both known from depths of about 5000 m.