Mertensia ovum | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Ctenophora |
Class: | Tentaculata |
Order: | Cydippida |
Family: | Mertensiidae |
Genus: | Mertensia Lesson, 1830 |
Species: | M. ovum |
Binomial name | |
Mertensia ovum (Fabricius, 1780) | |
Synonyms | |
Genus synonymy
Species synonymy
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Mertensia ovum, also known as the Arctic comb jelly or sea nut, is a cydippid comb jelly or ctenophore first described as Beroe ovum by Johan Christian Fabricius in 1780. It is the only species in the genus Mertensia. Unusually among ctenophores, which normally prefer warmer waters, it is found in the Arctic and adjacent polar seas, mostly in surface waters down to 50 metres (160 ft). [1] [2]
In addition to being weakly bioluminescent in blues and greens, comb jellies produce a rainbow effect similar to that seen on an oil slick, and which is caused by interference of incident light on the eight rows of moving cilia or comb rows which propel the organism. The comb rows beat sequentially, rather like the action of a Mexican wave. The comb rows also function as chemical sense organs, serving the same role as insect antennae. M. ovum is the major source of bioluminescence from Arctic gelatinous zooplankton. [3]
This species, like other ctenophores, has a large body cavity and is carnivorous, feeding on copepods and small crustaceans snagged by its two extremely sticky and robust tentacles (see Tentaculata). These are long and contractile with numerous lateral tentillae or side branches bearing colloblasts, each of which consists of a coiled spiral filament, structurally similar to a nematocyst, but instead of injecting a toxin, release an adhesive substance which ensnares the prey. [4] These tentacles can be retracted into a tentacle sheath. The body is on the whole light pink in colour, oval in the tentacular plane and considerably compressed in the sagittal plane. Its unconventional brain consists of a network of nerves arranged under its outer skin. [5]
A study in the Barents Sea found that it ingests prey ranging from small copepods to amphipods and krill, but that its staple diet consists of large copepod species such as Calanus finmarchicus , C. glacialis , C. hyperboreus and Metridia longa . [6]
Like garden snails, Mertensia is hermaphroditic, reproducing sexually and occasionally asexually. Eggs and sperm are ejected into the water and from the fertilized eggs ovoid larvae develop. The planktonic larvae of this species are 2–3 millimetres (0.08–0.12 in) long while adults grow up to 10 centimetres (3.9 in). [7] In the Baltic sea its population is solely consisting of sexual active larvae [8]
The genus name Mertensia commemorates the German naturalist Karl Heinrich Mertens aka Andrei Karlovich Mertens (17 May 1796 – 18 September 1830). Mertens accompanied the Russian naturalist Alexander Philipov Postels aboard the Senyavin in 1826 on a voyage to "reconnoitre and describe the coasts of Kamchatka, the land of the Chuchkis and the Koriaks (the coasts of which have not yet been described by anyone, and which are unknown except by the voyage of Captain Bering); the coasts of the Okhotsk Sea, and the Shantar Islands, which although they are known to us, have not been sufficiently described."
Ctenophora comprise a phylum of marine invertebrates, commonly known as comb jellies, that inhabit sea waters worldwide. They are notable for the groups of cilia they use for swimming, and they are the largest animals to swim with the help of cilia.
Tentaculata is a class of comb jellies, one of two classes in the phylum Ctenophora. The common feature of this class is a pair of long, feathery, contractile tentacles, which can be retracted into specialised ciliated sheaths. In some species, the primary tentacles are reduced and they have smaller, secondary tentacles. The tentacles have colloblasts, which are sticky-tipped cells that trap small prey.
Beroidae is a family of ctenophores or comb jellies more commonly referred to as the beroids. It is the only family within the monotypic order Beroida and the class Nuda. They are distinguished from other comb jellies by the complete absence of tentacles, in both juvenile and adult stages. Species of the family Beroidae are found in all the world's oceans and seas and are free-swimmers that form part of the plankton.
Lobata is an order of Ctenophora in the class Tentaculata with smaller tentacles than other ctenophores, and distinctive flattened lobes extending outwards from their bodies.
Mnemiopsis leidyi, the warty comb jelly or sea walnut, is a species of tentaculate ctenophore. It is native to western Atlantic coastal waters, but has become established as an invasive species in European and western Asian regions. Three species have been named in the genus Mnemiopsis, but they are now believed to be different ecological forms of a single species M. leidyi by most zoologists.
Chrysaora colorata (Russell), commonly known as the purple-striped jelly, is a species of jellyfish that exists primarily off the coast of California from Bodega Bay to San Diego. The bell (body) of the jellyfish is up to 70 cm (2.3 ft) in diameter, typically with a radial pattern of stripes. The tentacles vary with the age of the individual, consisting typically of eight marginal long dark arms, and four central frilly oral arms. It is closely studied by scientists due to not much being known about their eating habits. A 15-foot-long specimen has been seen.
Cydippida is an order of comb jellies. They are distinguished from other comb jellies by their spherical or oval bodies, and the fact their tentacles are branched, and can be retracted into pouches on either side of the pharynx. The order is not monophyletic, that is, more than one common ancestor is believed to exist.
Platyctenida is an order of comb jellies.
Pleurobrachia bachei is a member of the phylum Ctenophora and is commonly referred to as the Pacific sea gooseberry. These comb jellies are often mistaken for medusoid Cnidaria, but lack stinging cells.
The benthic comb jelly is a comb jelly living in the Ryukyu Trench near Japan. Found at a depth of 7,217 metres (23,700 ft), it is the deepest dwelling ctenophore discovered.
Beroe ovata is a comb jelly in the family Beroidae. It is found in the South Atlantic Ocean and the Mediterranean Sea and has been introduced into the Black Sea, the Aegean Sea, the Sea of Azov and the Caspian Sea. It was first described by the French physician and zoologist Jean Guillaume Bruguière in 1789.
Bolinopsis infundibulum, commonly known as the common northern comb jelly, is a species of comb jelly in the family Bolinopsidae. It is found in the northern Atlantic Ocean and was first described by the Danish naturalist Otto Friedrich Müller in 1776.
Pleurobrachia pileus is a species of comb jelly, commonly known as a sea gooseberry. It is found in open water in the northern Atlantic Ocean, the North Sea, the Baltic Sea and the Black Sea, and was first described by the Danish zoologist Otto Friedrich Müller in 1776.
Thalassocalyce is a genus of ctenophore, or comb jellies, known from the California Coast, Gulf of Mexico, and west north Atlantic. It is represented by a single species, Thalassocalyce inconstans, which is the only species in the family Thalassocalycidae and the order Thalassocalycida. T. inconstans is a pelagic ctenophore typically occurring in upper-mesopelagic depths, but has been observed at depths up to 3,500 m in Monterey Canyon.
Poralia is a genus of jellyfish in the family Ulmaridae. It is a monotypic genus containing a single species, Poralia rufescens. This jellyfish is pelagic, and is found in deep water in most of the world's oceans.
Beroe abyssicola is a species of beroid ctenophore, or comb jelly. It is largely found in deep waters in the North Pacific Ocean, and is common in Japan and the Arctic Ocean. A predator, Beroe feeds mostly on other ctenophores by swallowing them whole. Like other ctenophores, B. abyssicola has a simple nervous system in the form of a nerve net, which it uses to direct its movement, feeding, and hunting behaviors.
Duobrachium is a monotypic genus of comb jellies belonging to the order Cydippida, family unknown. The only species is Duobrachium sparksae.
Euplokamis is a genus of ctenophores, or comb jellies, belonging to the monotypic family Euplokamididae. Despite living for hundreds of millions of years in marine environments, there is minimal research regarding Euplokamis, primarily due to their body structure. Research on the evolution of the basic body structures of diploblastic metazoans revealed that there are four major phyla, including the Ctenophores. Although the morphology of Euplokamis often resembles the medusa stage of Cnidarians, their eight rows of combs are one distinguishing feature that led to the official classification of Ctenophores. After being originally described by Chun (1879), the family Euplokamididae was expanded by Mills (1987) due to the discovery of a new species, Euplokamis dunlapae. Further research indicated that Euplokamis should be identified from Mertensiidae due to the rows of combs and some compression. They may also be distinguished from the genus Pleurobrachia due to their more elongated shape. Additionally, various adaptations of Euplokamis have been observed such as the use of tentacles for movement/feeding, a complex nervous system, and bioluminescent capabilities. Other characteristics including a defined mesoderm, lack of stinging cells, developmental differences, and symmetry supported the reclassification of these organisms.
Beroe gracilis is a species of comb jelly in the family Beroidae. It is a free-swimming species found in the North Sea, the Atlantic Ocean and the Mediterranean Sea.
Callianira antarctica is a species of ctenophore that physically resembles Mertensia ovum, but lacks the oil sacs. Just like other ctenophores, over 95% of its body mass and composition is water.
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