Limatula hodgsoni

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Limatula hodgsoni
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Bivalvia
Subclass: Pteriomorphia
Order: Limoida
Family: Limidae
Genus: Limatula
Species:L. hodgsoni
Binomial name
Limatula hodgsoni
(E. A. Smith, 1907) [1]
Synonyms
  • Lima hodgsoni E. A. Smith, 1907
  • Limatula (Antarctolima) hodgsoni (E. A. Smith, 1907)
  • Limatula closei Hedley, 1916

Limatula hodgsoni is a species of bivalve mollusc in the family Limidae, the file shells or file clams. It is native to the seas around Antarctica.

In biology, a species ( ) is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. While these definitions may seem adequate, when looked at more closely they represent problematic species concepts. For example, the boundaries between closely related species become unclear with hybridisation, in a species complex of hundreds of similar microspecies, and in a ring species. Also, among organisms that reproduce only asexually, the concept of a reproductive species breaks down, and each clone is potentially a microspecies.

Family is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy; it is classified between order and genus. A family may be divided into subfamilies, which are intermediate ranks between the ranks of family and genus. The official family names are Latin in origin; however, popular names are often used: for example, walnut trees and hickory trees belong to the family Juglandaceae, but that family is commonly referred to as being the "walnut family".

Limidae family of molluscs

The Limidae or file shells are members of the only family of bivalve molluscs in the order Limida. The family includes 130 living species, assigned to 10 genera. Widely distributed in all seas from shallow to deep waters, the species are usually epifaunal or nestling, with many species building byssal nests for protection. The majority of species are capable of irregular swimming by waving their long mantle tentacles.

Contents

Description

Limatula hodgsoni grows to a length of 27 mm (1.1 in), a height of 35 mm (1.4 in) and a diameter of 20 mm (0.8 in). The shell is white, oblong, thin, narrow above and somewhat convex; the posterior side is less curved than the anterior. The umbones are central and the ligament area is narrow and diamond-shaped. The valves are sculpted by 30 to 35 squamate ribs separated by grooves slightly narrower than the ribs. The ribs are finely marked by the annual growth lines. [2]

Bivalve shell

A bivalve shell is part of the body, the exoskeleton or shell, of a bivalve mollusk. In life, the shell of this class of mollusks is composed of two hinged parts or valves. Bivalves are very common in essentially all aquatic locales, including saltwater, brackish water, and freshwater. The shells of bivalves commonly wash up on beaches and along the edges of lakes, rivers, and streams. Bivalves by definition possess two shells or valves, a "right valve" and a "left valve", that are joined by a ligament. The two valves usually articulate with one another using structures known as "teeth" which are situated along the hinge line. In many bivalve shells, the two valves are symmetrical along the hinge line— when truly symmetrical, such an animal is said to be equivalved; if the valves vary from each other in size or shape, inequivalved. If symmetrical front-to-back, the valves are said to be equilateral, and are otherwise considered inequilateral.

Umbo (bivalve) highest part of each valve of the shell of a bivalve or univalve mollusk

The umbo is the vaguely defined, often most prominent, highest part of each valve of the shell of a bivalve or univalve mollusk. It usually contains the valve's beak, the oldest point of the valve, and its degree of prominence and its position relative to the hinge line are sometimes helpful in distinguishing bivalve taxa. The umbo forms while the animal is a juvenile, and radial growth subsequently proceeds around that area. The umbo is situated above the hinge line. In those bivalves where the umbones do not protrude, as is the case for example in some mussels, the umbones can nonetheless usually be readily identified by examining the concentric growth lines of the shell.

Distribution

Limatula hodgsoni is found on the seabed of the waters around Antarctica at depths down to at least 769 m (2,500 ft). [2] It is very common in the zone deeper than 33 m (110 ft) which is the lower limit for anchor ice formation. In some areas, this zone is characterised by a layer of sponge spicules and dead mollusc shells a metre or more thick, overgrown by living sponges. This matrix is a biodiverse habitat rich in sea anemones, polychaete worms, hydroids, bryozoans and molluscs. [3] Limatula hodgsoni is the most abundant bivalve mollusc in this habitat and is preyed on by the starfishes Odontaster validus and Diplasterias brucei . [4]

Anchor ice submerged ice anchored to a river bottom or seafloor

Anchor ice is defined by the World Meteorological Organization as "submerged ice attached or anchored to the bottom, irrespective of the nature of its formation". It may also be called bottom-fast ice. Anchor ice is most commonly observed in fast-flowing rivers during periods of extreme cold, at the mouths of rivers flowing into very cold seawater, in the shallow sub or intertidal during or after storms when the air temperature is below the freezing point of the water, and the subtidal in the Antarctic along ice shelves or near floating glacier tongues, and in shallow lakes.

Sponge spicule

Spicules are structural elements found in most sponges. They provide structural support and deter predators. Large spicules that are visible to the naked eye are referred to as megascleres, while smaller, microscopic ones are termed microscleres.

Biodiversity Variety and variability of life forms

Biodiversity refers to the variety and variability of life on Earth. Biodiversity is typically a measure of variation at the genetic, species, and ecosystem level. Terrestrial biodiversity is usually greater near the equator, which is the result of the warm climate and high primary productivity. Biodiversity is not distributed evenly on Earth, and is richest in the tropics. These tropical forest ecosystems cover less than 10 percent of earth's surface, and contain about 90 percent of the world's species. Marine biodiversity is usually highest along coasts in the Western Pacific, where sea surface temperature is highest, and in the mid-latitudinal band in all oceans. There are latitudinal gradients in species diversity. Biodiversity generally tends to cluster in hotspots, and has been increasing through time, but will be likely to slow in the future.

Related Research Articles

Bivalvia class of molluscs

Bivalvia, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. Bivalves as a group have no head and they lack some usual molluscan organs like the radula and the odontophore. They include the clams, oysters, cockles, mussels, scallops, and numerous other families that live in saltwater, as well as a number of families that live in freshwater. The majority are filter feeders. The gills have evolved into ctenidia, specialised organs for feeding and breathing. Most bivalves bury themselves in sediment where they are relatively safe from predation. Others lie on the sea floor or attach themselves to rocks or other hard surfaces. Some bivalves, such as the scallops and file shells, can swim. The shipworms bore into wood, clay, or stone and live inside these substances.

Scallop common name for several shellfish, many are a food

Scallop is a common name that is primarily applied to any one of numerous species of saltwater clams or marine bivalve mollusks in the taxonomic family Pectinidae, the scallops. However, the common name "scallop" is also sometimes applied to species in other closely related families within the superfamily Pectinoidea, which also includes the thorny oysters.

<i>Tonna galea</i> species of mollusc

Tonna galea, commonly known as the giant tun, is a species of marine gastropod mollusc in the family Tonnidae. This very large sea snail or tun snail is found in the North Atlantic Ocean as far as the coast of West Africa, in the Mediterranean Sea and the Caribbean Sea. The species was first described by Carl Linnaeus in 1758.

Limatula, the file shells or file clams, is a genus of marine bivalve molluscs in the family Limidae.

Cliona californiana, the yellow boring sponge, boring sponge or sulphur sponge, is a species of demosponge belonging to the family Clionaidae. It is native to the north-eastern Pacific Ocean and burrows into the shell valves of bivalve molluscs.

Marine invertebrates

Marine invertebrates are the invertebrates that live in marine habitats. Invertebrate is a blanket term that includes all animals apart from the vertebrate members of the chordate phylum. Invertebrates lack a vertebral column, and some have evolved a shell or a hard exoskeleton. As on land and in the air, marine invertebrates have a large variety of body plans, and have been categorised into over 30 phyla. They make up most of the macroscopic life in the oceans.

<i>Atrina rigida</i> species of mollusc

Atrina rigida, commonly called the rigid pen shell, is a species of bivalve mollusc in the family Pinnidae.

Polystira picta is a species of sea snail, a marine gastropod mollusk in the family Turridae, the turrids. It has been found in the shallow subtidal waters of the Gulf of Tehuantepec.

<i>Ensis ensis</i> species of mollusc

Ensis ensis, or the sword razor, is a razor clam, a marine bivalve mollusc in the family Pharidae. It lives buried in the sand and is found off the coasts of northwest Europe.

<i>Adamussium</i> genus of molluscs

Adamussium is a monotypic genus of bivalve molluscs in the large family of scallops, the Pectinidae. The Antarctic scallop is the only species in the genus though its exact relationship to other members of the family is unclear. It is found in the ice-cold seas surrounding Antarctica, sometimes at great depths.

<i>Crassadoma</i> species of mollusc

Crassadoma is a genus of rock scallops, marine bivalve molluscs in the family Pectinidae. It is monotypic, the only species being Crassadoma gigantea, the rock scallop, giant rock scallop or purple-hinge rock scallop. Although the small juveniles are free-swimming, they soon become sessile, and are cemented to the substrate. These scallops occur in the eastern Pacific Ocean.

Enigmonia is a genus of saltwater clams, a marine bivalve mollusc in the family Anomiidae, the jingle shells. Enigmonia aenigmatica, the mangrove jingle shell clam, is the only species in this monotypic genus. It is found living on mangroves in the Indo-Pacific Ocean.

<i>Dosinia dunkeri</i> species of mollusc

Dosinia dunkeri is a species of saltwater clam, a marine bivalve mollusc in the family Veneridae.

<i>Caryophyllia smithii</i> species of cnidarian

Caryophyllia smithii, the Devonshire cup coral, is a species of solitary coral in the family Caryophylliidae. It is native to the northeastern Atlantic Ocean, the North Sea and the Mediterranean Sea. There are shallow and deep-water forms which are structurally different. It forms part of a biodiverse community of rock encrusting organisms and is often parasitised by a barnacle.

Diplasterias brucei is a species of starfish in the family Asteriidae. It is found in the Pacific Ocean and Southern Ocean. It is a predator and scavenger and is unusual among starfish in that it broods its young.

Urticinopsis antarctica is a species of sea anemone in the family Actiniidae. It is found in the Southern Ocean around Antarctica.

Terrestrial mollusc

Terrestrial molluscs or land molluscs (mollusks) are ecological group that includes all molluscs that lives on land in contrast to freshwater and marine molluscs.

Lithophaga simplex is a species of bivalve mollusc in the family Mytilidae. It is a boring species, tunnelling into living coral colonies. It can be found in the tropical western central Pacific Ocean.

Idas simpsoni, previously known as Adipicola simpsoni, is a species of saltwater clam, a marine bivalve mollusc in the family Mytilidae, the mussels. It is a deepwater species and is only found attached to the bones of dead whales.

<i>Anasterias antarctica</i> species of echinoderm

Anasterias antarctica, commonly called the Cinderella starfish, is a species of starfish in the family Asteriidae. It is found in coastal waters in the Southern Ocean and around Antarctica.

References

  1. ↑ Bouchet, Philippe (2013). "Limatula hodgsoni (E. A. Smith, 1907)". World Register of Marine Species . Retrieved 16 February 2017.
  2. 1 2 "Limatula (Antarctolima) hodgsoni (Smith, 1907)". Antarctic Invertebrates. Smithsonian Institution. Retrieved 16 February 2017.
  3. ↑ Advances in Marine Biology. Academic Press. 1972. p. 149. ISBN   978-0-08-057933-7.
  4. ↑ Knox, George A. (2006). Biology of the Southern Ocean, Second Edition. CRC Press. p. 291. ISBN   978-1-4200-0513-4.
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