Thymops birsteini
Encyclopedia
Thymops birsteini, the Patagonian lobsterette, is a species
of lobster
found around the coasts of South America
, particularly the South Atlantic. It belongs to the monotypic
genus Thymops.
around South America, particularly in the Argentine Sea
. In the Atlantic Ocean
, it is found south of 37° south
, with Uruguay
representing the northern extremity of its distribution; on the Chile
an (Pacific
) side, it is found south of 51° south
. Its range
includes the areas around the Falkland Islands
(Islas Malvinas) and areas near South Georgia, extending as far south as 57°
, close to the Antarctic Peninsula
. It lives at depths of 120–1500 m (393.7–4,921.3 ).
s, four other pairs of pereiopods, and a long pleon
(tail). The carapace
is granular, especially in the front half, and it bears a rostrum
which divides into two points at its tip. The total length may range from 8 to 25 cm (3.1 to 9.8 ), with the carapace being 2 centimetre long. Smaller individuals are found in shallower waters, and larger individuals are found at greater depths (up to 1400 m or 4,593.2 ft). There is also latitudinal
variation in colour, with northern individuals being pale yellow, while those from further south are maroon.
Dissostichus eleginoides. It seems to prefer mud
dy bottoms, and has been observed entering and exiting burrow
s.
, T. birsteini broods its eggs
on the female's pleopods. One female may carry up to 380 eggs, each 1.5–1.9 mm (0.0590551181102362–0.0748031496062992 ) in diameter. The eggs grow as they develop to a size of 2.9 millimetre. Newly-hatched larva
e have a carapace length of 1.7 millimetre, and are present in smaller numbers than the eggs, with a maximum of 43 observed on a single female. This extended larval release has previously been found in other sub-Antarctic decapods
, and is an adaptation
to the low temperature
, the long time taken for brooding, and the low overall fecundity
.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of lobster
Lobster
Clawed lobsters comprise a family of large marine crustaceans. Highly prized as seafood, lobsters are economically important, and are often one of the most profitable commodities in coastal areas they populate.Though several groups of crustaceans are known as lobsters, the clawed lobsters are most...
found around the coasts of South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, particularly the South Atlantic. It belongs to the monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
genus Thymops.
Distribution
T. birsteini is found on the continental shelfContinental shelf
The continental shelf is the extended perimeter of each continent and associated coastal plain. Much of the shelf was exposed during glacial periods, but is now submerged under relatively shallow seas and gulfs, and was similarly submerged during other interglacial periods. The continental margin,...
around South America, particularly in the Argentine Sea
Argentine Sea
thumb|150px|Argentine Sea, off the [[Atlantic Ocean|atlantic]] coast of ArgentinaThe Argentine Sea refers to the sea within the continental shelf off the Argentine mainland...
. In the Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
, it is found south of 37° south
37th parallel south
The 37th parallel south is a circle of latitude that is 37 degrees south of the Earth's equatorial plane. It crosses the Atlantic Ocean, the Indian Ocean, Australasia, the Pacific Ocean and South America....
, with Uruguay
Uruguay
Uruguay ,officially the Oriental Republic of Uruguay,sometimes the Eastern Republic of Uruguay; ) is a country in the southeastern part of South America. It is home to some 3.5 million people, of whom 1.8 million live in the capital Montevideo and its metropolitan area...
representing the northern extremity of its distribution; on the Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
an (Pacific
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
) side, it is found south of 51° south
51st parallel south
The 51st parallel south is a circle of latitude that is 51 degrees south of the Earth's equatorial plane. It crosses the Atlantic Ocean, the Indian Ocean, the Pacific Ocean and South America....
. Its range
Range (biology)
In biology, the range or distribution of a species is the geographical area within which that species can be found. Within that range, dispersion is variation in local density.The term is often qualified:...
includes the areas around the Falkland Islands
Falkland Islands
The Falkland Islands are an archipelago in the South Atlantic Ocean, located about from the coast of mainland South America. The archipelago consists of East Falkland, West Falkland and 776 lesser islands. The capital, Stanley, is on East Falkland...
(Islas Malvinas) and areas near South Georgia, extending as far south as 57°
57th parallel south
The 57th parallel south is a circle of latitude that is 57 degrees south of the Earth's equatorial plane. No land lies on the parallel—it crosses nothing but ocean.Starting at the Prime Meridian and heading eastwards, the parallel 57° south passes through:...
, close to the Antarctic Peninsula
Antarctic Peninsula
The Antarctic Peninsula is the northernmost part of the mainland of Antarctica. It extends from a line between Cape Adams and a point on the mainland south of Eklund Islands....
. It lives at depths of 120–1500 m (393.7–4,921.3 ).
Description
T. birsteini resembles a typical lobster, with two large clawClaw
A claw is a curved, pointed appendage, found at the end of a toe or finger in most mammals, birds, and some reptiles. However, the word "claw" is also often used in reference to an invertebrate. Somewhat similar fine hooked structures are found in arthropods such as beetles and spiders, at the end...
s, four other pairs of pereiopods, and a long pleon
Pleon
Pleon is a Europe based Public Relations and communications consultancy. It is part of the Brodeur Pleon Worldwide network and a subsidiary of BBDO Worldwide. Pleon belongs to the Omnicom Group. Pleon is headquartered in Düsseldorf, Germany.- Overview :...
(tail). The carapace
Carapace
A carapace is a dorsal section of the exoskeleton or shell in a number of animal groups, including arthropods such as crustaceans and arachnids, as well as vertebrates such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron.-Crustaceans:In crustaceans, the...
is granular, especially in the front half, and it bears a rostrum
Rostrum (anatomy)
The term rostrum is used for a number of unrelated structures in different groups of animals:*In crustaceans, the rostrum is the forward extension of the carapace in front of the eyes....
which divides into two points at its tip. The total length may range from 8 to 25 cm (3.1 to 9.8 ), with the carapace being 2 centimetre long. Smaller individuals are found in shallower waters, and larger individuals are found at greater depths (up to 1400 m or 4,593.2 ft). There is also latitudinal
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
variation in colour, with northern individuals being pale yellow, while those from further south are maroon.
Ecology
Little is known about the biological interactions of T. birsteini. It is occasionally eaten by the Patagonian toothfishPatagonian toothfish
The Patagonian toothfish, Dissostichus eleginoides , is a fish found in the cold, temperate waters of the southern Atlantic, southern Pacific, Indian, and Southern Oceans on seamounts and continental shelves around most sub-Antarctic islands.A close relative, the Antarctic toothfish , is found...
Dissostichus eleginoides. It seems to prefer mud
Mud
Mud is a mixture of water and some combination of soil, silt, and clay. Ancient mud deposits harden over geological time to form sedimentary rock such as shale or mudstone . When geological deposits of mud are formed in estuaries the resultant layers are termed bay muds...
dy bottoms, and has been observed entering and exiting burrow
Burrow
A burrow is a hole or tunnel dug into the ground by an animal to create a space suitable for habitation, temporary refuge, or as a byproduct of locomotion. Burrows provide a form of shelter against predation and exposure to the elements, so the burrowing way of life is quite popular among the...
s.
Life cycle
As in other pleocyematesPleocyemata
Pleocyemata is a sub-order of decapod crustaceans, erected by Martin Burkenroad in 1963. Burkenroad's classification replaced the earlier sub-orders of Natantia and Reptantia with the monophyletic groups Dendrobranchiata and Pleocyemata...
, T. birsteini broods its eggs
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
on the female's pleopods. One female may carry up to 380 eggs, each 1.5–1.9 mm (0.0590551181102362–0.0748031496062992 ) in diameter. The eggs grow as they develop to a size of 2.9 millimetre. Newly-hatched larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e have a carapace length of 1.7 millimetre, and are present in smaller numbers than the eggs, with a maximum of 43 observed on a single female. This extended larval release has previously been found in other sub-Antarctic decapods
Decapoda
The decapods or Decapoda are an order of crustaceans within the class Malacostraca, including many familiar groups, such as crayfish, crabs, lobsters, prawns and shrimp. Most decapods are scavengers. It is estimated that the order contains nearly 15,000 species in around 2,700 genera, with...
, and is an adaptation
Adaptation
An adaptation in biology is a trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation....
to the low temperature
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
, the long time taken for brooding, and the low overall fecundity
Fecundity
Fecundity, derived from the word fecund, generally refers to the ability to reproduce. In demography, fecundity is the potential reproductive capacity of an individual or population. In biology, the definition is more equivalent to fertility, or the actual reproductive rate of an organism or...
.