''Triops cancriformis'', European tadpole shrimp or tadpole shrimp is a species of tadpole shrimp found in

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

to the

Middle East The Middle East (term originally coined in English language) is a geopolitical region encompassing the Arabian Peninsula, the Levant, Turkey, Egypt, Iran, and Iraq. The term came into widespread usage by the United Kingdom and western Eur ...

and

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

. Due to

habitat destruction Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...

, many populations have recently been lost across its European range, so, the species is considered

endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching, inv ...

in the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...

and in several European countries. In captivity they commonly grow up to ; in the wild they can achieve sizes of . In the UK, there are just two known populations: in a pool and adjacent area in the Caerlaverock Wetlands in

Scotland Scotland is a Countries of the United Kingdom, country that is part of the United Kingdom. It contains nearly one-third of the United Kingdom's land area, consisting of the northern part of the island of Great Britain and more than 790 adjac ...

, and a temporary pond in the

New Forest The New Forest is one of the largest remaining tracts of unenclosed pasture land, heathland and forest in Southern England, covering southwest Hampshire and southeast Wiltshire. It was proclaimed a royal forest by William the Conqueror, featu ...

. The species is legally protected under Schedule 5 of the Wildlife and Countryside Act 1981 (as amended). In the past, fossils from the

Lower Triassic The Early Triassic is the first of three epoch (geology), epochs of the Triassic Period (geology), Period of the geologic timescale. It spans the time between 251.9 annum, Ma and Ma (million years ago). Rocks from this epoch are collectively kno ...

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

and

Upper Triassic The Late Triassic is the third and final epoch of the Triassic Period in the geologic time scale, spanning the time between Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch and followed by the Early Jurassic Epoch. T ...

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

have been attributed to this species, with some even described as specimens of the subspecies ''T. c. minor'', but later research reassigned all of these Triassic specimens to different extinct taxa of uncertain taxonomic family: the

notostraca The order Notostraca, containing the single family Triopsidae, is a group of crustaceans known as tadpole shrimp or shield shrimp. The two genera, ''Triops'' and ''Lepidurus'', are considered living fossils, with similar forms having existed since ...

n ''Apudites antiquus'' and the diplostracans ''Olesenocaris galli'' and ''Grauvogelocaris alsatica''. The putative Lower Permian subspecies from France has also been redescribed as a separate

n taxon, ''Heidiops permiensis''. Genetic evidence indicates that ''T. cancriformis'' only diverged from other ''Triops'' species around 23.7–49.6 million years ago.

Life cycle

''Triops cancriformis'' has a very fast life cycle, and individuals become mature in about two weeks after hatching. Their populations can be gonochoric, hermaphroditic or androdioecious. The latter is a very rare reproductive mode in animals, in which populations are made of hermaphrodites, with a small proportion of males. Due to this lack of males, early researchers thought Triops were

parthenogenetic Parthenogenesis (; from the Greek + ) is a natural form of asexual reproduction in which the embryo develops directly from an egg without need for fertilization. In animals, parthenogenesis means the development of an embryo from an unfertiliz ...

. The presence of testicular lobes scattered amongst their ovaries confirmed they were in fact hermaphroditic. Fertilized females or hermaphrodites produce diapausing eggs or cysts, able to survive decades in the sediment of the ponds and lakes they inhabit. These eggs are resistant to drought and temperature extremes.

Taxonomic history

In 1801,

Louis Augustin Guillaume Bosc Louis Augustin Guillaume Bosc (or Louis-Augustin Bosc d'Antic) (29 January 1759 – 10 July 1828) was a French botanist, invertebrate zoologist, and entomologist. Biography Bosc was born in Paris, the son of Paul Bosc d’Antic, a medical doctor ...

made the first officially recognised species description of ''Triops cancriformis''. He named this species ''Apus cancriformis''. Other authors used the name ''Apus cancriformis'' over the years but often with the wrong original author of this name. The genus name '' Apus'' was pre-occupied by a genus of

birds Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

(described in 1777), rendering the name invalid for the tadpole shrimp. In 1909, Ludwig Keilhack used the correct name "''Triops cancriformis'' (Bosc)" in a field identification key of the freshwater fauna of

. He took up the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

name proposed by Schrank and suggested that the genus name ''Apus'' be replaced with '' Triops'' Schrank since '' Apus'' had been used since 1777 as the genus name of some birds (commonly known as swifts). However, other authors disagreed with him and the controversy continued until the 1950s. In 1955, Alan Longhurst provided the original author of ''T. cancriformis'' as "''Triops cancriformis'' (Bosc, 1801)" with a full history of synonymy to support it. This was in a taxonomic review of the

Notostraca The order Notostraca, containing the single family Triopsidae, is a group of crustaceans known as tadpole shrimp or shield shrimp. The two genera, ''Triops'' and ''Lepidurus'', are considered living fossils, with similar forms having existed since ...

that also supported using the genus name ''Triops'' instead of ''Apus''. In 1958, the

International Commission on Zoological Nomenclature The International Commission on Zoological Nomenclature (ICZN) is an organization dedicated to "achieving stability and sense in the scientific naming of animals". Founded in 1895, it currently comprises 26 commissioners from 20 countries. Orga ...

(ICZN) recognised the name ''Triops cancriformis'' (Bosc, 1801–1802) (ICZN name no. 1476) as officially the oldest. They also recognised the genus name ''Triops'' Schrank instead of ''Apus''. They followed Longhurst in these decisions.

Etymology

The genus name ''Triops'' comes from

Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...

τρία (''tría''), meaning "three", and ὄψ (''óps''), meaning "face" or "eye". The specific name ''cancriformis'' comes from

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

''cancer'', meaning "crab", and ''forma'', meaning "form".

Human uses

Although members of the genus ''Triops'' usually have no economic importance, the Beni-kabuto ebi albino variant of ''Triops cancriformis'' has been used to control mosquitoes and weeds in Asian rice fields. ''Triops cancriformis'' is the second most common species raised by hobbyists next to ''

Triops longicaudatus ''Triops longicaudatus'' (commonly called American tadpole shrimp or longtail tadpole shrimp) is a freshwater crustacean of the order Notostraca, resembling a miniature horseshoe crab. It is characterized by an elongated, segmented body, a flatt ...

''. They are particularly valued for their lower hatching temperature and somewhat longer lifespan as well as potentially larger size.

References

{{Taxonbar, from=Q132808 Taxa named by Louis Augustin Guillaume Bosc Crustaceans described in 1801 Notostraca Crustaceans of Asia Crustaceans of Europe