Triops cancriformis
Encyclopedia
Triops cancriformis, or tadpole shrimp (not to be confused with horseshoe crab
s), is a species of tadpole shrimp
found in Europe
, the Middle East
and Japan
.
Due to habitat destruction, many populations have recently been lost across its European range, so, the species is considered endangered in the United Kingdom
and in several European countries. In captivity they commonly grow up to 6 centimetres (2.4 in); however, in the wild they can achieve sizes of 11 cm (4.3 in).
In the UK, there are just two known populations: in a pool and adjacent area in the Caerlaverock Wetlands
in Scotland
, and a temporary pond in the New Forest
. The species is legally protected under Schedule 5 of the Wildlife and Countryside Act 1981
(as amended).
This species is considered to be one of the oldest living species on the planet at around 200 million years old. Fossils of this species from the Upper Triassic (Norian
) period appear virtually unchanged compared to modern day members of the species.
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.
In 1909, Ludwig Keilhack used the correct name "Triops cancriformis (Bosc)" in a field identification
key
of the freshwater fauna of Germany
. He took up the genus
name proposed by Schrank
and suggested that the genus name Apus be replaced with Triops
Schrank. 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 synonomy to support it. This was in a taxonomic review of the Notostraca
that also supported using the genus name Triops instead of Apus. In 1958, the International Commission on Zoological Nomenclature
(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.
Horseshoe crab
The Atlantic horseshoe crab, Limulus polyphemus, is a marine chelicerate arthropod. Despite its name, it is more closely related to spiders, ticks, and scorpions than to crabs. Horseshoe crabs are most commonly found in the Gulf of Mexico and along the northern Atlantic coast of North America...
s), is a species of tadpole shrimp
Notostraca
The order Notostraca comprises the single family Triopsidae, containing the tadpole shrimp or shield shrimp. The two genera, Triops and Lepidurus, are considered living fossils, having not changed significantly in outward form since the Triassic. They have a broad, flat carapace, which conceals the...
found in Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, the Middle East
Middle East
The Middle East is a region that encompasses Western Asia and Northern Africa. It is often used as a synonym for Near East, in opposition to Far East...
and Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
.
Due to habitat destruction, many populations have recently been lost across its European range, so, the species is considered endangered in the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
and in several European countries. In captivity they commonly grow up to 6 centimetres (2.4 in); however, in the wild they can achieve sizes of 11 cm (4.3 in).
In the UK, there are just two known populations: in a pool and adjacent area in the Caerlaverock Wetlands
WWT Caerlaverock
WWT Caerlaverock is wetland nature reserve in southwest Scotland, one of nine reserves in Britain operated by the Wildfowl and Wetlands Trust founded by Sir Peter Scott....
in Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
, and a temporary pond in the New Forest
New Forest
The New Forest is an area of southern England which includes the largest remaining tracts of unenclosed pasture land, heathland and forest in the heavily-populated south east of England. It covers south-west Hampshire and extends into south-east Wiltshire....
. The species is legally protected under Schedule 5 of the Wildlife and Countryside Act 1981
Wildlife and Countryside Act 1981
The Wildlife and Countryside Act 1981 is an Act of Parliament in the United Kingdom and was implemented to comply with the Directive 2009/147/EC on the conservation of wild birds...
(as amended).
This species is considered to be one of the oldest living species on the planet at around 200 million years old. Fossils of this species from the Upper Triassic (Norian
Norian
The Norian is a division of the Triassic geological period. It has the rank of an age or stage . The Norian lasted from 216.5 ± 2.0 to 203.6 ± 1.5 million years ago. It was preceded by the Carnian and succeeded by the Rhaetian.-Stratigraphic definitions:The Norian was named after the Noric Alps in...
) period appear virtually unchanged compared to modern day members of the species.
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. The presence of testicular lobes scattered amongst their ovaries confirmed they were in fact hermaphroditic. Fertilized females of 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 BoscLouis Augustin Guillaume Bosc
Louis Augustin Guillaume Bosc was a French botanist, invertebrate zoologist, and entomologist.-Biography:...
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.
In 1909, Ludwig Keilhack used the correct name "Triops cancriformis (Bosc)" in a field identification
Field guide
A field guide is a book designed to help the reader identify wildlife or other objects of natural occurrence . It is generally designed to be brought into the 'field' or local area where such objects exist to help distinguish between similar objects...
key
Single-access key
A 'key' in Biology is a modeling method used for categorizing species using logical choices. A single-access key is a key where the sequence and structure of identification steps is fixed by the author of the key...
of the freshwater fauna of Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
. He took up the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
name proposed by Schrank
Franz Paula von Schrank
Franz von Paula Schrank was a German botanist and entomologist.Schrank was the first director of the botanical gardens in Munich from 1809 to 1832.Shrank was the first author to use the genus name Triops...
and suggested that the genus name Apus be replaced with Triops
Triops
Triops is a genus of small crustaceans in the order Notostraca . They are considered living fossils, with a fossil record that reaches back to the Carboniferous, .-Relatives and fossil record:...
Schrank. 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 synonomy to support it. This was in a taxonomic review of the Notostraca
Notostraca
The order Notostraca comprises the single family Triopsidae, containing the tadpole shrimp or shield shrimp. The two genera, Triops and Lepidurus, are considered living fossils, having not changed significantly in outward form since the Triassic. They have a broad, flat carapace, which conceals the...
that also supported using the genus name Triops instead of Apus. In 1958, the International Commission on Zoological Nomenclature
International Commission on Zoological Nomenclature
The International Commission on Zoological Nomenclature is an organization dedicated to "achieving stability and sense in the scientific naming of animals". Founded in 1895, it currently comprises 28 members from 20 countries, mainly practicing zoological taxonomists...
(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.