Triops cancriformis

Last updated

Triops cancriformis
Triops cancriformis2.jpg
Triops cancriformis Nauplien
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Branchiopoda
Order: Notostraca
Family: Triopsidae
Genus: Triops
T. cancriformis
Binomial name
Triops cancriformis
(Bosc, 1801)  [1]
The range of Triops cancriformis

Triops cancriformis, European tadpole shrimp or tadpole shrimp, is a species of tadpole shrimp found in Europe to the Middle East and India. [2]


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. [2] In captivity they commonly grow up to 6 centimetres (2.4 in); in the wild they can achieve sizes of 11 cm (4.3 in). [2]

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. [3] The species is legally protected under Schedule 5 of the Wildlife and Countryside Act 1981 (as amended).

Fossils from the Upper Triassic (Norian) of Germany, around 237 million years old have been attributed to this species as the subspecies T. cancriformis minor, due to their great similarity to modern day members of the species. [4] However, later research showed that their ontogenetic growth was quite different from the living species, and they were better considered a distinct species, "Notostraca" minor, with an uncertain position within Notostraca. [5] Genetic evidence also indicates that T. cancriformis only diverged from other Triops species around 23.7–49.6 million years ago. [6]

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 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 made the first officially recognised species description of Triops cancriformis. [7] 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. [7] The genus name Apus was pre-occupied by a genus of birds (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 Germany. He took up the genus 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. [8]

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. [9] 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. [7]

Human uses

Triops cancriformis Beni-Kabuto Ebi Albino feeding on a piece of rehydrated dried shrimp, ultra closeup showing how transparent the carapace is. Beni-KabutoEbiAlbino1.jpg
Triops cancriformis Beni-Kabuto Ebi Albino feeding on a piece of rehydrated dried shrimp, ultra closeup showing how transparent the carapace is.

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

Related Research Articles

Branchiopoda Class of crustaceans

Branchiopoda is a class of crustaceans. It comprises fairy shrimp, clam shrimp, Diplostraca, Notostraca and the Devonian Lepidocaris. They are mostly small, freshwater animals that feed on plankton and detritus.

Binomial nomenclature System of identifying species of organisms using a two-part name

In taxonomy, binomial nomenclature, also called binominal nomenclature or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages. Such a name is called a binomial name, a binomen, binominal name or a scientific name; more informally it is also called a Latin name.

International Code of Zoological Nomenclature Code of scientific nomenclature for animals

The International Code of Zoological Nomenclature (ICZN) is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals. It is also informally known as the ICZN Code, for its publisher, the International Commission on Zoological Nomenclature. The rules principally regulate:

Living fossil Organism resembling a form long shown in the fossil record

A living fossil is an extant taxon that cosmetically resembles related species known only from the fossil record. To be considered a living fossil, the fossil species must be old relative to the time of origin of the extant clade. Living fossils commonly are of species-poor lineages, but they need not be. While the body plan of a living fossil remains superficially similar, it is never the same species as the remote relatives it resembles, because genetic drift would inevitably change its chromosomal structure.

Holotype Example of an organism used to describe its species

A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several examples, but explicitly designated as the holotype. Under the International Code of Zoological Nomenclature (ICZN), a holotype is one of several kinds of name-bearing types. In the International Code of Nomenclature for algae, fungi, and plants (ICN) and ICZN, the definitions of types are similar in intent but not identical in terminology or underlying concept.

Notostraca Order of small freshwater animals

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 the Devonian. They have a broad, flat carapace, which conceals the head and bears a single pair of compound eyes. The abdomen is long, appears to be segmented and bears numerous pairs of flattened legs. The telson is flanked by a pair of long, thin caudal rami. Phenotypic plasticity within taxa makes species-level identification difficult, and is further compounded by variation in the mode of reproduction. Notostracans are omnivores living on the bottom of temporary pools and shallow lakes.

Clam shrimp Suborder of arthropods

Clam shrimp are a group of bivalved branchiopod crustaceans that resemble the unrelated bivalved molluscs. They are extant and also known from the fossil record, from at least the Devonian period and perhaps before. They were originally classified in the former order Conchostraca, which later proved to be paraphyletic and was subsumed into the superorder Diplostraca. Clam shrimp now make up three of the seven orders in Diplostraca, Cyclestherida, Laevicaudata, and Spinicaudata, in addition to the fossil family Leaiidae.

<i>Triops</i> Genus of small crustaceans

Triops is a genus of small crustaceans in the order Notostraca. The long-lasting resting eggs of several species of Triops are commonly sold in kits as a pet. The animals hatch upon contact with fresh water. Most adult-stage Triops have a life expectancy of up to 90 days and can tolerate a pH range of 6–10. In nature, they often inhabit temporary pools.

<i>Apus</i> (bird) Genus of birds

The bird genus Apus comprise some of the Old World members of the family Apodidae, commonly known as swifts.

Nomenclature codes or codes of nomenclature are the various rulebooks that govern biological taxonomic nomenclature, each in their own broad field of organisms. To an end-user who only deals with names of species, with some awareness that species are assignable to families, it may not be noticeable that there is more than one code, but beyond this basic level these are rather different in the way they work.

<i>Triops longicaudatus</i> Species of small freshwater animal

Triops longicaudatus is a freshwater crustacean of the order Notostraca, resembling a miniature horseshoe crab. It is characterized by an elongated, segmented body, a flattened shield-like brownish carapace covering two thirds of the thorax, and two long filaments on the abdomen. The genus name Triops comes from Ancient Greek ὤψ or ṓps, meaning "eye" prefixed with Latin tri-, "three", in reference to its three eyes. Longicaudatus is a Latin neologism combining longus ("long") and caudatus ("tailed"), referring to its long tail structures. Triops longicaudatus is found in freshwater ponds and pools, often in places where few higher forms of life can exist.

<i>Lepidurus</i> Genus of tadpole shrimp

Lepidurus is a genus of small crustaceans in the order Notostraca. It is the larger of the two extant genera of the tadpole shrimps, the other being Triops. They are commonly found in vernal pools and survive dry periods with the help of long lasting resting eggs.

Androdioecy is a reproductive system characterized by the coexistence of males and hermaphrodites. Androdioecy is rare in comparison with the other major reproductive systems: dioecy, gynodioecy and hermaphroditism. In animals, androdioecy has been considered a stepping stone in the transition from dioecy to hermaphroditism, and vice versa.

<i>Triops australiensis</i> Species of small freshwater animal

Triops australiensis, sometimes referred to as a shield shrimp, is an Australian species of the tadpole shrimp Triops.

<i>Triops newberryi</i> Species of small freshwater animal

Triops newberryi is a species of Triops found on the western coast of North America, commonly in valleys throughout the states of Washington, Oregon, California, and small areas of Nevada, Utah, New Mexico, and Mexico, with at least one disjunct population in Kansas. They are found in vast numbers though in the Coachella Valley in California. T. newberryi has been reported to have potential as a biocontrol agent for larval mosquitoes breeding in seasonally-flooded habitats. T. newberryi is genetically distinct from T. longicaudatus, the dominant species in the Central United States.

<i>Triops granarius</i> Species of small freshwater animal

Triops granarius is a species of tadpole shrimp with a broad distribution from Africa and the Middle East to China and Japan, although there are indications that it, as presently defined, is a species complex. They have elongated bodies and large flaps. Triops granarius can be kept as pets in home aquaria. Their life expectancy is up to 90 days, and in that time they can grow more than 6 cm in length.

Crustacean larva Crustacean larval and immature stages between hatching and adult form

Crustaceans may pass through a number of larval and immature stages between hatching from their eggs and reaching their adult form. Each of the stages is separated by a moult, in which the hard exoskeleton is shed to allow the animal to grow. The larvae of crustaceans often bear little resemblance to the adult, and there are still cases where it is not known what larvae will grow into what adults. This is especially true of crustaceans which live as benthic adults, more-so than where the larvae are planktonic, and thereby easily caught.

<i>Lepidurus apus</i> Species of small freshwater animal

Lepidurus apus, commonly known as a tadpole shrimp, is a notostracan in the family Triopsidae, one of a lineage of shrimp-like crustaceans that have had a similar form since the Triassic period and are considered living fossils. This species is cosmopolitan, inhabiting temporary freshwater ponds over much of the world, and the most widespread of the tadpole shrimps. Like other notostracans, L. apus has a broad carapace, long segmented abdomen, and large numbers of paddle-like legs. It reproduces by a mixture of sexual reproduction and self-fertilisation of females.


  1. "Triops cancriformis". Integrated Taxonomic Information System.
  2. 1 2 3 "Tadpole shrimp - Triops cancriformis". ARKive. Archived from the original on 2008-10-07. Retrieved April 20, 2009.
  3. "Triops, the 300 million year-old living fossil". Planet Earth online. 22 December 2008. Archived from the original on 2009-07-05. Retrieved 22 July 2009.
  4. Klaus-Peter Kelber - Triops
  5. Wagner, Philipp; Haug, Joachim T.; Sell, Jürgen; Haug, Carolin (December 2017). "Ontogenetic sequence comparison of extant and fossil tadpole shrimps: no support for the "living fossil" concept". PalZ. 91 (4): 463–472. doi:10.1007/s12542-017-0370-8. ISSN   0031-0220. S2CID   90922613.
  6. Korn, Michael; Rabet, Nicolas; Ghate, Hemant V.; Marrone, Federico; Hundsdoerfer, Anna K. (December 2013). "Molecular phylogeny of the Notostraca". Molecular Phylogenetics and Evolution. 69 (3): 1159–1171. doi:10.1016/j.ympev.2013.08.006. hdl: 10447/83883 . PMID   23973879.
  7. 1 2 3 Ole S. Møller, Jørgen Olesen & Jens T. Høeg (2003). "SEM studies on the early larval development of Triops cancriformis (Bosc) (Crustacea: Branchiopoda, Notostraca)" (PDF). Acta Zoologica . 84 (4): 267–284. doi:10.1046/j.1463-6395.2003.00146.x.
  8. Hemming, Francis, ed. (1958). "Opinion 502". Opinions and Declarations Rendered by the International Commission on Zoological Nomenclature. Vol. 18. London: International Trust for Zoological Nomenclature. pp. 65–120.
  9. Alan R. Longhurst (1955). "A review of the Notostraca". Bulletin of the British Museum (Natural History) . 3 (1): 1–57. doi:10.5962/bhl.part.4119.