Triops

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Triops
Triops longicaudatus2.jpg
Triops longicaudatus
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Branchiopoda
Order: Notostraca
Family: Triopsidae
Genus: Triops
Schrank, 1803
Species

Triops is a genus of small crustaceans in the order Notostraca (tadpole shrimp). The long-lasting resting eggs of several species of Triops are commonly sold in kits as pets. 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 to 10. In nature, they often inhabit temporary pools. [1]

Contents

Relatives and fossil record

The genus Triops can be distinguished from the only other living genus of Notostraca, Lepidurus , by the form of the telson (the end of its 'tail'), which bears only a pair of long, thin caudal extensions in Triops, while Lepidurus also bears a central platelike process. Only 24 hours after hatching they already resemble miniature versions of the adult form. [1]

Triops are sometimes called "living fossils", since fossils that have been attributed to this genus have been found in rocks hundreds of millions of years old. [2] However, careful analysis of these fossils cannot definitively assign these specimens to Triops. [3] Molecular clock estimates suggest that Triops split from Lepidurus during the Triassic or Jurassic, between 152.3–233.5 million years ago. The earliest diverging lineages of living Triops are found in areas that are part of the former supercontinent Gondwana, suggesting Triops originated in Gondwana. [4]

Triops can be found in Africa, Australia, Asia, South America, Europe (including Great Britain [5] ), and in some parts of North America where the climate is right. Some eggs stay unhatched from the previous group and hatch when rain soaks the area. Triops are often found in vernal pools.

Life cycle

Most species reproduce sexually, but some populations are dominated by hermaphrodites which produce internally fertilised eggs. Reproduction in T. cancriformis varies with latitude, with sexual reproduction dominating in the south of its range, and parthenogenesis dominating in the north. [6]

Triops eggs enter a state of extended diapause when dry, and will tolerate temperatures of up to 98 °C (208 °F) for 16 hours, whereas the adult cannot survive temperatures above 34 °C (93 °F) for 24 hours or 40 °C (104 °F) for 2 hours. [7] The diapause also prevents the eggs from hatching too soon after rain; the pool must fill with enough water for the dormancy to be broken. [7]

Taxonomy

Closeup of adult Triops showing naupliar ocellus Triops closeup.jpg
Closeup of adult Triops showing naupliar ocellus

The name Triops comes from the Greek τρία (tría) meaning "three" and ὤψ (ops) meaning "eye". [8] The head of T. longicaudatus bears a pair of dorsal compound eyes that lie close to each other and are nearly fused together. The compound eyes are generally sessile (not stalked). In addition, there is a naupliar ocellus (the "third eye") between them. The compound eyes are on the surface of the head, but the ocellus is deep within the head. All the eyes, however, are easily visible through the shell covering of the head.

Upper and underside Triops. 1 eyes, 2 antennae, 3 tail, 4 torso, 5 antenne, 6 1st torso appendix, 7 legs with gill, 8 middelline, 9 tail, 10 anus Kian-triops.jpg
Upper and underside Triops. 1 eyes, 2 antennae, 3 tail, 4 torso, 5 antenne, 6 1st torso appendix, 7 legs with gill, 8 middelline, 9 tail, 10 anus

Franz von Paula Schrank was the first author to use the genus name Triops, [9] coining it in his 1803 work on the fauna of Bavaria. Their German name was Dreyauge, which means 'three-eye'. He collected and described specimens from the same locality in Regensburg from which Schäffer, another naturalist who had studied the Notostraca, obtained his specimens in the 1750s. However, other authors, starting with Louis Augustin Guillaume Bosc, had adopted the genus name Apus for the organisms Schrank had named Triops

Ludwig Keilhack used the genus name Triops in his 1909 field identification key of the freshwater fauna of Germany. He suggested that the genus name Apus be replaced by Triops Schrank since an avian genus had already been described by Giovanni Antonio Scopoli under the name Apus . [9] However, Robert Gurney preferred the name Apus Schäffer. He suggested that the name '…Triops Schrank, may be returned to the obscurity from which it was unearthed'. [9] This controversy continued and was not resolved until the 1950s.

In his 1955 taxonomic review of the Notostraca, Alan R. Longhurst supported Keilhack's genus name Triops over Apus. Longhurst provided historical evidence to support this position. [9] The International Commission on Zoological Nomenclature (ICZN) followed Longhurst in their 1958 ruling on the usage and origin of the genus names Triops and Apus. They rejected the genus name Apus and instead recognized the genus name Triops Schrank, 1803 (ICZN name no. 1246). [9]

Although the taxonomy of the genus has not been reviewed since 1955, the following species are recognised: [10] [11]

T. mauritanicus was considered a subspecies of T. cancriformis by Longhurst in 1955, but was given full species status again by Korn et al. in 2006. [12]

Note that for several of these species there are different varieties, some of which have recently been suggested as subspecies and even separate species. T. longicaudatus, for example, may actually be several species lumped together, and T. cancriformis is generally recognized as having three subspecies: T. cancriformis cancriformis, T. c. mauretanicus, and T. c. simplex. [13] Also, the albino form has the special name of T. cancriformis var. Beni-Kabuto Ebi.

Relationship with humans

T. longicaudatus is considered a human ally against the West Nile virus, as the individuals consume Culex mosquito larvae. [14] They also are used as a biological pest control in Japan, eating weeds in rice paddies. The Beni-Kabuto Ebi Albino variant of T. cancriformis is particularly valued for this purpose. In Wyoming, the presence of T. longicaudatus usually indicates a good chance of the hatching of American spadefoot toads.

Dried eggs of T. longicaudatus are sold in kits to be raised as aquarium pets, sold under the name of "aquasaurs", "trigons" or "triops". Among enthusiasts, T. cancriformis is also common. Other species often encountered in captivity include T. australiensis , T. newberryi and T. granarius .

Captive Triops are frequently kept in aquaria and fed a diet consisting mainly of carrots, shrimp pellets and dried shrimp. [15] Often they are also given living shrimp and Daphnia as live prey. [16] Because they can feed on just about anything they are also fed lunch meat, crackers, potatoes etc. [17]

In California, T. longicaudatus has emerged as a significant pest of rice cultivation, due to its digging behaviour uprooting young rice seedlings. [18]

See also

Related Research Articles

<span class="mw-page-title-main">Branchiopoda</span> Class of crustaceans

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

<span class="mw-page-title-main">Notostraca</span> 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 end of the Devonian, around 360 million years ago. 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.

<span class="mw-page-title-main">Clam shrimp</span> 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, due to the fact that water fleas are nested within clam shrimps. Clam shrimp are now divided into three orders, Cyclestherida, Laevicaudata, and Spinicaudata, in addition to the fossil family Leaiidae.

<span class="mw-page-title-main">Anostraca</span> Order of crustaceans

Anostraca is one of the four orders of crustaceans in the class Branchiopoda; its members are referred to as fairy shrimp. They live in vernal pools and hypersaline lakes across the world, and they have even been found in deserts, ice-covered mountain lakes, and Antarctic ice. They are usually 6–25 mm (0.24–0.98 in) long. Most species have 20 body segments, bearing 11 pairs of leaf-like phyllopodia, and the body lacks a carapace. They swim "upside-down" and feed by filtering organic particles from the water or by scraping algae from surfaces, with the exception of Branchinecta gigas, or "giant fairy shrimp", which is itself a predator of other species of anostracans. They are an important food for many birds and fish, and some are cultured and harvested for use as fish food. There are 300 species spread across 8 families.

<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.

<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 Greek ὤψ or ṓps, meaning "eye" prefixed with Latin tri-, "three", in reference to its three eyes. Longicaudatus is an Latin neologism combining longus ("long") and caudatus ("tailed"), referring to its long tail structures. Triops longicaudatus is found in fresh water 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.

<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.

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

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

<span class="mw-page-title-main">Crustacean larva</span> 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>Chenops</i> Genus of small freshwater animals

Chenops is an extinct genus of notostracan which existed in the Yixian Formation, Inner Mongolia, and the Jehol fauna of China during the early Cretaceous period. The genus was erected by Thomas A. Hegna and Ren Dong in 2010 to describe the Yixian species, Chenops yixianensis. A second species, originally described as "Prolepidurus oblongus", from the Jehol fauna, was redescribed as C. oblongus.

<i>Jeholops</i> Genus of small freshwater animals

Jeholops is an extinct genus of notostracan which existed in the Yixian Formation, inner Mongolia, China during the early Cretaceous period. It was described by Thomas A. Hegna and Ren Dong in 2010, and the only species is Jeholops hongi.

<span class="mw-page-title-main">Sakura shrimp</span> Species of crustacean

Lucensosergia lucens is a species of shrimp popularly known as the sakura shrimp or sakura ebi. The translucent pink shrimp derives its name from sakura, the Japanese word for the cherry blossom. The species grows to about 4–5 cm and lives primarily in Suruga Bay in Shizuoka Prefecture, Japan, where it is caught to be eaten. It is also caught in Taiwan.

<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.

Triops mauritanicus is a species of tadpole shrimp, found in Southern Spain and Morocco. This species of Triops can grow to 4 to 6 cm and can be expected to live for 90-120 days on average. This species can be usually found in arid areas and are sometimes sold in kits.

Triop gadensis is a species of arthropod in the genus Triops, that belongs to the family of Triopsidae. Triop gadensis are omnivores and in the wild they mainly eat algae and protozoa; larger triop gadensis that are about 1-2 cm in length feed on detritus, plant fibres and tiny crustaceans such as ostracods or copepods. However when food sources are scarce they will cannibalize each other. These crustaceans swim by drag swim power, which is a method of swimming that all triops use.

References

  1. 1 2 Denton Belk (2007). "Branchiopoda". In Sol Felty Light; James T. Carlton (eds.). The Light and Smith manual: intertidal invertebrates from central California to Oregon (4th ed.). University of California Press. pp. 414–417. ISBN   978-0-520-23939-5.
  2. ↑ Chip Hannum & Stuart Halliday. "An Introduction to Triops". MyTriops.com. Archived from the original on August 5, 2010. Retrieved October 4, 2010.
  3. ↑ 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.
  4. ↑ 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.
  5. ↑ Autumnwatch. 5 November 2015. BBC Two.
  6. ↑ Graham Bell (1982). The masterpiece of nature: the evolution and genetics of sexuality. Croom Helm applied biology series. Cambridge University Press. p. 243. ISBN   978-0-85664-753-6.
  7. 1 2 Patrick L. Osborne (2000). "Hot deserts and environmental factors". Tropical ecosystems and ecological concepts. Cambridge University Press. pp. 18–49. ISBN   978-0-521-64523-2.
  8. ↑ John Scarborough (1992). "Crustacea". Medical and biological terminologies: classical origins. Volume 13 of Oklahoma Series in Classical Culture. University of Oklahoma Press. pp. 75–81. ISBN   978-0-8061-3029-3.
  9. 1 2 3 4 5 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.
  10. ↑ Chip Hannum. "A Brief Overview of the Species". MyTriops.com. Retrieved October 4, 2010.
  11. ↑ Michael Korn; Andy J. Green; Margarida Machado; Juan García-de-Lomas; Margarida Cristo; Luís Cancela da Fonseca; Dagmar Frisch; José L. Pérez-Bote & Anna K. Hundsdoerfer (2010). "Phylogeny, molecular ecology and taxonomy of southern Iberian lineages of Triops mauritanicus (Crustacea: Notostraca)" (PDF). Organisms Diversity and Evolution. 10 (5): 409–440. doi:10.1007/s13127-010-0026-y. hdl: 10261/38752 . S2CID   14145762. Archived from the original (PDF) on 2011-09-08.
  12. ↑ Michael Korn; Federico Marrone; Jose L. Pérez-Bote; Margarida Machado; Margarida Cristo; Luís Cancela de Fonseca & Anna K. Hundsdoerfer (2006). "Sister species within the Triops cancriformis lineage (Crustacea, Notostraca)" (PDF). Zoologica Scripta . 35 (4): 301–322. doi:10.1111/j.1463-6409.2006.00230.x. S2CID   84611515. Archived from the original (PDF) on 2017-08-12. Retrieved 2011-12-14.
  13. ↑ Species list Archived 2011-10-06 at the Wayback Machine . Mytriops.com. Retrieved on 2016-07-23.
  14. ↑ Tietze, N. S., & Mulla, M. S. (1989). Prey-size selection by Triops longicaudatus (Notostraca: Triopsidae) feeding on immature stages of Culex quinquefasciatus. Journal of the American Mosquito Control Association. Retrieved on 2023-03-03.
  15. ↑ Frequently Asked Questions. triops.com
  16. ↑ Triops food Archived 2007-05-29 at the Wayback Machine . Mytriops.com (2003-10-28). Retrieved on 2016-07-23.
  17. ↑ "Triops and their food". Triops-eggs.com. Retrieved on 2016-07-23.
  18. ↑ Bloese, Joanna B; Goding, Kevin M; Godfrey, Larry D (2020-06-06). Musser, Fred (ed.). "Effect of Rice Winter Cultural Management Practices on the Size of the Hatching Population of Triops longicaudatus (Notostraca: Triopsidae) in California Rice Fields". Journal of Economic Entomology. 113 (3): 1243–1247. doi:10.1093/jee/toaa006. ISSN   0022-0493. PMID   31971596.
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