Overview

Brief Summary

Triop or tadpole shrimps (Triops)

Triops or tadpole shrimps Triops are small crustaceans in the order Notostraca. The name Triops comes from the Greek for "three eyes" [6] and was first used by Franz von Paula Schrank [7] in his 1803 work on the fauna of Bavaria; the German name, Dreyauge, means 'three-eye' in English. He collected and described specimens from the same locality in Regensburg from which Schäffer obtained specimens in the 1750s. Other authors, starting with Louis Augustin Guillaume Bosc, 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 German freshwater fauna. He suggested that the genus name Apus be replaced by Triops Schrank as a bird genus had been described by Giovanni Antonio Scopoli under the name Apus [7]. Robert Gurney preferred the name Apus Schäffer [7]. In his 1955 taxonomic review of the Notostraca, Alan R. Longhurst supported Keilhack's genus name Triops over Apus [7]. 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) [7]. The head of Triops 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). 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 are easily visible through the shell covering of the head.

Triops shrimps differ from Lepidurus as the telson bears a pair of long, thin caudal extensions in Triops, while Lepidurus bears a central platelike process. They occur in vernal pools, which must last for at least 2 weeks for the triops to become fully adult. The pools often occur in deserts.Triops are theoretically immortal. They behave normally in water, swimming and eating, but during periods of drought, they shrink to a nonmoving, living ball. They can survive this way for 5 years, without moving or eating. When water returns, they slowly grow back into their normal form. Most species reproduce sexually, but some populations are dominated by hermaphrodites that 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 [4]. Triops eggs enter a state of extended diapause when dry and tolerate temperatures of up to 98 °C for 16 hours, while the adult cannot survive temperatures above 34 °C for 24 hours or 40 °C for 2 hours [5]. The diapause prevents the eggs from hatching too soon after rain; the pool must fill with enough water for the dormancy to be broken [5]. Only 24 hours after hatching, the young resemble miniature adults [1]. Some species are considered living fossils, with a fossil record reaching back to the late Carboniferous, 300 million years ago [2]; Triops cancriformis has hardly changed since the Jurassic, @ 180 million years ago [3]. The following species are recognised [8,[9]: Triops australiensis (Spencer & Hall, 1895); T. baeticus Korn, 2010; T. cancriformis (Bosc, 1801); T.emeritensis Korn & Pérez-Bote, 2010; T. gadensis Korn & García-de-Lomas, 2010; T. granarius (Lucas, 1864); T. longicaudatus (LeConte, 1846); T. mauritanicus Ghigi, 1921; T. newberryi Thomas, 1921 and T. vicentinus Korn, Machado, Cristo & Cancela da Fonseca, 2010. 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 [10].
  • 1. Belk, Denton Belk (2007). "Branchiopoda". In Sol Felty Light & James T. Carlton. 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. Hannum, Chip and Stuart Halliday. "An Introduction to Triops". MyTriops.com.
  • 3. Grimaldi, David A. and Michael S. Engel (2005). "Arthropods and the Origin of Insects". Evolution of the insects. Volume 1 of Cambridge Evolution Series. Cambridge University Press. pp. 93–118. ISBN 978-0-521-82149-0.
  • 4. Bell, Graham (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.
  • 5. Osborne, Patrick L. (2000). "Hot deserts and environmental factors". Tropical ecosystems and ecological concepts. Cambridge University Press. pp. 18–49. ISBN 978-0-521-64523-2.
  • 6. Scarborough, John (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.
  • 7. Møller, Ole S., 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. Hannum, Chip. "A Brief Overview of the Species". MyTriops.com.
  • 9. Korn, Michael, 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.
  • 10. Korn, Michael, 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.
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Triop (Tadpole Shrimp)

The Triop, or Tadpole shrimp is a theoretically immortal creature. When in water, it behaves normally, swimming and eating, but during periods of drought, it shrinks to an "egg", a nonmoving, living ball. It can survive this way for five years, without moving or eating at all. When water returns, it slowly grows back into it's normal forrm. These cruestaceans are commercially sold as "instant pets" much as Brine Shrimp (Artemia Salina) are sold as "Sea Monkeys"

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Ecology

Habitat

Triops occur in vernal pools. These pools must last for at least 2 weeks for the Triops to become fully adult. The pools often occur in deserts, such as the Outback Desert in Australia where Triops australiensis makes its home.

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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage

Barcode of Life Data Systems (BOLD) Stats
                                        
Specimen Records:318Public Records:311
Specimens with Sequences:318Public Species:11
Specimens with Barcodes:317Public BINs:32
Species:11         
Species With Barcodes:11         
          
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Barcode data

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Locations of barcode samples

Collection Sites: world map showing specimen collection locations for Triops

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Wikipedia

Triops

Triops is a genus of small crustaceans in the order Notostraca (tadpole shrimp). Some species are considered living fossils, with a fossil record that reaches back to the late Carboniferous, 300 million years ago.

Relatives and fossil record[edit]

The genus Triops can be distinguished from the only other genus of Notostraca, Lepidurus, by the form of the telson, which bears a pair of long, thin caudal extensions in Triops, while Lepidurus 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 specimens have been seen an estimated 300 million years ago,during the carboniferous period.. Fossils attributable to this genus have been found in rocks of Carboniferous age, an estimated 300 million years ago,[2] and one extant species, Triops cancriformis, has hardly changed since the Jurassic period (approximately 180 million years ago).[3]

Life cycle[edit]

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.[4]

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.[5] 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.[5]

Taxonomy[edit]

The name Triops comes from the Greek τρία (tría) meaning "three" and ὤψ (ops) meaning "eye".[6] The head of Triops 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.

Franz von Paula Schrank was the first author to use the genus name Triops,[7] coining it in his 1803 work on the fauna of Bavaria. Their German name was Dreyauge, which means 'three-eye' in English. 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.[7] 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'.[7] 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.[7] 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).[7]

Although the taxonomy of the genus has not been reviewed since 1955, the following species are recognised:[8][9]

Triops 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.[10]

See also[edit]

References[edit]

  1. ^ Denton Belk (2007). "Branchiopoda". In Sol Felty Light & James T. Carlton. 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. Retrieved October 4, 2010. 
  3. ^ David A. Grimaldi & Michael S. Engel (2005). "Arthropods and the Origin of Insects". Evolution of the insects. Volume 1 of Cambridge Evolution Series. Cambridge University Press. pp. 93–118. ISBN 978-0-521-82149-0. 
  4. ^ 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. 
  5. ^ a b 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. 
  6. ^ 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. 
  7. ^ a b c d e 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. ^ Chip Hannum. "A Brief Overview of the Species". MyTriops.com. Retrieved October 4, 2010. 
  9. ^ 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. 
  10. ^ 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. 
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