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Archaeognaths are small insects with elongated bodies bent into an arch shape and three long tail-like structures, of which the median filament is longest. They have flexible [[antenna (biology)|antennae]], large [[compound eye]]s that meet at the top of the head, and three [[ocelli]]. Their [[insect mouthparts|mouthparts]] are partially retractable, with simple chewing [[mandible (arthropod)|mandibles]] and long maxillary [[palp]]s.<ref name=IIBD />{{rp|341–343}}[[File:Rock bristletail dorsal.JPG|left|thumb|250px|Rock Bristletail Dorsal View<ref name="Cirrus Digital" />]]
Archaeognaths are small insects with elongated bodies bent into an arch shape and three long tail-like structures, of which the median filament is longest. They have flexible [[antenna (biology)|antennae]], large [[compound eye]]s that meet at the top of the head, and three [[ocelli]]. Their [[insect mouthparts|mouthparts]] are partially retractable, with simple chewing [[mandible (arthropod)|mandibles]] and long maxillary [[palp]]s.<ref name=IIBD />{{rp|341–343}}[[File:Rock bristletail dorsal.JPG|left|thumb|250px|Rock Bristletail Dorsal View<ref name="Cirrus Digital" />]]


Archaeognatha differ from Thysanura in being able to use their tails to spring up to {{convert|30|cm|in|abbr=on}} into the air. They are also unique in possessing small, articulated "styli" on the hind (and sometimes middle) [[arthropod leg|coxae]] and [[sternite]]s 2 to 9, which are sometimes considered to be rudimentary [[appendage]]s, as well as paired eversible membranous vesicles through which they absorb water.
Archaeognatha differ from Thysanura in being able to use their tails to spring up to {{convert|30|cm|in|abbr=on}} into the air. They are also unique in possessing small, articulated "styli" on the hind (and sometimes middle) [[arthropod leg|coxae]] and [[sternite]]s 2 to 9, which are sometimes considered to be rudimentary [[appendage]]s, as well as paired eversible membranous vesicles through which they absorb water. [[File:Tête de Trigoniophthalmus alternatus.jpg|thumb|Example of Compound Eyes (''Trigoniophthalmus alternatus'')<ref>[https://commons.wikimedia.org/wiki/File:T%C3%AAte_de_Trigoniophthalmus_alternatus.jpg Wikimedia Commons]</ref>]]


Further unusual features are that the abdominal sternites are each composed of three [[sclerite]]s, and they cement themselves to the substrate before [[ecdysis|molting]]. Like Thysanura, the body is covered with scales, with a thin [[exoskeleton]] that is susceptible to dehydration.
Further unusual features are that the abdominal sternites are each composed of three [[sclerite]]s, and they cement themselves to the substrate before [[ecdysis|molting]]. Like Thysanura, the body is covered with scales, with a thin [[exoskeleton]] that is susceptible to dehydration.

Revision as of 17:25, 21 February 2016

Archaeognatha
Temporal range: Devonian–Recent[1]: 320 
Rock Bristletail [2]
Scientific classification
Kingdom:
Phylum:
Subphylum:
Class:
Subclass:
Monocondylia

Haeckel, 1866
Order:
Archaeognatha

Börner, 1904
Families

The Archaeognatha are an order of wingless insects, also known as jumping bristletails. They are among the least evolutionarily changed insects, appearing in the Middle Devonian period along with the arachnids. They are known from both body and trace fossils (the latter including body imprints and trackways) throughout the remainder of the Paleozoic Era.[3] The name Archaeognatha is derived from Greek, archaeos meaning "ancient" and gnatha meaning "jaw". This refers to the articulation of the mandibles, which has a single condyle, where all higher insects have two. An alternate name, Microcoryphia, comes from the Greek micro, meaning "small", and coryphia, meaning head.

The order Archaeognatha has previously been combined with the order Thysanura; both orders possess three-pronged tails comprising two cerci and an epiproct.

The approximately 350 species in the two families are distributed worldwide. No species is currently at conservation risk.[4]

Description

Archaeognaths are small insects with elongated bodies bent into an arch shape and three long tail-like structures, of which the median filament is longest. They have flexible antennae, large compound eyes that meet at the top of the head, and three ocelli. Their mouthparts are partially retractable, with simple chewing mandibles and long maxillary palps.[1]: 341–343 

Rock Bristletail Dorsal View[2]

Archaeognatha differ from Thysanura in being able to use their tails to spring up to 30 cm (12 in) into the air. They are also unique in possessing small, articulated "styli" on the hind (and sometimes middle) coxae and sternites 2 to 9, which are sometimes considered to be rudimentary appendages, as well as paired eversible membranous vesicles through which they absorb water.

Example of Compound Eyes (Trigoniophthalmus alternatus)[5]

Further unusual features are that the abdominal sternites are each composed of three sclerites, and they cement themselves to the substrate before molting. Like Thysanura, the body is covered with scales, with a thin exoskeleton that is susceptible to dehydration.

Biology

Archaeognaths are found in a wide range of habitats, and are unusual among insects in that they can even be found in the Arctic, where they live in leaf litter and rock crevices. While most species are found in moist soil, others have adapted to chaparral, and even sandy deserts. They feed primarily on algae, but also lichens, mosses, or decaying organic materials.

During courtship, the males spin a thread from their abdomens, attach one end to the substrate, and string packages of sperm (spermatophores) along it. After a series of courtship dances, the female picks up the spermatophores and places them on her ovipositor. The female then lays a batch of around 30 eggs in a suitable crevice. The young resemble the adults, and take up to two years to reach sexual maturity. Unlike most insects, the adults continue to moult after reaching adulthood, and typically mate once at each instar. Archaeognaths may have a total lifespan of up to four years, longer than many larger insects.[1]

Role in Ecosystems

Needs more information: not much is known about archaeognaths' function in society (for example, how they help to break down leaf litter; any mutualistic relationships with other insects). Current research: [citation needed]

References

  1. ^ a b c Hoell, H.V., Doyen, J.T. & Purcell, A.H. (1998). Introduction to Insect Biology and Diversity, 2nd ed. Oxford University Press. ISBN 0-19-510033-6.{{cite book}}: CS1 maint: multiple names: authors list (link)
  2. ^ a b Cirrus Digital: Rock Bristletail - Family Meinertellidae
  3. ^ Getty, Patrick; Sproule, Wagner and Bush (2013). "Variation in Wingless Insect Trace Fossils: Insights from Neoichnology and the Pennsylvanian of Massachusetts". PALAIOS. 28: 243–258. doi:10.2110/palo.2012.p12-108r.
  4. ^ NC State University, ENT 425 | General Entomology | Resource Library | Compendium [Archeognatha]
  5. ^ Wikimedia Commons

External links