Els dendrobranquiats (Dendrobranchiata) són un dels dos subordres de crustacis decàpodes, el menys nombrós i diversifica, però amb representants molt coneguts, com les gambes i els llagostins, especialment pel seu interès gastronòmic.
Les diferències amb els pleociemats, l'altre subordre, es basen en la forma i l'estructura de les brànquies. Els dendrobranquiats les tenen ramificades com les branques dels arbres. La majoria són nedadores, i habiten des de la zona litoral fins a l'abissal. També tots els dendrobranquiats tenen el cos deprimit lateralment.[1]
El subordre Dendrobranchiata (Bate, 1888), se subdivideix en dos superfamílies:
Comprèn cinc famílies:
Compren dues famílies:
Els dendrobranquiats (Dendrobranchiata) són un dels dos subordres de crustacis decàpodes, el menys nombrós i diversifica, però amb representants molt coneguts, com les gambes i els llagostins, especialment pel seu interès gastronòmic.
Les diferències amb els pleociemats, l'altre subordre, es basen en la forma i l'estructura de les brànquies. Els dendrobranquiats les tenen ramificades com les branques dels arbres. La majoria són nedadores, i habiten des de la zona litoral fins a l'abissal. També tots els dendrobranquiats tenen el cos deprimit lateralment.
Die Dendrobranchiata bilden eine Unterordnung der Zehnfußkrebse. Sie umfasst etwa 500 Arten, unter ihnen einige wirtschaftlich bedeutsame Zuchtgarnelen.
Wie bei allen Zehnfußkrebsen ist der seitlich abgeflachte Körper gegliedert in die beiden Tagmata Cephalothorax und Abdomen. Der den Cephalothorax bedeckende Carapax ist ein wichtiges Unterscheidungsmerkmal der Familien innerhalb der Dendrobranchiata. So besitzt etwa der Carapax in der Familie der Solenoceridae einen in dieser Unterordnung einmaligen Dorn knapp hinter den gestielten Augen. Vorne endet der Carapax im sogenannten Rostrum, der innerhalb dieser Unterordnung sehr variable Längen aufweisen kann.
Das Abdomen ist in den meisten Fällen länger oder etwa genauso lang wie der Cephalothorax. Die Pleura (seitlichen Fortsätze) des zweiten Segments (Somits) überlappen nicht die des ersten. Dies unterscheidet die Arten der Dendrobranchiata von den Garnelen der Caridea.
Die Dendrobranchiata besitzen an den ersten drei Schreitbeinen (Pereiopoden) Scheren. Exopoditen fehlen (Sicyoniidae, Sergestidae, Luciferidae), sind reduziert (Hymenopenaeus sp.), oder vorhanden. Die Schwimmbeine (Pleopoden) sind in der Familie der Sicyoniidae eingliedrig, in den restlichen Familien zweigliedrig. Das hinterste, zu Uropoden geformte Schwimmbeinpaar besitzt im Gegensatz zu vielen anderen Zehnfußkrebsen keine Diaeresis.
Charakteristisch für die Dendrobranchiata sind die namensgebenden Kiemen, die wie bei einem Baum verzweigt sind (griechisch „dendro“ Baum, „branchia“ Kiemen).
Die Begattung erfolgt meist nach einer Häutung des Weibchens, in der Nacht oder bei Sonnenuntergang. Balz und Paarung kann bis zu drei Stunden andauern. Das Laichen erfolgt ebenfalls nachts, einmal in einem Häutungszyklus oder mehrmals. Mit Ausnahme der Luciferidae betreiben die Weibchen keine Brutfürsorge, die Eier werden direkt abgeworfen.
Bereits in den ersten 24 Stunden schlüpfen die Nauplien, welche im Gegensatz zur Schwestergruppe der Pleocyemata frei schwimmend sind. Sie können nicht fressen und durchlaufen in 68 Stunden 5 bis 8 Nauplius-Stadien. Diese enden, wenn die ersten beiden Maxillipeden sowie ein Carapax entwickelt sind und der Telson zweigliedrig wird. Über die folgenden 5 bis 6 Zoea-Stadien entwickelt sich die Larve schließlich zur sogenannten Post-Larve, die sich erstmals mittels Schimmbeinen fortbewegt. Mit diesem Stadium werden auch erstmals die Scheren an den ersten drei Beinpaaren funktional. Über einige weitere Häutungen wird Adoleszenz erreicht.
Verbreitet sind die Dendrobranchiata weltweit in Meerestiefen von 200 bis 2000 Meter; hauptsächlich zwischen den Breitengraden 40°N und 40°S. Einige Arten der Sergestidae leben in Süßwasser.
Mit Ausnahme der planktischen Luciferidae sind die Dendrobranchiata Lebewesen des Benthos. Sie ernähren sich omnivor. So werden etwa Pfeilwürmer, Ostrakoden, Ruderfußkrebse, diverse Weichtiere und auch Detritus gefressen.
Die Dendrobranchiata werden unterteilt in zwei Überfamilien und sieben rezente Familien:[1]
Die Dendrobranchiata bilden eine Unterordnung der Zehnfußkrebse. Sie umfasst etwa 500 Arten, unter ihnen einige wirtschaftlich bedeutsame Zuchtgarnelen.
Dendrobranchiata is a suborder of decapods, commonly known as prawns.[3] There are 540 extant species in seven families, and a fossil record extending back to the Devonian. They differ from related animals, such as Caridea and Stenopodidea, by the branching form of the gills and by the fact that they do not brood their eggs, but release them directly into the water. They may reach a length of over 330 millimetres (13 in) and a mass of 450 grams (1.0 lb), and are widely fished and farmed for human consumption.
While Dendrobranchiata and Caridea belong to different suborders of Decapoda, they are very similar in appearance, and in many contexts such as commercial farming and fisheries, they are both often referred to as "shrimp" and "prawn" interchangeably.[3] In the United Kingdom, the word "prawn" is more common on menus than "shrimp", while the opposite is the case in North America. The term "prawn" is also loosely used to describe any large shrimp, especially those that come 15 (or fewer) to the pound (such as "king prawns", yet sometimes known as "jumbo shrimp"). Australia and some other Commonwealth nations follow this British usage to an even greater extent, using the word "prawn" almost exclusively.[3] When Australian comedian Paul Hogan used the phrase, "I'll slip an extra shrimp on the barbie for you" in an American television advertisement,[4] it was intended to make what he was saying easier for his American audience to understand, and was thus a deliberate distortion of what an Australian would typically say.
Together with other swimming Decapoda, Dendrobranchiata show the "caridoid facies", or shrimp-like form.[5] The body is typically robust, and can be divided into a cephalothorax (head and thorax fused together) and a pleon (abdomen).[5] The body is generally slightly flattened side-to-side.[5] The largest species, Penaeus monodon, can reach a mass of 450 grams (16 oz) and a length of 336 millimetres (13.2 in).[6]
The most conspicuous appendages arising from the head are the antennae. The first pair are biramous (having two flagella), except in Luciferidae, and are relatively small.[7] The second pair can be 2–3 times the length of the body and are always uniramous (having a single flagellum).[7] The mouthparts comprise pairs of mandibles, maxillules and maxillae, arising from the head, and three pairs of maxillipeds, arising from the thorax.[8] A pair of stalked eyes points forwards from the head.[9]
The carapace grows from the thorax to cover the cephalothorax, and extends forwards between the eyes into a rostrum.[9] This is only as long as the stalked eyes in Benthesicymidae, Luciferidae and Sergestidae, but considerably longer in Aristeidae.[9]
As well as the three pairs of maxillipeds, the thorax also bears five pairs of pereiopods, or walking legs; the first three of these end in small chelae (pincers).[10] The last two pereiopods are absent in Luciferidae and Acetes, but much longer than the preceding pereiopods in Hymenopenaeus and Xiphopenaeus.[11]
The thoracic appendages carry gills, which are protected beneath the carapace.[12] The gills are typically branched, and so resemble trees, lending the group its scientific name, Dendrobranchiata, from the Greek words δένδρον (dendron, tree) and βράγχια (branchia, gills).[13]
The pleon, or abdomen, is similar in length to the cephalothorax.[14] It has six segments, the first five bearing lamellar pleopods, and the last one bearing uropods.[15] The pleopods are biramous, except in Sicyoniidae, where they are uniramous.[11] The uropods and telson collectively form the tail fan; the uropods are not divided by a diaeresis, as they are in many other decapods.[16] The telson is pointed and is usually armed with four pairs of setae or spines.[16]
Most of the musculature of a prawn is used for bending the pleon, and almost all the space in the pleon is filled by muscle.[17] More than 17 muscles operate each of the pleopods, and a further 16 power the tail fan in the rapid backward movement of the caridoid escape reaction.[18] These muscles, collectively, are the meat for which prawns are commercially fished and farmed.[19]
The nervous system of prawns comprises a dorsal brain, and a ventral nerve cord, connected by two commissures around the oesophagus.[20] The chief sensory inputs are visual input from the eyes, chemoreceptors on the antennae and in the mouth, and mechanoreceptors on the antennae and elsewhere.[21]
The digestive system comprises a foregut, a midgut and a hindgut, and is situated dorsally.[22] The foregut begins at the mouth, passes through the oesophagus, and opens into a sac that contains the grinding apparatus of the gastric mill.[22] The hepatopancreas feeds into the midgut, where digestive enzymes are released, and nutrients taken up.[22] The hindgut forms faecal pellets, which are then passed out through the muscular anus.[23]
The circulatory system is based around a compact, triangular heart, which pumps blood into three main arteries.[24] Excretion is carried out through the gills, and by specialised glands located at the base of the antennae, and is mostly in the form of ammonia.[25]
Prawns may be divided into two groups: those with an open thelycum (female genitalia) and those with a closed thelycum.[26] In the open–thelycum species, mating takes place towards the end of the moulting cycle, and usually at sunset.[27] In closed–thelycum species, mating takes place shortly after moulting, when the exoskeleton is still soft, and usually occurs in the night.[28] Courtship and mating may take up to 3 hours in Penaeus monodon, while in Farfantepenaeus paulensis, mating lasts just 4–5 seconds.[28] Spawning may occur several times during the moulting cycle, and usually occurs at night.[29]
With the exception of Luciferidae, the eggs of prawns are shed directly into the water, rather than being brooded.[30] The eggs hatch into nauplius larvae, which are followed by zoea larvae (initially protozoea, and later mysis) and then a postlarva, before reaching adulthood.[30] The changes between moults are gradual, and so the development is anamorphic rather than metamorphic.[30]
Uniquely among the Decapoda, the nauplii of Dendrobranchiata are free-swimming.[30] There are five to eight naupliar stages.[31] The earlier stages have three pairs of appendages that are used for locomotion – two pairs of antennae and the mandibles. Later stages also have rudiments of other mouthparts, but the nauplius is unable to feed, and only lasts 24 to 68 hours.[30] The body ends at a two-lobed telson, and the beginnings of a carapace emerge at this stage.[31]
There are typically 5 or 6 zoea stages in Dendrobranchiata, divided into protozoea and mysis.[30] In the protozoea larvae, the antennae are still used for locomotion, but the mandibles become specialised for mastication.[31] All the thoracic somites (body segments) have formed, and a carapace is present, covering part of the thorax.[31] It is smooth in the family Penaeidae, but bears many spines in the family Solenoceridae.[31] The pleon (abdomen) is unsegmented in the first protozoea, and ends in a bilobed telson, which may be used for cleaning other appendages, or for steering.[31] By the second protozoea, segmentation appears on the pleon,[31] and by the third protozoea, which may also be called the metazoea, the uropods have appeared.[32]
By the mysis stages, the pereiopods (thoracic appendages) start to be used instead of the antennae for locomotion.[32] The larva swims backwards, with its tail upwards, spinning slowly as it goes.[32] The carapace covers most of the segments of the thorax, and claws appear on the first three pereiopods.[32] By the last mysis stage, the beginnings of pleopods have appeared on the first five segments of the abdomen.[32]
The post-larva or juvenile stage is characterised by the use of the pleopods for locomotion.[33] The claws become functional, but the gills are still rudimentary.[33] The telson is narrower and only retains traces of its two-lobed development.[33] Through a series of gradual changes over following moults, the animal takes on its adult form.[33]
Dendrobranchiata were traditionally grouped together with Caridea as "Natantia" (the swimming decapoda), as opposed to the Reptantia (the walking decapods). In 1888, Charles Spence Bate recognised the differences in gill morphology, and separated Natantia into Dendrobranchiata, Phyllobranchiata and Trichobranchiata.[34] Recent analyses using cladistics and molecular phylogenetics recognise Dendrobranchiata as the sister group to all other Decapoda, collectively called Pleocyemata.[35]
The cladogram below shows Dendrobranchiata's placement within the larger order Decapoda, from analysis by Wolfe et al., 2019.[36]
DecapodaDendrobranchiata (prawns) 
Stenopodidea (boxer shrimp) 
Caridea (true shrimp) 
Achelata (spiny lobsters, slipper lobsters) 
Polychelida (benthic crustaceans)
Astacidea (lobsters, crayfish) 
Axiidea (mud shrimp, ghost shrimp, or burrowing shrimp)
Gebiidea (mud lobsters and mud shrimp)
Anomura (hermit crabs and others) 
Brachyura (crabs) 
Before 2010, the earliest known fossil prawns come from rocks in Madagascar of Permo-Triassic age, 250 million years ago.[37][38] In 2010, however, the discovery of Aciculopoda from Famennian–stage rocks in Oklahoma extended the group's fossil record back to 360 million years ago.[39] The best known fossil prawns are from the Jurassic Solnhofen limestones from Germany.[38]
Living prawns are divided among seven families, five in the superfamily Penaeoidea, and two in the Sergestoidea,[2] although molecular evidence disagrees with some aspects of the current classifications.[40] Collectively, these include 540 extant species, and nearly 100 exclusively fossil species.[1] A further two families are known only from fossils.[1]
The cladogram below shows Dendrobranchiata's internal relationships of extant families (excluding Solenoceridae):[36]
Dendrobranchiata Sergestoidea Penaeoidea Dendrobranchiata comprises the following superfamilies and families:
The biodiversity of Dendrobranchiata decreases markedly at increasing latitudes; most species are only found in a region between 40° north and 40° south.[48] Some species may occur at higher latitudes. For instance, Bentheogennema borealis is abundant at 57° north in the Pacific Ocean, while collections of Gennadas kempi have been made as far south as 61° south in the Antarctic Ocean.[48]
There is a great deal of ecological variation within the suborder Dendrobranchiata. Some species of Sergestidae live in fresh water, but most prawns are exclusively marine.[33] Species of Sergestidae and Benthesicymidae mostly live in deep water, and Solenoceridae species live offshore, while most Penaeidae species live in shallow inshore waters, and Lucifer is planktonic.[33] Some species burrow in mud on the sea floor during the day and emerge at night to feed.[33]
Prawns are "opportunistic omnivores",[49] and their diet can include a range of food items from fine particles to large organisms. These may include fish, chaetognaths, krill, copepods, radiolarians, phytoplankton, nematocysts, ostracods and detritus.[49] Prawns eat less around the time of ecdysis (moulting), probably because of the softness of the mouthparts, and must eat more than usual to compensate, once ecdysis is complete.[49]
Prawns are an attractive food for predators, with a higher energy content than most other invertebrates.[50] The larvae are prey to comb jellies, jellyfish, chaetognaths, fish and other crustaceans (such as mantis shrimp and crabs), and only a tiny proportion survive.[51] Juveniles are targeted by a number of fish, cephalopods and birds; Litopenaeus vannamei juveniles experience 90% mortality in the 6–12 weeks they spend in Mexican lagoons, and this is thought to be due almost entirely to predation.[51] Adult prawns are less susceptible to predation, but can fall prey to some fish.[52]
Dendrobranchiata are of huge importance. While in some countries, such as the United States, production is almost entirely through fisheries, other countries have concentrated on aquaculture (shrimp farms), including Ecuador where 95% of production is farmed; some countries produce similar amounts from fisheries and aquaculture, including Mexico, China, India and Indonesia.[53]
Species from the family Aristeidae are important to deep-water fisheries, particularly in the Mediterranean Sea, where Aristaeomorpha foliacea is caught by trawlers.[53] In Brazil, Aristaeomorpha foliacea, Aristaeopsis edwardsiana and Aristeus antillensis are of commercial importance.[53] The shallow-water Penaeidae are of greater importance, however, and the most important species for fisheries is Fenneropenaeus chinensis, with a catch in 2005 of over 100,000 tons.[35]
The most important species for aquaculture are Marsupenaeus japonicus (Kuruma prawn), Fenneropenaeus chinensis (Chinese prawn), Penaeus monodon (giant tiger prawn) and Litopenaeus vannamei (whiteleg prawn).[35]
Dendrobranchiata is a suborder of decapods, commonly known as prawns. There are 540 extant species in seven families, and a fossil record extending back to the Devonian. They differ from related animals, such as Caridea and Stenopodidea, by the branching form of the gills and by the fact that they do not brood their eggs, but release them directly into the water. They may reach a length of over 330 millimetres (13 in) and a mass of 450 grams (1.0 lb), and are widely fished and farmed for human consumption.
Los langostinos o lancostadae son una categoría comercial de crustáceos decápodos del suborden Dendrobranchiata. Son nadadores, de color rosado con vetas amarronadas y caparazón semiduro. Su longitud es de entre 12 y 15 centímetros. Se los encuentra en los mares de todo el mundo.[1]
Los langostinos en su vida silvestre consumen materia vegetal y materia vegetal en descomposición (algas). Se alimentan además de productos animales como crustáceos microscópicos, restos de animales, restos de peces y carroña. Algunas especies llegan a consumir peces y gusanos.
En España se considera particularmente a los del género Penaeus, aunque el término también abarca especies de otros géneros.
Además de los dos géneros ya mencionados, las siguientes especies se denominan langostino:
Los langostinos o lancostadae son una categoría comercial de crustáceos decápodos del suborden Dendrobranchiata. Son nadadores, de color rosado con vetas amarronadas y caparazón semiduro. Su longitud es de entre 12 y 15 centímetros. Se los encuentra en los mares de todo el mundo.
Dendrobranchiata on toinen kymmenjalkaisten äyriäisten kahdesta alalahkosta. Alalahkon nimi Dendrobranchiata viittaa sen jäsenten puumaisesti haaroittuneeseen kidusten rakenteeseen (kreik. dendron ’puu’, branchia ’kidukset’). Tämä erottaa ne Pleocyemata-alalahkosta, jossa kidukset ovat haarattomat.
Dendrobranchiata-äyriäiset ovat katkarapuja. Niiden ruumis on pitkänomainen, jokseenkin liereä ja sitä luonnehtii vahva, lihaksikas pyrstöosa. Selkäkilpi (carapax) on suhteellisen pehmeä ja ohut, sen etureuna muodostaa sarvimaisen otsapiikin. Keskiruumiin jalat ovat ohuet, takaruumiin (”ravunpyrstön”) raajat taas ovat sopeutuneet uimajaloiksi. Tuntosarvet ovat useimmiten pitkät. Katkaravut yleensä liikkuvat pohjan tuntumassa, jotkut uivat vapaassa vedessä.
Katkarapuja on kuitenkin myös kymmenjalkaisten toisessa alalahkossa Pleocyemata. Tuon ryhmän ”aidot katkaravut” (Caridea-osalahko) muistuttavat Dendrobranciata-katkarapuja ulkoisesti, mutta eroavat mm. kidusrakenteen sekä lisääntymistavan suhteen. Dendrobranchiata-katkaravut laskevat munansa veteen, jossa tapahtuu ulkoinen hedelmöitys, ja jossa munista kehittyy nauplius-toukkia. Pleocyemata-rapujen munat taas kehittyvät naaraan pyrstön alla.
Dendrobranchiata-alalahko jaetaan kahteen yläheimoon, Penaeoidea ja Sergestoidea, ja edelleen seitsemään heimoon, joissa on noin 500 lajia. Useimmat ovat merieläimiä, jotkut elävät jokisuissa hyvinkin laimeassa murtovedessä. Penaoidea-ryhmän lajit ovat yleensä pohjaeläimiä, Sergestoidea-lajit taas pelagisia.[1]
Dendrobranchiata-katkarapujen Penaeidae-heimoon kuuluvat tärkeimmät vesiviljelyssä käytetyt katkaravut. Nämä ovat mm. aasialaisen keittiön peruselintarvikkeita. Kaikkein tärkeimmäksi lajiksi on 2000-luvulla nopeasti noussut Keski- ja Etelä-Amerikan Tyynenmeren rannikolla kasvatettava valkokatkarapu (Litopenaeus vannamei = Penaeus vannamei). Sen vuosituotanto 2012 oli jo yli kolme miljoonaa tonnia ja ylitti arvoltaan lohen viljelytuotannon arvon.[2][3] Toinen keskeinen laji on Indopasifisen merialueen tiikerikatkarapu[4] (Penaeus monodon), jonka vuosituotanto on miljoonan tonnin luokkaa. Tästä 80 % tulee vesiviljelystä, loput kalastuksesta. Tiikerikatkarapu kasvaa yli 30-senttiseksi ja puolikiloiseksi.[5]
Dendrobranchiata on toinen kymmenjalkaisten äyriäisten kahdesta alalahkosta. Alalahkon nimi Dendrobranchiata viittaa sen jäsenten puumaisesti haaroittuneeseen kidusten rakenteeseen (kreik. dendron ’puu’, branchia ’kidukset’). Tämä erottaa ne Pleocyemata-alalahkosta, jossa kidukset ovat haarattomat.
Dendrobranchiata-äyriäiset ovat katkarapuja. Niiden ruumis on pitkänomainen, jokseenkin liereä ja sitä luonnehtii vahva, lihaksikas pyrstöosa. Selkäkilpi (carapax) on suhteellisen pehmeä ja ohut, sen etureuna muodostaa sarvimaisen otsapiikin. Keskiruumiin jalat ovat ohuet, takaruumiin (”ravunpyrstön”) raajat taas ovat sopeutuneet uimajaloiksi. Tuntosarvet ovat useimmiten pitkät. Katkaravut yleensä liikkuvat pohjan tuntumassa, jotkut uivat vapaassa vedessä.
Katkarapuja on kuitenkin myös kymmenjalkaisten toisessa alalahkossa Pleocyemata. Tuon ryhmän ”aidot katkaravut” (Caridea-osalahko) muistuttavat Dendrobranciata-katkarapuja ulkoisesti, mutta eroavat mm. kidusrakenteen sekä lisääntymistavan suhteen. Dendrobranchiata-katkaravut laskevat munansa veteen, jossa tapahtuu ulkoinen hedelmöitys, ja jossa munista kehittyy nauplius-toukkia. Pleocyemata-rapujen munat taas kehittyvät naaraan pyrstön alla.
Dendrobranchiata-alalahko jaetaan kahteen yläheimoon, Penaeoidea ja Sergestoidea, ja edelleen seitsemään heimoon, joissa on noin 500 lajia. Useimmat ovat merieläimiä, jotkut elävät jokisuissa hyvinkin laimeassa murtovedessä. Penaoidea-ryhmän lajit ovat yleensä pohjaeläimiä, Sergestoidea-lajit taas pelagisia.
Les Dendrobranchiata[1] sont un sous-ordre de crustacés décapodes dont les représentants ressemblent à des crevettes.
Leurs branchies sont constituées d’un axe ramifié de manière complexe, alors que dans l’autre sous-ordre (les Pleocyemata) les branchies portent des filaments ou des lamelles simples. À quelques exceptions près, les Dendrobranchiata pondent leurs œufs directement dans l’eau où ont lieu la fécondation et le développement. L’éclosion libère une larve nauplius.
Ce sous-ordre a été créé par Charles Spence Bate (1819-1889) en 1888.
Selon World Register of Marine Species (31 décembre 2014)[2] :
Aeger elegans, une espèce fossile.
Les Dendrobranchiata sont un sous-ordre de crustacés décapodes dont les représentants ressemblent à des crevettes.
Dendrobranchiata Spence Bate, 1888 è un sottordine di crostacei decapodi[1], le cui specie sono volgarmente chiamate "gamberi" o "gamberetti". Ci sono circa 540 specie esistenti, divise in sette famiglie, e fossili che risalgono al Devoniano. Essi differiscono da animali affini, come Caridea e Stenopodidea, dalla forma della ramificazione delle branchie e dal fatto che non covano le uova, ma le rilasciano direttamente in acqua. Essi possono raggiungere una lunghezza di oltre 330 millimetri e un peso di 450 g. Sono ampiamente pescati e allevati per il consumo alimentare umano.
Anche se Dendrobranchiata e Caridea appartengono a diversi sottordini di Decapodi, sono molto simili in apparenza e in molti contesti – come l'agricoltura e la pesca commerciale – sono entrambi spesso indicati come "gamberi" e "gamberetti" in modo intercambiabile. Il termine "gambero" è anche liberamente utilizzato per descrivere qualsiasi grande gamberetto, anche se tecnicamente si riferisce alla specie Aristaeomorpha foliacea[2].
I Dendrobranchiata sono stati tradizionalmente raggruppati, assieme ai Caridea, come "Natantia" (il decapodi che nuotano), in contrapposizione ai "Reptantia" (i decapodi con piedi). Nel 1888, Charles Spence Bate ha riconosciuto le differenze nella morfologia delle branchie e separato Natantia in Dendrobranchiata, Phyllobranchiata e Trichobranchiata[3]. Analisi molecolari sulla cladistica e la filogenesi riconoscono Dendrobranchiata come il gruppo fratello a tutti gli altri Decapodi, collettivamente chiamati Pleocyemata[4].
Prima del 2010, i primi gamberi fossili provenivano da rocce in Madagascar del Permiano/Triassico, datate a 250 milioni di anni fa[5][6]. Nel 2010, però, la scoperta degli Aciculopoda in rocce del Famenniano in Oklahoma ha esteso la presenza di fossili del gruppo fino a 360 milioni di anni fa[7]. Di contro, i gamberi fossili più noti provengono dai calcari giurassici di Solnhofen in Germania[6].
Dendrobranchiata Spence Bate, 1888 è un sottordine di crostacei decapodi, le cui specie sono volgarmente chiamate "gamberi" o "gamberetti". Ci sono circa 540 specie esistenti, divise in sette famiglie, e fossili che risalgono al Devoniano. Essi differiscono da animali affini, come Caridea e Stenopodidea, dalla forma della ramificazione delle branchie e dal fatto che non covano le uova, ma le rilasciano direttamente in acqua. Essi possono raggiungere una lunghezza di oltre 330 millimetri e un peso di 450 g. Sono ampiamente pescati e allevati per il consumo alimentare umano.
Dendrobranchiata is een onderorde van kreeftachtigen uit de klasse van de Malacostraca (hogere kreeftachtigen).
Dendrobranchiata is een onderorde van kreeftachtigen uit de klasse van de Malacostraca (hogere kreeftachtigen).
Dendrobranchiata er en underorden av tifotkreps. De kalles «reker», men er bare fjernt beslektet med de vanlige rekene i norske farvann, som tilhører infraordenen Caridea.
Gruppen har fått navn etter de forgrenede gjellene, fra gresk dendron, «tre» og brankhia, «gjelle». Gjellene skiller Dendrobranchiata fra den andre underordenen, eggbærereker, (Pleocyemata). Et annet viktig trekk som skiller underordenene er at Dendrobranchiata slipper de befruktede eggene fritt ut i vannet, der de etter 24 timer klekkes til en frittsvømmende naupliuslarve.
Kroppen består av et hode-brystavsnitt (cephalothorax) og en bakkropp (pleon), og er som regel flattrykt fra sidene. Cephalothorax er dekket av et kraftig skjold, carapax. Spissen på carapax danner et horn, rostrum, som stikker fram mellom øynene. Cephalothorax har fem par gangbein (peripoder). Øynene sitter på stilker. Pleon består av seks ledd. På hvert av de fem første leddene sitter det ett par svømmeføtter (pleopoder). På det bakerste leddet er det festet en halevifte som består av ett par uropoder og haleleddet, telson. Noen arter har lysorganer på pleon.
Larvene gjennomgår mange stadier under utviklingen. Naupliuslarven blir til en zoealarve. Neste trinn er mysislarven, som minner om en miniatyrreke, men som har mange flere bein. Det siste trinnet er den dekapode larven, som har fem par gangbein akkurat som de voksne individene.[1]
De er for det meste utbredt i varme havområder mellom 40° nord og 40° sør. Noen arter finnes i havet lenger nord og sør og i familien Sergestidae er det noen ferskvannsarter.
Den eneste vanlige arten i norske farvann er rødflekkglassreke (Eusergestes arcticus), som finnes fra Skagerrak og nordover langs hele kysten. En annen art, den oseaniske Funchalia woodwardi, er funnet som tilfeldig gjest i nordlige deler av Nordsjøen.[2]
Artene i familiene Aristeidae, Benthesicymidae og Sergestidae lever hovedsakelig på dypt vann. De er enten bunnlevende, eller meso- eller bathypelagiske. De fleste artene i familien Penaeidae lever i grunne kystfarvann i subtropiske eller tropiske strøk. Artene i familien Solenoceridae finnes som regel på dypere vann lenger ut fra kysten. Familien Sicyoniidae lever ned til 200 m dyp. Familien Luciferidae er planktonisk.
Flere arter gjemmer seg i mudderet på bunnen om dagen, og blir først aktive etter mørkets frembrudd. Antennene, som kan bli tre ganger så lange som reka, brukes til å søke etter føde. De er opportunistiske i valg av føde og eter alt fra små partikler til store organismer. Føden kan bestå av fisk, pilormer, krill, hoppekreps, radiolarier, planteplankton, muslingkreps og detritus. De eter mindre i tiden rundt skallskifte, antakelig fordi munndelene da er bløte, og må ete desto mer når skallskiftet er ferdig.[1]
Dendrobranchiata har stor økonomisk betydning. Noen store arter i familien Penaeidae kalles tigerreker eller kongereker. På norsk blir de ofte feilaktig kalt «scampi». Greenpeace har dem på sin rødliste for sjømat som en ikke bør kjøpe. Fiske etter viltlevende arter gjøres som bunntråling og fører til mye bifangst. Oppdrett medfører ødeleggelse av store områder med mangroveskog, overfiske av viltlevende unge eksemplarer og omfattende brudd på menneskerettene.[3][4]
Det drives fiske etter mange arter, som Parapenaeus longirostris,[5] Aristaeomorpha foliacea og Aristeus antennatus i Middelhavet, Fenneropenaeus chinensis i Øst-Asia,[1] Farfantepenaeus aztecus[6] og Litopenaeus setiferus i Mexico og USA,[7] og Fenneropenaeus indicus i Det indiske hav.[8] Den mest fiskede rekearten i verden er den lille Acetes japonicus med en fangst i 2011 på 550 297 tonn.[9] Viktige arter i akvakultur er Marsupenaeus japonicus, Penaeus monodon, Fenneropenaeus chinensis og Litopenaeus vannamei.[1]
Boas delte i 1880 tifotkrepsene i to delgrupper: Natantia, svømmende dekapoder (reker) og Reptantia, krypende dekapoder (hummer, kreps, krabber og andre). Bate oppdaget hvor viktig oppbygningen av gjellene er og fordelte i 1888 Natantia på tre delgrupper: Dendrobranchiata, Phyllobranchiata og Trichobranchiata.
Dendrobranchiata i moderne forstand er redusert i forhold til Bates oppfatning. Mange studier viser at Dendrobranchiata er en naturlig gruppe, som er søstergruppen til Pleocyemata.[1]
En klassifikasjon fra 2009 angir følgende delgrupper under Dendrobranchiata. Utdødde grupper er merket med kors (†):[10]
En molekylærgenetisk analyse, også fra 2009, viser derimot at klassifikasjonen ovenfor bør endres. Sicyoniidae er en delgruppe av Penaeidae, og den nåværende Penaeidae bør derfor splittes i tre familier. Den genetiske forskjellen mellom Aristeidae og Benthesicymidae er så liten at de bør regnes til én familie.[11] Den hittil eldste kjente fossile arten, Aciculopoda mapesi fra devon, ble beskrevet i 2010 og plassert i en egen familie, Aciculopodidae.[12]
Dendrobranchiata er en underorden av tifotkreps. De kalles «reker», men er bare fjernt beslektet med de vanlige rekene i norske farvann, som tilhører infraordenen Caridea.
Dendrobranchiata Bate, 1888, é um clado de crustáceos caracterizados por brânquias ramificadas e por não incubarem os ovos. Pertencem a este grupo os camarões peneídeos e os sergestídeos.
Possuem o 3º par de pereópodes quelado, com exceção das espécies que o apresentam reduzido, e a pleura do segundo somito do abdómen não se sobrepõe à do primeiro. Saem do ovo com a forma nauplius e passam pelas fases larvares de protozoea, zoea e póslarva[1].
Dendrobranchiata Bate, 1888, é um clado de crustáceos caracterizados por brânquias ramificadas e por não incubarem os ovos. Pertencem a este grupo os camarões peneídeos e os sergestídeos.
Possuem o 3º par de pereópodes quelado, com exceção das espécies que o apresentam reduzido, e a pleura do segundo somito do abdómen não se sobrepõe à do primeiro. Saem do ovo com a forma nauplius e passam pelas fases larvares de protozoea, zoea e póslarva.
Dendrobranchiata Bate, 1888
Синонимы
Dendrobranchiata (лат.) — подотряд десятиногих раков. Противопоставляются второму подотряду десятиногих раков — Pleocyemata. Отличается от них разветвлёнными жабрами и тем, что откладывают яйца непосредственно в воду, а не вынашивают на теле.
Подотряд включает 540 видов в семи семействах. Ископаемые виды известны с конца девонского периода.
Dendrobranchiata (лат.) — подотряд десятиногих раков. Противопоставляются второму подотряду десятиногих раков — Pleocyemata. Отличается от них разветвлёнными жабрами и тем, что откладывают яйца непосредственно в воду, а не вынашивают на теле.
關於与「枝鰓亞目」名称相近或相同的条目，請見「枝鰓亞目 (消歧義)」。對蝦總科 Penaeoidea
櫻蝦總科 Sergestoidea
枝鰓亞目（Dendrobranchiata），是甲殼類動物十足目下屬的一個亞目，具有五對足。它現存540個物種，其最早的化石紀錄可追溯至泥盆紀。枝鰓亞目和蝦（真蝦下目）、蝟蝦（拳師蝦，蝟蝦下目）等其他甲殼類動物不同，它擁有枝狀的鰓，沒有育卵行為，而是直接將卵釋入水中。它的體長可達330毫米，重450克，是人類最廣為捕捉和養殖的蝦類之一。
枝鰓亞目（Dendrobranchiata），是甲殼類動物十足目下屬的一個亞目，具有五對足。它現存540個物種，其最早的化石紀錄可追溯至泥盆紀。枝鰓亞目和蝦（真蝦下目）、蝟蝦（拳師蝦，蝟蝦下目）等其他甲殼類動物不同，它擁有枝狀的鰓，沒有育卵行為，而是直接將卵釋入水中。它的體長可達330毫米，重450克，是人類最廣為捕捉和養殖的蝦類之一。
根鰓亜目（こんさいあもく、学名 Dendrobranchiata）は十脚目を2分する亜目の1つ。クルマエビ亜目とも呼ばれる。
もう一つの分類群・抱卵亜目より祖先的とされている。かつて十脚目は外見上の違いから、長尾亜目（エビ）・短尾亜目（カニ）・異尾亜目（ヤドカリ類、ヤドカリ・タラバガニなど）に分けられていたが、クルマエビ亜目は全て旧長尾亜目（エビ）に含まれる。
成体の鰓は細かく枝分かれした羽毛状の構造で、根鰓（こんさい）dendrobranch と呼ばれ、分類名もここに由来する。ただしユメエビ類の成体は鰓が無い。成体の大きさは数mmほどのユメエビ類 Lucifer から、30cmを超えるウシエビ Penaeus monodon、オオミツトゲチヒロエビ Aristaeopsis edwardsiana まで大きな差がある。
生殖腺はオスの第5歩脚基部、メスの第3歩脚基部にある。また、オスの第1腹肢内側には雄性生殖器（petasma : ペタスマ、ペタズマとも）、メスの第4・第5歩脚の内側に雌性生殖器（thelycum : セリカム）がある。特に多くの種を抱えるクルマエビ科を同定する際は、生殖器の形状は重要な手がかりとなる[1][2][3]。
クルマエビ亜目は受精卵を保護せず水中に放出し、放出された受精卵はプランクトンとして水中を浮遊しながら発生する。卵を保護しない分は小卵・多産で個体数をカバーする傾向があり、一般的にエビ亜目よりも一度の産卵数が多い。大型種のクルマエビでは産卵数が数十万に達する。また、子が卵から孵化する段階ではノープリウス幼生の形態である（エビ亜目はそれより一段階進んだゾエア幼生、または直達発生で孵化）。
の4段階の変態を経て稚エビになる。なおクルマエビ科のゾエア期をミシス mysis、サクラエビ科のプロトゾエア期をエラホカリス elaphocaris、同じくサクラエビ科のゾエア期をアカントソーマ acanthosoma と呼ぶこともある[2]。
2上科9科が分類され、うち2科は化石種のみで構成される[4]。ジュラ紀の地層から化石が発見されている。主に熱帯・温帯の浅海から深海に分布する。原則として海生だが、中には汽水域に生息するもの、さらには淡水域まで進入するものもいる。
下位分類群の和名、ラテン語名、記載者、記載年、おもな種類を以下に示す[1][2][3][4]。
Sergestoidea Dana, 1852
大きさは体長数mm-数cm程度だが、10cmを超えるオオサクラエビ Sergia tenuiremis (Krøyer, 1855) という種類もいる。5対の歩脚のうち後ろの第4・第5歩脚が退化している。海中を群泳する習性を持ち、生息海域は外洋・内湾、深海・表層など種類によって異なる。地域や種類によっては食用に漁獲される。
Penaeoidea Rafinesque-Schmaltz, 1815
大きさは体長数cmほどのものから20cmを超えるものまで種類によって異なる。5対の歩脚はいずれもよく発達する。漁業資源となるものが多い。
次の2科は化石種のみが知られる[5]。
以下に現生種を含む科を示す[5]。
現生種に関しては次のような系統樹が得られている[6]。ユメエビ科はこの系統解析に含まれておらず、現在でもその系統的位置は不確定である。
根鰓亜目（こんさいあもく、学名 Dendrobranchiata）は十脚目を2分する亜目の1つ。クルマエビ亜目とも呼ばれる。
もう一つの分類群・抱卵亜目より祖先的とされている。かつて十脚目は外見上の違いから、長尾亜目（エビ）・短尾亜目（カニ）・異尾亜目（ヤドカリ類、ヤドカリ・タラバガニなど）に分けられていたが、クルマエビ亜目は全て旧長尾亜目（エビ）に含まれる。
수상새아목(樹狀鰓亞目, Dendrobranchiata) 또는 근새아목(根鰓亞目)은 십각목에 속하는 2개 아목의 하나이다. 참새우류라고도 한다. 또 하나의 아목인 범배아목보다 더 원시적이다. 십각목은 외관상의 차이로 새우, 소라게, 게로 나눌 수 있지만, 수상새아목은 모두 새우에 속한다.
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