Hemitrygon akajei ist eine Rochenart und lebt im nordwestlichen Pazifik von Thailand bis zum südlichen Japan. Meldungen über Vorkommen gibt es auch von Fidschi und Tonga.
Hemitrygon akajei kann eine Gesamtlänge von 2 m und eine Breite von 66 cm erreichen, die meisten erwachsenen Tiere sind aber nicht länger als 1 m. Er hat eine fünfeckige Brustflossen-Scheibe, die etwas länger als breit ist. Das vordere Ende der Scheibe ist spitz und wird von der dreieckigen Schnauze gebildet, die anderen Ecken sind abgerundet. Die Augen liegen in hervorgehobenen Sockeln, hinter ihnen liegen etwa doppelt so große Spritzlöcher. Zwischen den Atemlöchern befindet sich ein dicker Hautlappen. Die Zähne sind in Ober- und Unterkiefer jeweils in einer Art Quincunx-Muster gruppiert. Jungtiere und Weibchen haben abgerundete Zähne, erwachsene Männchen spitze. Der Schwanz ist peitschenartig und 1 bis 1,5 mal so lang wie die Scheibe. Der Rücken ist von rötlichem Braun, das zum Flossensaum hin in Orange übergeht. Der Bauch ist Orange-Rot. Wie alle Stechrochen hat sie einen Giftstachel.
Die Art lebt auf dem Kontinentalschelf im nordwestlichen Pazifik, bevorzugt im Flachwasser über sandigem Grund, aber auch in größeren Tiefen. Sie ernährt sich von kleineren Fischen wie der japanischen Sardine (Sardinops sagax melanostictus) und Krustentieren wie etwa der Sandgarnele. Hemitrygon akajei ist ovovivipar mit Würfen von bis zu zehn Jungtieren.
Die Rochenart wurde im Jahr 1841 durch die deutschen Naturwissenschaftler Johannes Müller und Jakob Henle unter der wissenschaftlichen Bezeichnung Trygon akajei beschrieben, später dann der Gattung Dasyatis zugeordnet. Bei einer Mitte 2016 erfolgten Revision der Dasyatidae wurde die Art in die Gattung Hemitrygon gestellt.[1]
Hemitrygon akajei ist eine Rochenart und lebt im nordwestlichen Pazifik von Thailand bis zum südlichen Japan. Meldungen über Vorkommen gibt es auch von Fidschi und Tonga.
The red stingray (Hemitrygon akajei) is a species of stingray in the family Dasyatidae, found in the northwestern Pacific Ocean off Japan, Korea, and China, and possibly elsewhere. It primarily inhabits shallow, sandy habitats close to shore, and has been known to enter brackish water. The red stingray has a diamond-shaped pectoral fin disc and gains its common name from its bright orange-red underside; there may also be patches of orange at various spots on its upper surface. Most individuals are no more than 1 m (3.3 ft) long.
Feeding mainly on crustaceans and bony fishes, the red stingray plays a key ecological role as an apex predator in its environment. Reproduction is aplacental viviparous, with females giving birth to 1 or up to 10 pups at a time. The red stingray is valued as food in Japan; large numbers are caught as bycatch and brought to market, which has seemingly led to a population decline in this unprolific species. As a result, the International Union for Conservation of Nature (IUCN) has assessed it as Near Threatened.
The original description of the red stingray was published by Johannes Müller and Friedrich Henle in their 1841 Systematische Beschreibung der Plagiostomen under the name Trygon akajei, based on an earlier account of "Pastinaca akajei" by Heinrich Bürger. A lectotype for this species was designated by Marinus Boeseman in 1947.[2] Other common names for the red stingray include brown stingray, estuary stingaree, Japanese red stingray, Japanese stingray, red skate, whip ray, whip stingray, and yellow stingray.[3]
The red stingray may be endemic to the northwestern Pacific Ocean;[1] it is found throughout Japanese coastal waters from Hokkaidō to Okinawa, and also occurs off Korea, mainland China and Taiwan.[4][5] This species has been reported from as far as Thailand, the Philippines, Fiji, and Tuvalu. However, whether these records truly represent D. akajei has yet to be determined.[1][3] The red stingray is commonly encountered in sandy areas close to shore and in bays at a depth of 10 m (33 ft) or more,[3][5] but also inhabits muddy flats, coral reefs, and estuaries.[6]
The red stingray can grow to 2 m (6.6 ft) long and 0.66 m (2.2 ft) across, though most do not exceed 1 m (3.3 ft) in length. The maximum recorded weight is 10.7 kg (24 lb).[1][3] It has a diamond-shaped pectoral fin disc wider than long, with nearly straight front margins converging to a triangular snout. The small eyes are slightly elevated, and followed by spiracles that are almost twice as large. There is a thick flap of skin between the large nares.[7] The teeth are arranged with a quincunx pattern into a pavement-like surface. Females and juveniles have blunt teeth, while adult males have pointed, recurved teeth.[5] There is a row of 3 papillae across the floor of the mouth, sometimes with up to 2 pairs of accessory papillae alongside.[4]
The tail is whip-like and measures 1–1.5 times as long as the disc is wide. A long, serrated spine originates in the first third of the tail, and is followed by a low dorsal keel and a ventral fin fold. Young rays have smooth skin, while adults have a patch of small dermal denticles between and behind the eyes, and a row of thorns along the midline of the back. There are 1–6 tubercles in front of the tail spine, and numerous small denticles behind. This species is plain brown above, often with yellow or orange coloring before the eyes, behind the spiracles, around the disc margin, and laterally on the tail in front of the spine. The tail darkens to nearly black towards the tip and on the ventral fin fold. The underside is white with bright orange-red patches.[4][7] The Mekong freshwater stingray (D. laosensis) is also characterized by orange ventral coloration and has some similar meristic counts to this species, but differs in disc shape, denticle coverage, and dorsal coloration.[8]
As an apex predator in nearshore demersal food webs, the red stingray plays a significant ecological role. Crustaceans are the most important component of its diet, followed by small bony fishes and then annelid worms, while molluscs are seldom consumed. In Tokyo Bay, important crustacean prey species are Crangon affinis for males, Oratosquilla ijimai for females, and Anisomysis ijimai for juveniles; the most important fish prey species is Sardinops melanostictus, followed by Conger myriaster.[5] Like other stingrays, the red stingray is aplacental viviparous.[3] During courtship, the male follows the female and bites at her pectoral fin disc, using his pointed teeth to gain a grip for copulation.[5] The litter size has been variously reported as only 1 or up to 10.[1][6] Males mature sexually at a disc width of 35–40 cm (14–16 in), and females at a disc width of 50–55 cm (20–22 in).[5]
Known parasites of the red stingray include the tapeworms Acanthobothrium macrocephalum,[9] Rhodobothrium pulvinatum,[10] and Tetragonocephalum akajeinensis,[11] the monogeneans Dendromonocotyle akajeii and Heterocotyle chinensis,[12][13] the leech Pterobdella amara,[14] the nematodes Porrocaecum laymani and Terranova amoyensis,[15][16] the copepod Trebius akajeii,[17] and the pranzia larvae of the isopod Gnathia capillata.[18]
The venomous tail spine of the red stingray is potentially injurious to humans.[3] The Ainu once used the dried tail spine, with the toxic sheath intact, as a weapon.[19] This species is an incidental catch of commercial fisheries targeting flounder and other bottom-dwelling fishes, using bottom trawls, gillnets, set nets, and line gear.[1] It is valued as food in Japan, especially in the Tokyo Bay area where it is consumed in autumn and winter; it may be prepared hard boiled, with miso soup, or as kamaboko.[3][5] However, the small size of the red stingray limits its economic importance.[3] Annual catches reported by Japanese fisheries have steadily declined from 20,000 tons in 1950 to varying between 3,959 and 5,388 tons from 1997 to 2004.[20][21] Such apparent depletion, coupled with continuing heavy fishing pressure and a slow reproductive rate, have led the International Union for Conservation of Nature (IUCN) to assess this species as Near Threatened.[1]
The red stingray (Hemitrygon akajei) is a species of stingray in the family Dasyatidae, found in the northwestern Pacific Ocean off Japan, Korea, and China, and possibly elsewhere. It primarily inhabits shallow, sandy habitats close to shore, and has been known to enter brackish water. The red stingray has a diamond-shaped pectoral fin disc and gains its common name from its bright orange-red underside; there may also be patches of orange at various spots on its upper surface. Most individuals are no more than 1 m (3.3 ft) long.
Feeding mainly on crustaceans and bony fishes, the red stingray plays a key ecological role as an apex predator in its environment. Reproduction is aplacental viviparous, with females giving birth to 1 or up to 10 pups at a time. The red stingray is valued as food in Japan; large numbers are caught as bycatch and brought to market, which has seemingly led to a population decline in this unprolific species. As a result, the International Union for Conservation of Nature (IUCN) has assessed it as Near Threatened.
La ruĝbruna rajo (Dasyatis akajei) estas rajoforma fiŝo el la familio de dasjatedoj, kiu videblas en riveroj kaj lagoj en sudokcidenta Gŭangŝjio de Ĉinio. Ĝi havas platan kaj romboforman korpan, kies larĝeco egalas trionon de ĝia totala longeco. Ĝia vosto plata kaj larĝa en la antaŭa parto kaj maldika en la malantaŭa parto estas 2-2,7-oble longa kiel ĝia korpo, kun venenaj segilformaj dornoj. Ĝi havas buŝeton sur la abdomeno, kun plataj dentetoj. Ĝiaj okuletoj estas iom elstaraj kun paro da akvoeniraj truoj malantaŭ si. La ido estas glata sen skvamoj. La matura fiŝo havas strion da tuberaj dornoj de sia malantaŭa kapo ĝis vostaj dornoj, kaj naĝilojn ĉe la abdomeno. Ĝi estas ruĝbruna.
La supre menciita specio estas unusola dolĉakva elasmobranka fiŝo de Ĉinio. Ĝi pezas 1-1,5 kilogramojn, maksimume 20 kilogramojn. Ĝi ofte sin kaŝas en akvofundo kaj moviĝas malrapide. Sen veziketo kaj pulmoj, ĝi havas 5 branktruojn. Ĝi nutras sin per malgrandaj fiŝoj, salikokoj kaj akvaj vermoj. Interesa estas ĝia kaptado de nutraĵo: Ĝi subite sin levas por ke ĉirkaŭaj fiŝoj kaj salikokoj kolektiĝu sub gian korpon Iaŭ la akvofluo, poste ĝi rapide malleviĝas por mortpremi la fiŝojn kaj salikokojn. Ĝi naskas ĉiufoje 7-8 fiŝidojn. Post sia naskiĝo la idoj sin alkroĉas al la brusto de la patrino kaj sendepende vivas nur post kiam ili plenkreskas.
Frue en Song-dinastio de Ĉinio jam estis registro pri produktado de tia fiŝo en Gŭangŝji. En 1962 ĉina anatomo pri fiŝo konstatis, ke dolĉakva kaj mara ruĝbrunaj rajoj apartenas al la sama specio. Sed kial la du "fratoj" vivas aparte? En la lastaj jaroj geologoj solvis la problemon: Pro terkrusta ŝanĝiĝo tiaj fiŝoj vivantaj en la riveroj Mingĝjang kaj Zŭoĝjang de Gŭangŝji ne povis reveni al maro kaj fariĝis nova specio post longa tempo.
Hemitrygon akajei es una especie de peces de la familia de los Dasyatidae y el orden de los rajiformes.
Los machos pueden alcanzar 200 cm de longitud total y 10,7 kg de peso.
Come peces y crustáceos pequeños.
Es un pez de clima tropical (39 º N-18 ° S) y demersal.
Se encuentra en el Océano Pacífico: desde el sur del Japón hasta Tailandia. También está presente en Fiyi y Tuvalu.
Es venenoso para los humanos.
Hemitrygon akajei es una especie de peces de la familia de los Dasyatidae y el orden de los rajiformes.
Dasyatis akajei Dasyatis generoko animalia da. Arrainen barruko Dasyatidae familian sailkatzen da.
Dasyatis akajei Dasyatis generoko animalia da. Arrainen barruko Dasyatidae familian sailkatzen da.
노랑가오리(red stingray)는 색가오리과에 속하는 물고기로 학명은 다시아티스 아카예이(Dasyatis akajei)이다.
몸길이 1m에 위아래로 넓고 납작하며 위에서 보면 거의 오각형이다. 목이 넓고 주둥이는 뾰족하며 눈이 작다. 몸빛은 녹갈색에 배끝이 노랗다. 꼬리에 긴 가시가 하나 있는데 길이가 약15cm 이기 때문에 매우 기다란 것 뿐만아니라 양쪽에 톱니가 있어 인간의 몸을 찌르면 몹시 아플 뿐만 아니라 가시 끝에 맹독이 있어 기절하고 심지어 죽을수도 있다. 난태생으로 5-8월 무렵 연안의 얕은 곳에 약 10마리의 새끼를 낳는다. 조개류나 갑각류 등의 딱딱한 껍데기를 부수어 속을 먹으며 작은 물고기도 잡아먹는다.
한국·일본·중국·인도양 등지에서 발견된다.
