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Toxotes jaculatrix


Toxotes jaculatrix
Banded Archer Fish
高射炮
The banded archerfish (Toxotes jaculatrix) is a brackish water perciform fish of the archerfish genus Toxotes. It is silvery in colour and has a dorsal fin towards the posterior end. It has distinctive, semi-triangular markings along its sides. It is best known for its ability to spit a jet of water to "shoot down" prey. Larger specimens may be able to hit prey 2 to 3 metres (6 ft 7 in to 9 ft 10 in) away. The banded archerfish may reach the displaced prey within 50 milliseconds of its hitting the water.
The name (binomial as well as common) refers to Sagittarius the archer, because of the unusual method banded archerfish use to capture prey. Banded archerfish are found in Indo-Pacific and Oceanian waters, generally in river mouths and mangrove estuaries. They move between fresh, salt, and brackish water over the course of their lifetime, though not to breed. 
Banded archerfish have mouths adapted to spit jets of water over distance, usually to knock prey into the water. The banded archerfish shoots the jet of water by raising its tongue against the roof of its mouth, forming a tube. The opercula then close quickly, pressurizing water along the tube. Most archerfish are able to spit at a range of 150 centimetres (59 in), though some larger specimens may be capable of ranges of up to 2 to 3 metres (6 ft 7 in to 9 ft 10 in). When a prey is shot down, the banded archerfish begins to move towards the place where it will land within 100 milliseconds and can reach it within 50 ms of its hitting the water.
A study found that banded archerfish could be trained to hit moving targets at an accuracy rate of greater than 50%. According to this study, the ability to hit moving targets is a complex learned behaviour, and can be learnt from other members of the school. The study concluded that fish could shoot more accurately after observing other members of the school shooting.
The banded archerfish is able to hit targets with a high degree of accuracy, despite refraction of light in the water. It is believed that they are able to achieve this level of accuracy by positioning their bodies to shoot from directly under the intended target. However, other studies have found that banded archerfish are able to achieve great accuracy even at angles, suggesting that they are somehow able to compensate for refraction.This may also suggest that banded archerfish are capable of three-dimensional tasks
The banded archerfish inhabits the Indo-Pacific and waters off northern Australia, and less frequently those on the southern coast of Australia. It can be found from India eastwards to the Philippine Islands, southwards to Australia, as well as in waters off the Solomon Islands and the Indonesian Archipelago. It has been observed as far east as the New Hebrides (now known as Vanuatu). The banded archerfish occurs mainly in areas of brackish water. Mangrove estuaries are its primary habitat, though it occasionally moves upstream into freshwater rivers. It is associated with reefs and has been reported to occur near overhanging vegetation. While they may move between fresh and salt water during their life cycle, they do not do so to breed.
射水鱼俗称高射炮鱼,学名:Tax 射水鱼捕食otes jaculator,英文名:Archerfish,属于鲈形目射水鱼科,发现于1766年。射水鱼十分爱动、调皮,色彩鲜艳。身长只有20厘米左右,长着一对水泡眼,眼白上有一条条不断转动的竖纹,在水面游动时,不仅能看到水面的东西,也能察
射水鱼(13张)觉空中的物体。一旦有捕食对象,便偷偷游近目标,先行瞄准,然后从口中喷出一股水柱,将昆虫打落水中。它能把水射到3米多高,距离30厘米内的飞蛾很难逃命。它不仅能把苍蝇、蜜蜂、蝴蝶之类的小昆虫击落,还能把人的眼睛打伤。射水鱼这种本领,全靠一张嘴。它的嘴很特别,嘴沿上生有一道很细的槽,用舌尖能形成“水枪管”。只要把吸进的水从“枪管”中逼射出来,化成一束湍急的水柱,就能达到射击昆虫的目的。
射水鱼的体型近似卵形,身本侧扁,头长而尖,眼大体色呈谈黄,略带绿色。背鳍以前通常扁平,头尖、口大,背鳍与臀鳍均后位。体有黑色斑点或有黑色垂直带,视种类而异。在天然水域中,体长可达20-30厘米,但人工饲养的,以10余厘米为多见。
成鱼体长20-30厘米,人工饲养的在10厘米左右。体形接近卵形,头平吻尖,身体侧扁。体色银白鲜艳,有的呈淡黄色,略带绿色。体侧有六条黑色的垂直条纹,其中第一条过眼部,第二条在鳃盖上,第三条于鳃盖后由背至胸,第四条由背鳍起点处至腹部,第五条始于背鳍至体侧,第六条环绕尾柄。眼睛黑大而有神。背鳍后位与臀鳍对称,形状相似,呈半圆形,后端紧靠尾柄。尾柄短。尾鳍平截近似三角形。背鳍、臀鳍均有黑色宽边斑
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