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WonderAnimal physics fact

Archerfish shoot insects off overhanging leaves with a jet of water. They hit the target even though light bends as it passes from air into water, so the insect is not where it appears to be.

Archerfish

BiologyScienceNature

The story behind the card

Archerfish live in mangroves and river mouths from India and South-East Asia to northern Australia. To shoot, a fish presses its tongue against a groove in the roof of its mouth and snaps its gill covers shut, forcing out a jet that can bring down prey up to about three metres above the water. Adults usually hit with the first shot, and they stay accurate from a wide range of angles. Young fish miss often at first and improve with practice; a 2006 study led by the German biologist Stefan Schuster found they can also learn by watching an experienced fish shoot. Schuster's team also showed that as soon as a struck insect starts to fall, the fish judges where it will land and swims straight there.

Türkçe oku
Okçu balıkları, suya sarkan yapraklardaki böcekleri ağızlarından fışkırttıkları suyla düşürür. Işık havadan suya geçerken kırıldığı için böcek göründüğü yerde değildir, ama balık yine de hedefi tutturur.

Okçu balıkları Hindistan ve Güneydoğu Asya'dan Kuzey Avustralya'ya kadar mangrov bataklıklarında ve nehir ağızlarında yaşar. Balık, atış yaparken dilini damağındaki ince bir oluğa dayar ve solungaç kapaklarını birden kapatır; oluktan fışkıran su, yüzeyin üç metre kadar yukarısındaki avı bile düşürebilir. Yetişkinler çoğunlukla ilk atışta vurur ve farklı açılardan nişan alsalar da isabetlerini korur. Yavrular başta sık sık ıskalar, deneye deneye ustalaşır. Alman biyolog Stefan Schuster'in ekibinin 2006'da yayımladığı bir çalışmaya göre, deneyimli bir balığın atışlarını izleyerek de öğrenebilirler. Aynı ekip, vurulan böcek düşmeye başlar başlamaz balığın onun nereye düşeceğini kestirip doğruca oraya yüzdüğünü de gösterdi.

Sources and further reading

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