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Category: ZANIMLJIVOSTI
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Published on Thursday, 17 October 2013 19:48
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Written by Ivana
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Hits: 2858
Da biste preživeli u reci punoj pirana poželjno je da imate vrlo debelu, ili bar jaku krljušt. Upravo to je ono čime može da se pohvali velika riba arapaima, koja sa piranama deli vode Amazona. U želji da ustanove kako izbegava njihove ujede, naučnici su prvi put mikroskopski proučili njenu krljušt i ustanovili da predstavlja kombinaciju oklopa i amortizera.
Riba čiji je latinski naziv Arapaima gigas ima, naime, krljušt koja se sastoji od slojeva nalik na spiralno stepenište, načinjenih od kolagena i zaštićenih tvrdim spoljnim slojem. Izloženi pritisku, spiralni slojevi se rotiraju, prepliću i ugibaju, i na taj način amortizuju stisak piraninih oštrih zuba.
Istraživači veruju da je do nastanka ovih slojeva došlo tokom evolucije, dok se arapaima borila da preživi u vodama prepunim proždrljivih grabljivaca željnih njenog mesa.
Naučnici su, takođe, ustanovili da svaka krljušt na vrhu ima oko pola milimetra debeo tvrdi spoljni sloj, pod kojim leži dvostruko deblje meko unutrašnje jezgro, sastavljeno od već spomenutih spiralnih slojeva kolagena.
Tvrdi zaštitni sloj ima ulogu da štiti od prvobitnog kontakta s oštrim zubima, dok meko jezgro amortizuje snagu ugriza koji kroz krljušt pokušava da se probije. Pored toga, čak do 60 odsto krljušti se međusobno preklapa, što predstavlja dodatnu i konačnu zaštitu, jer su naučnici na simulatoru na kom su proučavali dejstvo ujeda ustanovili da piranini zubi čak i mogu da probiju jedan sloj krljušti, ali nikako dva.
Rezultati ovog istraživanja objavljeni su u naučnom časopisu “Nature Communications”, a autori studije, fascinirani lepotom, složenošću i efikasnošću amortizujućih spiralnih struktura, tvrde da im je želja da shvate “kako priroda razvija ove meterijale i da pokušaju da ih prekopiramo i načine nešto slično”.
- Možda čak i nešto što bi imalo bolja i efikasnija mehanička svojstva - zaključuju naučnici.

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