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Features:
The Cookiecutter Shark combines many specialized features that enable it to carve out a living in the deep-sea. Like many mesopelagic sharks, it has an elongated body cavity filled with an enormous liver comprising as much as 35% of its total weight. The Cookiecutter’s liver is perfused with low-density oils which render the shark nearly neutrally buoyant over a wide range of depths and thereby saves energy by freeing it from the need to swim constantly to avoid sinking. It has very large eyes — the better with which to see potential prey — and a short, broad caudal fin that is ideal for rapid bursts of acceleration over short distances — that is, ambushing prey from close range.
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Hunting abilities:
To lure prey within range, the Cookiecutter Shark relies on its brilliant luminescence. Complex light-producing organs called “photophores” are scattered over the Cookiecutter’s entire body and are especially richly distributed on its belly and lower surfaces. A main function of this pattern of bioluminescent organs is to eliminate an animal’s shadow as seen from below, a common mesopelagic anti-predatory strategy known as “counter-illumination”. But there is a very curious fact about the distribution of photophores on the Cookiecutter Shark’s undersurfaces: they are completely absent from the region under the throat between the gill slits. It has recently been proposed that this dark patch that is bordered by luminescent organs may mimic the search image of many upward-looking pelagic predators. Thus, when a would-be predator approaches what appear to be a small shadow of a potential prey animal, it is brought within the striking range of the insidious Cookiecutter Shark and the predator has become prey.
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Humans who, by accident or by design, enter the open sea are not immune