Tuesday, November 26, 2013

Marine biology: seahorse hunt with sophisticated stealth - TIME ONLINE

beat quickly, even though they are miserable float: Seahorses are skilled hunters. The secret of their success hiding in her snout.

Seahorse A seahorse in an aquarium in California, USA (archive) | © Gabriel Bouys / AFP / Getty Images

seahorses always appear calm and graceful, graceful they bob up and down in seagrass beds. Nothing can disturb their sublime serenity. But all this is just a trick! The colorful fish are successful hunters, their fishing methods are highly specialized. A team of marine biologists at the University of Texas now has carefully examined the special shape of the seahorse head. For here lies their secret. The result can be read in the magazine Nature Communications : The animals are masters of camouflage, they can approach their prey, causing almost entirely without telltale water movements


This is advantageous because Seahorses are poor swimmers. Their prey, however, is lightning fast: Escaping copepods, for example, can travel 500 times their body length in one second. The small crabs are also always on the lookout for predators. With their sensitive antennae they still take slightest water movement true and also prevent attackers from early detection; within just four milliseconds to react to suspicious movements. The sedate acting seahorses must therefore be even more nimble, to fill you up – even if only for a fraction of a second



Among scientists, the fishing technique of the fish known as pivot feeding , the actual catch movement thus revolves around a pivot around a certain axis. This is the seahorse in the curved neck: To catch a prey animal, fast, the animals their head up and suck the victim into its mouth. A special chord construction acts like a spring under tension. So energy can be stored and implemented much faster in the head movement than would be possible with mere muscle power.

As far as the behavior of the unusual fish was already known. However, the skyrocketing seahorse head has only a very limited range. Lange was not clear how the animals of their prey ever come close enough to run their decisive blow can. They quickly move so only to the last millimeter. The hypothesis of biologists: Seahorses are adapted to conceal their movements, so as not to alarm the early sensitive cancers


Many aquatic organisms have specialized structures to perceive subtle undulations. Fish have it, for example the lateral line organ. In contrast to the sense of sight, allowing about an organ orientation in all directions of space. Whether the enemy back or front approaches from above or below, – he is betrayed by the waves that he proposes. Camouflage means in the sea so well, to prevent water movements as much as possible.

stealth mode with angled head

To test their hypothesis, the marine biologists had to Brad Gemmell as precisely detect which flows caused a seahorse when it slowly swims on its lining. With multiple cameras, they filmed the animals on the hunt in the experimental aquarium. Based on the movement of tiny particles suspended in water calculated a computer then a three-dimensional image of the water turbulence that arise around the body of the robber.

At the head of the sea horse, the researchers were able to first recognize no difference to other fish species: Relatively large, showy turbulence they found, also similar to the body. Only one point above the snout of the seahorse is significantly different in the pictures – the water around this place is hardly swirled from there no telltale undulations are unleashed. In the course of evolution, seahorse snout was perfectly adapted to cause only minimal currents. Seahorses so wear a cloak of invisibility – if only directly on the muzzle


observations explain the unusual pattern of movement of animals. They approach their prey obliquely from below, the head is always kept at a certain angle. Only then the seahorses are in stealth mode – and can outsmart the agile crabs. They kill so to speak, from the portable ambush. Who would have the pretty little creatures have expected such a thing.

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