![]() ![]() Copepods are a favourite prey and it actively searches for their flashes in the darkness. It's the size of a pea, but that's enormous for an ostracod. The most sensitive eyes in the deep sea belong to an ostracod called gigantocypris. Other prey animals such as copepods have developed tactics to use bright or flashing lights to communicate with one another and confuse their predators, allowing them precious moments to get away unharmed. A shrimp senses a threat and spins in the water, releasing a bioluminescent glue that startles the fish and leaving it illumiated in the dark and vulnerable to its own predators. Narrated in Filipino by award-winning documentarist Kara David, BBC’s “The Blue Planet: Open Ocean” airs this Saturday, September 15 on GMA News TV Channel 11.Bioluminescence is useful as an escape strategy as well as for attack. It is a mammalian luxury that guarantees that only the most successful individuals will breed, ensuring that these toothed whales can continue to evolve to match the challenges of life in the open ocean. Intelligent, warm-blooded and with a large energy store of blubber, the whales can take time off from hunting to compete socially. ![]() In the Mediterranean coast of Spain, several hundred short-finned pilot whales gather to breed. But not all journeys are in search of food – the other imperative for survival is successful breeding. The survival odds rest on those predators who can efficiently move on, covering the countless miles at a low energy rate before finding yet another suitable feeding area. As quickly as they form, the ideal hunting conditions can melt away. Oceanic conditions change day by day, so today’s feeding hotspot may not be any good again for years to come. Oceanic predators do not always head to the same area each year. Gliding effortlessly across the ocean, they watch for signs that the dolphins are feeding then the elegant shearwater can dive several meters below the ocean surface to catch the mackerel it needs to feed its chicks. In the Azores, Corey’s shearwaters come in their millions every year, waiting for dolphins. Dolphins use their group skills to increase their chances of locating food. Even more bizarrely, the sunfish present their sides at the surface, actually encouraging a seagull to come and peck parasitic worms from their bodies! Perhaps the best solution for oceanic life is to be large and powerful enough to travel wherever you please. A floating giant kelp becomes an oasis and a cleaning station, where a group of giant sunfish visits to get parasites picked off by half moon fish. Larval trigger fish grow up under the shelter of drifting debris. Flying fish locate flotsam by sound and then use it to spawn on. In the open ocean, any manner of floating flotsam is a huge fillip to the survival chances of both plankton and small fish. How, then, does life exist in the open ocean? This Saturday, BBC’s “The Blue Planet” explores this most challenging of all the ocean’s habitats, where survival rests on knowing where to look and how to get there without using too much energy. There is nothing save the burning sun above and the blackened abyss below. The sea bed is a staggering eight kilometers down and the nearest land is 500 kilometers away. Endless blue stretches in every direction. ![]()
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