The Coconut News – Hunting and Feeding in Palau

トムのココナッツニュース−パラオから。テーマは捕食です。下のビデオを見てみて下さい☆

March 1st, 2011

By Tom Osborn: Underwater Cinematographer and PangeaSeed Field Correspondent

Food. We all need it. Every living being on our planet needs food to survive including ourselves. However for animals (particularly marine life), gathering food is not a simple case of popping down to the local super market and picking out a favourite dish. They have to fight for their food and use all the inherent hunting and feeding instincts they have to survive. The marine environment has a very delicate food chain which, if sufficiently disrupted will create consequences not just damaging to the marine environment, but to life on land too.

This past month in Palau we have been seeing a swarm of feeding and hunting activity taking place among the many dive sites visited every day. From Manta Rays feeding on tiny plankton, to giant bait balls being chased over coral reefs by sharks. It certainly has been an exciting month to witness the underwater world at its most pure and primal. Underwater, when feeding behaviour begins, often many fish will form into thick schools for feeding efficiency or for protection from bigger fish trying to feed on them. Parrotfish have been seen a lot this past month schooling together to feed over large portions of Palau’s coral reefs. These hard beaked fish feed on algae that grow on the surface of coral. They swarm over the reef almost like a giant, living bulldozer leaving a trail of stirred up destruction in their wake. . Almost all species benefit from other species feeding patterns. Hawksbill and Green Sea Turtles will follow the path of disruption caused from feeding parrotfish and enjoy the easy meal of stirred up coral that they feed on. This is one of many examples of how vital the feeding behaviour of one species is to another in the marine environment.

When Parrotfish spawn they release thousands of tiny eggs that are then fertilized by the males. Many of these tiny eggs will never become fertilized and instead drift in the open water to become part of plankton. Plankton acts as a food source for many of the underwater worlds larger creatures such as Manta Rays.

Manta Rays are plankton feeders. They can been seen regularly in Palau feeding in great numbers, sometimes 10 – 20 Mantas feeding at once. There is a popular dive site in Palau called German Channel, famous for Manta Rays. When the tide is just right the channel acts as a funnel and a concentrated dose of plankton flows through. This is when the Manta Rays feed. Swimming through this plankton bloom with their mouths fully open allows them to consume as much plankton as they can. Sometimes when a Manta discovers a spot where the plankton is particularly thick they can be seen performing huge loops for greater feeding efficiency. Conditions are not always right for a steady flow of plankton to flow through German Channel so it is imperative that when feeding is possible, the Manta Rays are able to take full advantage of the feeding opportunity. This is common with much of the marine life.

Napoleon wrasses are very opportunistic predators. They can feed on almost everything from small crustaceans like crabs or lobster to octopus and even small fish. Recently I filmed a Napoleon catching and eating a Moorish Idol. After the Napoleon had caught and seemingly killed the colourful fish he swam above the reef for several minutes.  The mouth of the Moorish Idol was sticking out from between the Napoleons fat lips like a tiny aquatic cigarette before he managed to gulp it down. You could actually hear the noise of the Moorish Idol being crunched up inside the Napoleons mouth while it was being consumed.

The sharks of Palau have been witnessed enjoying much feeding frenzy this month also. White tip reef sharks can often be found with the front of their body’s buried into tight gaps in the reef, frantically twisting and twirling around trying to get at some unfortunate prey hiding inside. Often hunting together in small schools with other fish such as Napoleon wrasse, Giant traveli and even moray eels. This is another great example of how different species often work together for a common goal. Being thin, long and flexible a Moray eel can swim into tiny holes in the coral reef and chase lurking fish out from their safe zones. Once on the exposed reef the prey is then vulnerable to the hunting white tip reef sharks that will try and catch these fish with lightning speed. Any other species in the feeding posy such as Giant Traveli or Napoleon Wrasse will then try and pick up any of the scraps left over from the hunt.

Grey Reef sharks too have been seen chasing big schools of scad and surgeonfish across the reef. The sharks would mass together in promising numbers and try their best to split the schooling fish into smaller groups making them more vulnerable to attack. Occasionally the Grey reef sharks would work together and drive the schools of fish into shallow water. This makes it easier for the sharks to catch their prey as it cuts off one angle of escape for they’re soon to be meals.

Sharks are at the top of this delicate food chain. They are the top predators and their feeding behaviour controls the number of fish lower down this food chain. The importance of sharks in the marine environment is monumental. If sharks worldwide continued to be hunted for their fins then obviously there will be fewer sharks in our oceans. With less sharks in our oceans, species lower down the food chain will then be able to flourish to proportions not intended by nature. On the surface this may not seem like a problem but if you look closer you can see that less sharks could have devastating consequences for life on earth.

Algae on the whole accounts for over 80% of the global oxygen on our planet. As mentioned before, parrotfish eat mainly algae that grow on coral reefs. If there are less sharks their will inevitably be more numbers of smaller fish lower down the food chain such as parrotfish and other algae feeders. More algae feeders will result in fewer algae for our oceans. The less algae and consequentially the less oxygen can be made for the planet. It is a simple concept to understand yet a concept being largely ignored by almost every country in the world, especially the country’s profiting from the shark fin trade. To disrupt the number of top predators in a food chain can never lead to any good future, for anyone. Sharks have dominated and controlled the marine environment for thousands of years dating back to the time of the dinosaurs. A healthy marine environment is imperative for a healthy planet. Sharks have been a key species in maintaining a healthy planet for millennia. Never has this marine environment been more at risk and seen such devastating changes as it has in the past 100 years, since man has really made its impact felt. But people can make a difference. Recent dramas in Egypt prove that. When enough people work together for a common cause anything is possible. Support for organisations like PangeaSeed is vital for a brighter future. We can make a difference. Its simple, support our oceans and support ourselves.

Photo Copyright Tom Osborn

Video Copyright Tom Osborn, Ocean Wonders Productions, & PangeaSeed 2011

Ocean Wonders Productions


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