Types of School in Cocos Island

Photo courtesy from scarletgeek.com

Before we proceed, we would like to clarify that the word “school” used in this article does not refer to an institution that caters to students and other educational endeavor that leads to a profession. What we mean is about the groupings of fish, where in the world of science, is termed as a school of fish.

It is a given fact that somewhere off the Pacific coast of Costa Rica lies an underwater world that houses an enormous diversity of fish and other marine wildlife. Not just in kind but also in quantity. While they thrive in a common body of water, they tend not to mix with each other. Instead, each species form a large group where they find safety in numbers and secure themselves against predation.

School of Fish

This is the most common type of marine wildlife grouping that is exclusive to fish. In Cocos island, you can see a variety of school of fish that inhabits different zones of the reef and the surrounding seas. Depending on the size of the fish that forms the school, a single grouping can comprise from a few hundred individuals and may go up to over a million. As a general rule: the smaller the fish, the bigger the quantity.

Ball of Sardines

Photo courtesy from fineartamerica.com

Once a year, small-sized fish called sardines swarms the waters of Cocos island as part of their annual global migration. Initially, when they arrive at the 12-mile protected zone of Cocos island, their formation is loosely aggregated. However, as they come close to the island, they are now chased by large predators like dolphins, tunas, seabirds and sharks.

If loosely aggregated, these predators will have a hard time consuming the sardines that is scattered everywhere. As a response to this perennial problem, predators have made a strategy to fully satisfy their gastronomic needs and get a bigger share of the pie.

In a simultaneous and coordinated action, these predators will try to compress the loosely aggregated sardines by swimming through their perimeter. In effect, thousands, if not millions of sardines will be compressed creating the so-called baitball. Once the predators have succeeded in compressing the sardines, a shallow water feast will commence. This is like an underwater fiesta where the main dish is sardines.

Of course, not all sardines will be consumed and the surviving population will continue their journey in the dynamic cycle of life. For more information, you can read our related article about Baitball.

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Vortex of Bigeye Trevally

Photo courtesy from Octavio Aburto

Generally named as Jacks, bigeye trevally are medium-sized fish that prefers to thrive in groups rather than being solitary. Of course, who wants to be lonely. In effect, they form a large aggregation. But as they are prone to individual predation, they find security in numbers where predators will have a hard time finding a single target.

To make their defense mechanism more effective, a school of jacks doesn’t just swim. They tend to simultaneously swim in a circular motion giving you a visual impression similar to a vortex in a tornado.

For more information, you can read our related article about bigeye trevally.

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Wall of Hammerhead Sharks

Photo courtesy from Wall of hammerhead sharks

Swarming the waters of Cocos island, hammerhead shark is the primary species featured in this World Class Diving Destination. Regardless of what dive site you explore, interacting with hammerhead sharks is a guaranty. The good thing: it’s not just one, not just ten, but hundreds of them.

Same with other shark species, hammerhead sharks patrol the oceanic water of Cocos island. When underwater, your initial interaction with them starts by observing them coming from the deep blue sea. As they come close to the reef where you are situated, they will start to traverse the ledges giving you an impression that they are forming a wall, as if telling you “this is our territory and do not to come near”.

While it is good for us to watch them pass by in a distance, some of these hammerhead sharks are similar to some naughty kids in our school. Instead of following the line, they go out of their way and comes close to you. Some have even experienced a very close encounter with just a few inches away. But do not be afraid. They come close to the reef not to take a bite from you. Instead, they drop by for a quick clean against body parasites and dead skin cells courtesy of cleanerfish.

For more information, please read our related about hammerhead sharks.

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Carpet of Whitetip Reef Sharks

Photo courtesy from www.sharkinformation.org

If we talk about sharks, what may come in to your mind are fast-swimming predators. However, this is not the case for whitetip reef sharks in Cocos island.

If you make a day-dive in a reef off the northern coast called Manuelita, you will see that the reef bottom is filled with motionless whitetip reef sharks. This is due to fact that they are in their relax mode. The vast reef area that is filled with motionless whitetip reef sharks lying close to the bottom will give you an impression that they look like a carpet.

However, their inactivity does not go around the clock. As the sun sets in and darkness starts to fall, these sharks become active in search for food. And the good thing with this, you can observe and witness their hunting skills as one of the famous dives offered in Cocos Island is Night diving with Whitetip Reef Sharks.

For more information, you can read our related article about whitetip reef sharks.

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Other types of School

Its not just fish that converge in to a large population. Other prominent groupings of marine wildlife can be seen in Cocos. Interactions with these group may sometimes require you to go deep or doesn’t require you to get wet where you can see them just above your boat.

Pod of Whales and Dolphins

Photo courtesy from San Diego Zoo Animals

The word “Pod” is used to specifically describe a group of whales or dolphins. While they are seldom seen alone, whales and dolphins tend to converge in to a large group. But the purpose of their grouping is different from a fish. If fish finds security in numbers against predation, whales and dolphin find success in numbers during feeding.

Despite their similarities, they also have some differences. Their migration pattern could be a prefect example of their differences where whales are known to follow a global migration path while dolphins tend to populate a certain body of water like Cocos island.

For more information, you can read our related article about whales.

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Army of Lobsters

Photo courtesy from Bill & Cathy Goocher

Large marine crustaceans also converge themselves in a group like lobsters. But contrary to the behavior of fish, dolphins and whales that are highly mobile, lobsters prefer to stay in one area. Aside from finding security in numbers, they take refuge in cracks, crevices or any structure that has an overhang.

The word “army” comes from their behavioral description during mating and spawning. During this season, they simultaneously come out of their hiding place to go to deeper waters. On their way to deep water, they form a line and crawl in an orchestrated motion that pretty much looks like the marching of an Army.

For more information, you can read our related article that features this large crustacean thriving in huge quantity while hiding under the crevices of Lobster Rock.

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Before we end this article, allow us to ponder on the saying no man is an island. It means that humans need each other to survive. Same with fish, as well as other marine creature, they need each other to survive. Survival for them would mean they eat, reproduce and pass on the genes for their next generation to continue. So, if this is the case, then we could also say: No fish is an island.

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Mission Blue: www.mission-blue.org

Scientific American: www.scientificamerican.com

Wikipedia: www.wikipedia.org

Video courtesy from wgreenti

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