For my most recent blog assignment, I watched “Open Ocean” produced by The Blue Planet. I learned a lot of fascinating information about predatorial fish and organisms in the ocean and their habitats. The video first discussed the striped marlin, which can grow to three meters long and can find fish they feed on up to 100 meters deep. Several marlins will prey on sardines and other small fish by rapidly scooping them in their mouths near the surface. The Sei Whale, another inhabitant of the deep, can get up to 14 meters long and 20 tons in weight. The Sei Whale utilizes the “scooping method” much like the marlins, and can rapidly ingest 10-30 fish in one gulp. These whales also have the unique ability to monitor what is going on at the surface, and can “pounce” on birds lingering too close to the surface. The video demonstrates how between the marlins and the whales, almost an entire school of sardines can be totally annihilated from the ocean food chain. Within a few short days, waters that were previously teeming with life are wiped out and the hunters must move on in search of their next meal.
The Manta Ray, opposite from the marlins and whales, feed off of plankton. They can be as long as 3 meters across from wing to wing. Manta Rays may travel for days before finding adequate food sources. Certain fish that emit their eggs into the water for fertilization, make an ideal meal for the Manta Rays. The Manta Rays’ mouths are like giant filters that can sweep through the egg-ridden waters, scooping up their meal and processing out what is worth keeping. One of the more endangered egg-bearing fish to this food chain, is the Yellow Fin Tuna. If the tuna’s eggs even survive, it takes up to two years for them to be fully formed into a fish. In three years, the egg could be a 3 meter long tuna, however only about one in a million survives this long! Thus this low survival rate contributes to international value of the Yellow Fin and their rarity. Plankton, nutrients, and small baby fish, get caught in the ocean current boundaries and can travel vast distances from where they have originally been produced. Because of this distribution, random parts of the ocean may become extremely fertile for plankton-feeding fish who then gather for days or weeks feasting on the local fare.
The complexity of the ocean’s ecosystem and food chain fascinate me. It is so strange to me that fish can be born near one continent and then transported through the current system to become a mature fish in a completely different location. It was apparent to me through the video that every fish in the ocean, no matter how big or small, is a part of the food chain. It seems like there is always another fish or organism a little bit bigger that is willing and able to devour those beneath it. It is also interesting to me that all of the ocean processes continue on their own and have for thousands of years without human intervention. The ocean seems like such a vast, mysterious part of our globe that will forever give us cause for research and curiosity.
