Phytoplanktivore

A planktivore is an aquatic organism that feeds on planktonic food, including zooplankton or phytoplankton. For example; Titanichthys was the first massive vertebrate pelagic planktivore, with a lifestyle similar to that of the modern basking, whale, or megamouth sharks. Although plankton seem small and insignificant they are extremely important to the oceans. Plankton are actually responsible for producing 90% of the worlds oxygen due to the mass amounts of organisms in the waters of the world.

One major type of plankton that these organisms feed on are phytoplankton. Phytoplankton are usually photosynthetic one-celled plant organisms. These organisms are usually found near the surface of the water due to their need for light energy for their photosynthetic processes. Phytoplankton provide most of the oxygen that is in the water and provide a large amount of food for other organisms in the water column. Another major type of plankton is zooplankton which are "animal plankton". There are many different types of zooplankton, some are always in the plankton form and others only spend a period of their life cycle in the plankton form.

One example of a planktivore is the humpback whale (Megaptera novaeangliae). Humpback whales and other similar whales are classified as baleen whales. This means they consume all types of plankton and krill with the help of baleen. Baleen are bristle like structures in the whales mouth that hang down in place of teeth. They are similar to the bristles on a broom. Baleen whales take in large amounts of water into their mouths and all of the plankton and krill that was in the water is filtered through the baleen. This allows the whale to separate their food from the water column. The water is pushed out of the mouth and all of the remaining plankton become the whales meal. Another planktivore is jellyfish which are actually considered plankton themselves. The jellyfish sting the small plankton with their tentacles and bring the plankton to the center of their body where their mouth is found. It is also possible for the jellyfish to drift along in the current and eat the plankton that happen to find their way into the jellyfishes mouth. A feather duster is a segmented fan worm that also eat plankton in the water column. Their long arms look like feathers and each of the bristles helps the worm catch plankton in the water and brings the food to its mouth.

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Wikipedia