Sea Creatures 101: Plankton: Teens of the Sea

Many people have heard of plankton. What do they do? They just drift along with the current, often not completely developed. They are not babies, and not adults. They’re teenagers.

Yes, plankton are the teens of the sea. They are in transition from babies to adults. Plankton can be plural or singular, depending on whether you are talking about a single plankton or a “bloom” of plankton. The sea carries the small living creatures along and as they travel some will grow into jellyfish, crabs, shrimp, krill, or other small animals. Some will never develop beyond the plankton stage. Some are plant-like.

The animal plankton, zooplankton, have two general classifications. Holoplankton stay in the plankton stage all of their lives. Jellyfish, krill, and a few other animals are in this category. Meroplankton are the true teens of the sea, changing as they travel in the current. These include crabs, starfish, sea urchins, clams, and coral. Zooplankton eat another type of plankton called phytoplankton.

Phytoplankton are plant plankton, and are the main producers of energy in this little plankton community. They draw energy from the sun, and change it into plant material. This type of photosynthesis is important for all animals living in the ocean, and for us too. Phytoplankton release oxygen as a by-product. These tiny, one-celled plants are reported to produce 80% of the oxygen on earth.

Dinoflagellates are a mix of plant and animal plankton. They can move like animal plankton and can produce their own food like plant plankton. “Red tides” happen when dinoflagellate populations get large. This is what is called a “plankton bloom.” The red color of dinoflagellates make the water appear red. Fish and shellfish that eat the dinoflagellates get a large dose of the dinoflagellate’s toxin, and can die. There is also a danger of toxic poisoning for humans who eat shellfish from these blooms.

Cleaning it all up for everyone in our plankton community are the bacterioplankton. They are the decomposers. They will break down the leftovers and digest them. That’s crucial in the plankton world. Break down and rebuild-that’s the Plankton Philosophy.

Many larger animals eat plankton. Basking sharks enjoy great amounts of specific types of zooplankton. The sulfide that zooplankton emit is easily picked up by basking sharks, and that's how the basking sharks find the plankton. In one hour, a basking shark can filter 330,000 gallons of water. That’s a lot of plankton!

Next time it’s a closer look at those mysterious jellyfish.

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