By: Elizabeth Farnham
Plankton are the most abundant organisms in the ocean and every time we enter the water we are covered head to toe in these fascinating creatures. It's easy to take these tiny creatures for granted, but it is important to understand their vital role in the marine ecosystem.
The word plankton was derived from the Greek adjective “planktos”, which means wandering or drifting. This is fitting for plants and animals that spend part of, or even all of their life drifting with the motion of the ocean.
Plankton are broken down into various sub-groups based on their lifestyle or ecological niche. Examples of these groups include phytoplankton, which are plant-like plankton, and zooplankton, which are animal-like plankton. Today we will focus on the importance of phytoplankton on our blue planet.
Let's begin by looking at the types of phytoplankton - diatoms and dinoflagellates.
This diatom is encased in a cell wall called a frustule.
Diatoms are the most common type of phytoplankton but their elegant glass-like, silica rich cell wall makes them unique. Diatoms are classified by structure into two types: pennate diatoms, which have bilateral symmetry and centric diatoms that have radial symmetry.
Here is a photo of a diatom taken with our microscope camera.
Ceratium longipes can be seen twirling around under the microscope - one of our favorites to observe!
The word dinoflagellate comes from the Greek word “dinos”, which translates to whirling and the Latin word “flagellum”, which translates to whip. These phytoplankton are slightly more active than diatoms because their flagella assist with locomotion. Many dinoflagellates are mixotrophic, meaning that they obtain energy in different ways - either through photosynthesis or by engulfing their prey!
Some species of algae may result in harmful algal blooms or HABs. This species of dinoflagellate is a target species for HABs because it can negatively impact fish respiration.
Now that we have discussed some of the basics, why should we care about these invisible creatures? Here are three important reasons:
1. Phytoplankton are the base of biological productivity in the ocean and support the marine food chain.
2. Phytoplankton provide at least 50% of the words atmospheric oxygen and some scientists estimate that it may contribute to up to 85% of the world’s oxygen.
3. Phytoplankton absorb carbon dioxide and convert it into usable sugars for energy. This process plays a role in the global carbon cycle by absorbing an enormous amount of CO2 from the atmosphere and transferring it to the ocean.
So next time you find yourself in the water, take a moment to think about the massive impact these microscopic organisms have!