Ever feel like you’re just drifting through life? Well some tiny organisms living in fresh and sea water literally are. These often overlooked organisms are so small you can rarely see them with the naked eye but these animals are the basis for life in our oceans as we know it. They provide food for all the larger animals we know and love, allowing them to survive in watery environments.
Now, I should point out that plankton refers to any animal floating in water that is unable to move against the currents – this includes larvae of various species, krill, algae, and even large animals such as jelly fish. There are many species of plankton and most are very small and can only be seen with a microscope.
Check out this beautifully shot TED-ed video for a look into this microscopic world from the perspective of a sea creature! (bonus: if you watch until the end, there’s a talking fish)
When we visited Bamfield Marine Science Center this past weekend, we got to take part in what was called a “plankton tow” – we lowered a net with a special container at the end into the water and burned donuts in our boat while the net followed, capturing plankton. As we spun around in circles, we discussed two of the major groups of these organisms: zooplankton and phytoplankton.
Zooplankton, like most animals, consume other organisms to gain their nutrients, phytoplankton on the other hand, gain energy from sunlight and convert this energy into their food – much like plants do. Every day an interesting phenomenon occurs called a diel vertical migration, which literally means a migration moving in an up and down direction, occurring on a 24-hour cycle.
Using the power of poetry, I present to you the reason for this interesting migration cycle:
An Ode to the Migration of Zooplankton
As the day ends and down goes the sun,
the pale moon rises – thus, night has begun.
Now the small zooplankton make their way
to the water’s surface, to feast on their prey.
Since their food prefers it up top,
these little guys make this their nightly stop,
but only when dark, so they won’t be viewed
by birds and the fish by whom they’d be chewed.
As the sun climbs to mark a new morning
our tiny heterotrophs sense this as a warning
and drift below the surface of the sea
here, from most predators, they can be free
If you want to catch these critters yourself
be sure to have a tow-net on your shelf.
And if it’s daytime and these plankton you seek,
drop your net low, and pull it back for a peek.