Field Notes

July 10, 2019

The Incredible Underwater World of Microorganisms

By Jed Harvey, research team member

I grew up reading fantasy novels and science-fiction books. I’ve dreamed of the beautiful architecture of  Rivendell from J.R.R Tolkien’s Lord of the Rings and feasted alongside Matthias in Brian Jacques’ Redwall series, but I have always found that the most wonderful and interesting things are found in the natural world.

Working at the Lilly Center, I get to spend a lot of time exploring creation. And since technology allows me to peer into the unseen world hiding in our lakes, I’m constantly finding and admiring a new land of amazing and interesting creatures to photograph, document and admire. I want to share this excitement with everyone, so here are three microorganisms I find fascinating and hope you will, too.

Daphnia (“Water Flea”)

Daphnia (from the order Cladocera in the phylum Arthropoda, for all the biology enthusiasts out there) is one common macroinvertebrate found here in Kosciusko County. They’ve been given the name “Water Flea” because of the way they move; they use their upper-most limbs (the large spiky ones near its eye) to quickly dart around in the water similar to how a flea hops around on land.

They are also zooplankton, meaning they eat algae and other small single-celled organisms. They do that by using their limbs to push water through their body so they can filter out and eat all the algae. Daphnia are a common zooplankton, most often found in the late spring when their lifecycle is at its peak. They are also tons of fun to watch swim around on the microscope slide!


My favorite type of algae (yes, I have thought about this) is without a doubt the green algae called volvox. Volvox aren’t fast-movers or interesting predators; they are just beautiful to look at.

Volvox live in large, coordinated colonies that appear completely spherical. Each sphere is one colony, and each colony has smaller spheres inside. All of the green dots on the outside are the individual volvox cells, and the smaller spheres on the inside are small developing colonies. Once the small child colonies are mature, the parent colony ruptures and releases the new volvox into the world.

They hardly look real. They look like something out of a sci-fi novel, yet they are content to stay in their habitats, living simple, photosynthetic lives.

Daphnia and volvox look like they are from another world, and in some ways they are! All around us is the world of the tiny, microscopic organisms, surviving and thriving in worlds too small to be seen by our eyes.

These creatures are swimming around in your lakes; but don’t worry, they’re harmless to humans and pets!