Wheel Animalcule: the Rotifer

Today's adventure was located in and around a small ball of greenery collected from an outdoor fish pond in Preston, Idaho. The small pond was mostly frozen over, but microscopic life was thriving nonetheless. Using my AmScope microscope and laptop, I located an odd-looking pond inhabitant, one I immediately dubbed 'Stranger.'

Turns out, 'Stranger' isn't that strange; In fact, this little guy is quite common in freshwater environments. This organism is a rotifer, a microscopic aquatic animal of the phylum Rotifera. Rotifers were first described in the 1600s, gaining the nickname 'wheel animalcules' due to the appearance of a rotating wheel. This rotating wheel is a crown of cilia called the corona, and isn't actually rotating. Rotifers are made up of 900-1,000 cells, and most are 200 to 500 micrometers long. They have specialized organ systems including a full digestive tract, muscle bands, cerebral ganglion, and a light-sensitive eyespot. Many rotifers are free to move around in their environment, but some, like 'Stranger', anchor themselves using toes at the end of their foot. Check out the anatomy of a rotifer below!

Photo credit: Lumen Learning

Rotifers are sexually dimorphic, meaning that female rotifers are quite different from male rotifers. Females are larger and liver longer, and are capable of parthenogenesis (reproducing asexually) and sexual reproduction.

All in all, a great discovery to start off the new year. Find a rotifer in a pond near you!

References:

Introduction to the Rotifera, www.ucmp.berkeley.edu/phyla/rotifera/rotifera.html.

Wright, Jeremy. “Rotifera (Wheel or whirling animals).” Animal Diversity Web, animaldiversity.org/accounts/Rotifer