December 29, 2015

Heliozoa sun-animacule

Photographers: John Stetson; Jeff Small 
Summary Authors: John Stetson; Stu Witmer

What’s not to love about Heliozoa? It looks like the Sun. It has the Greek word for Sun in its name. It is often called a sun-animalcule. Animalcule, by the way, is a term coined by Antonie Van Leeuwenhoek, the curious cloth merchant and lens-making hobbyist, who went on to become the father of microscopy.

How they eat is particularly interesting and worthy of a leading role in a science-fiction movie: Heliozoa use their axopods, the microtubules that radiate outward, to attach themselves to algae and other microorganisms. The meal is then stunned and turned into mush as the nutrients are sucked back through the tubes to the 40-micron-sized center of the creature.

In the background you can see a series of single-cell organisms, plankton, that form star-shaped colonies. They, too, have a heavenly name, Asterionella. Picture taken June 9, 2015.