Antony van Leeuwenhoek, a man of magnificent hair and considerable talent, was the pioneer of microscopy. Using a device he crafted himself he scrutinised all manner of unsavoury samples to see what miniature wonders they contained. Some of the first things he saw were the decidedly odd little animals known as rotifers. Even though he was the first person to see them he rightly knew they were some sort of animal; describing them as “animacules”. These animals are small all right (most are much less than 1 mm long), but if you want to see some for yourself they’re not difficult to find. In fact you can find them just about anywhere. The footage below shows the rotifer Rotaria rotatoria, lots of specimens of which were found in the detritus that had accumulated in the bottom of a rainwater-filled bucket. They’re about 0.4 mm long, so you need a microscope to see them, but they’re definitely worth having a close look at.
In the video, you can see what look like a pair of rotating wheels; the inspiration for the name ‘Rotifera’ (Latin for ‘wheel-bearer’). On its head the animal has a corona of beating cilia and it is the movement of these that deceives the eye into seeing a pair of rotating wheels. The ‘wheels’ are nothing more than an optical illusion.
You can see the vigorous vortices generated by these beating cilia funneling food (diatoms, etc) towards the mouth of the animal. In the next blog entry we’ll see how this tiny animals deals with its food.