October 17th, 2011

The video below is of a tiny rotifer called Conochilus.  It was taken through a microscope with a digital camera, while also being displayed on a SmartBoard for students to see.  This is a very engaging activity for Grade 6 students studying Biodiversity at the Blair Outdoor and Environmental Education Centre – you can hear their level of excitement in the background as they work at their own microscopes around the room.

The rotifers, or “wheeled animals” are a phylum within the animal kingdom.  There are about 2200 known species, 25 of which are colonial, only 9 of those being free-swimming, or planktonic, like Conochilus.  You can see the cilia rotating about the mouth of the animal, drawing water in to filter it for food.  You will also see them contract and spring back up on their stalks.  The colony is spherical with all the individuals’ stalks connected at the center.

Students also found this fabulous specimen of Stentor, a member of the Kingdom Protista. Protists are single-celled organisms.  It’s probably the best specimen of Stentor we have recorded with the camera. They typically anchor themselves to plants or debris on the pond bottom, filtering the water for food and oxygen but are able to swim, or float on water currents, from place to place.  Some species have a symbiotic relationship with tiny algae they have ingested, benefiting from the plant’s production of food through photosynthesis, the plant using nutrient wastes from the animal. Look for small green spots – the algae – inside Stentor’s body.