Range: Cosmopolitan Habitat: Almost any freshwater waterway Size: 0.0078-0.019 inches (200 to 500 micrometers) long Diet: Decaying matter and algae Threats: Crustaceans, insect larvae, and carnivorous plants Life span: Several weeks

Transcript:

Today on Animal Fact Files we’re talking about rotifers. Find any body of water, a stream, coastline, pond, puddle, even a bird bath, and you’re likely to find rotifers; though it’s unlikely you’ll actually see any. These microscopic animals average 200 to 500 micrometers in length, though the largest species’ are able to be seen with the naked eye as they can reach more than a millimeter in length. But that’s still tiny.

Rotifers are considered cosmopolitan meaning they can be found throughout the world, including Antarctica! Rotifers are mostly found in freshwater environments, though they can be seen in marine settings, and they are most abundant along water edges. The place where the scum all gathers along the side of a creek? That’s an excellent place to find rotifers. Heck, even just moist soil and moss can house these little creatures. Is your skin getting a little creepy crawly just thinking about it? Don’t worry, they can’t hurt you - it’s actually been suggested that they can help prevent disease!

There are more than 2,000 described species of rotiers and they are currently classified in three main classes. The largest class has about 1,500 identified species. Rotifers in this class are identified by their single reproductive organ. The second largest class has about 350 identified species. There are no known males from this class, and all members of this class reproduce asexually without fertilization. The smallest class has only two identified species and is currently considered the most prehistoric of the rotifer classes.

Though there are differences between these groups, as a whole rotifers can be broken down into a general body shape. Rotifers have a foot which they use to move around or attach themselves to surfaces - this sometimes looks like a tail. They also have a trunk in which most of their internal organs are located and which is where digestion occurs. Lastly, they have a head, which in many species is one of their most iconic features.

Rotifers are also known as wheel animals because most species have tons of tiny hair-like structures that form a crown-like structure called a ‘corona’ on their heads. These hair-like pieces are used to funnel water into the rotifer’s mouth, and while in motion look kind of like a rotating wheel. As tiny animals, rotifers eat tiny meals. Rotifers are generally considered omnivores and will eat small particles of decaying material as well as algae and sometimes even each other! In turn, rotifers are eaten by crustaceans such as shrimps and crabs, insect larvae, and even carnivorous plants!

Some rotifers live solitary lives. Like we mentioned before, some species don’t even need another individual to produce offspring. Other rotifers may live in colonies which stay together and may either float through to water or attach to a surface. Some rotifers produce eggs that may hatch into males. If this happens, the males will be tiny and unable to even eat, but they can fertilize eggs. Sometimes rotifers will even carry their eggs on their feet. And other rotifer species are able to withstand drying out, kind of like the tadpole shrimp we’ve discussed previously. In this state, rotifers may be pushed along by the wind and end up in completely different environments than where they started - such as backyard bird bath or rain gutters. In general, however, the active lifespan of a rotifer is usually just a few short weeks.

For more facts on rotifers, check out the links in the description. Thank you to Enrico Caponnetto and alterego for today’s request! Give a thumbs up if you learned something new today, and thank you for watching Animal Fact Files.