Most people have never heard of a rotifer, so let’s start from the beginning. If you put a drop of pond, lake, or even potted plant water under the microscope, you might notice little worm-like creatures crawling around. They move like inchworms, head to toe to head to toe. You might observe a little “heart” beating near their heads. And from time to time, when they stop moving, their head bursts open into what looks like a fuzzy toilet brush. Lucky you, you’ve spotted a rotifer.
Rotifers are simple animals that live in pretty much every aquatic environment you can think of on Earth. Some people have found them in their kitchen sink drain, others in gutters, and some others in thermal vents. Their bodies are built for filter feeding. Instead of a mouth like ours, they have a bushy, ciliated corona that creates vortexes in the surrounding area. Bacteria, algae, and even small ciliates are sucked in. And that “heart” isn’t a heart. It’s a jaw! And finally, everything gets passed into a big gut and digested.
Bdelloid Rotifers: All Females, No Sex
There are three classes of rotifers. Two of them have both a sexual and an asexual life cycle. One class, the bdelloidea, does not engage in sexual reproduction. In fact, there are no male bdelloid rotifers; they’re all females! Now, this is weird for one crucial reason. Asexual reproduction is an evolutionary dead end. No genetic diversity means no ability to adapt. So, how do they do it? These girls steal the DNA of other organisms, such as bacteria, plants, protozoa, fungi, and especially other bdelloid rotifers. About 10% of a bdelloid’s genome isn’t even rotifer DNA!
Dealing With Tough Times
Animals have different ways of dealing with environmental stressors. Rotifers are no different. When their home dries out, or there isn’t enough oxygen, or when conditions simply aren’t right, rotifers dehydrate themselves and roll into a tun. Basically, a little dried cocoon. Their genome fragments while in this dry state, providing protection from damaging radiation, chemicals, and temperatures. When things get better, rotifers rehydrate and go about their business. Scientists believe that this dehydration and rehydration process is the key to rotifers assimilating all that foreign DNA into their genomes.
Root For The Underdog!
Rotifers are the underdogs of the microscopic world. There isn’t much press on rotifers; therefore, the general public doesn’t know much about them. But when it comes to resilience and toughness, they’re just as tough, if not tougher, than tardigrades! They’re used in microplastic research, genetic research, and even parasite-control research. If you love rooting for the underdog, then we encourage you to read up on this fascinating little animal. And on our end, since we love underdogs too, we created a rotifer necklace. Buy it for yourself or for a friend. It makes an excellent gift for microbiologists, ecologists, geneticists, and anyone who also loves supporting the underdog.written by Science with Evie