#didinium

Journey to the Microcosmos- We Recorded Too Much Slow Motion Footage So Here's a Bonus Video

“The paramecium is the consummate model organism. It's a protozoan that is both easy to grow and easy to study, which means that microbiologists have been able to learn all sorts of secrets about eukaryotic life by watching them. You might even call the paramecium a hero in our pursuit of knowledge. But just as heroes in stories have enemires, the paramecium has its own foe. And it is this strange critter. No, not the big eggplant-shaped looking this. The smaller one, the one that looks a bit like a swimming okra. This is didinium, though it wasn't always called that. When Otto Friedrich Muller first described it in 1786, he thought he was observing a Vorticella, and so he named it Vorticella nasuta. Almost a century later, Samuel Friedrich Stein would change its name to Didinium.”

Journey to the Microcosmos- Didinium: The Paramecium Hunter

“In the early 20th century, scientists added ink to jelly just so they could slow the didinium down and follow this path. The microbes's seemingly aimless trajectory helps the didinium cover a wide range space in a short amount of time. Think of it compared to another skilled hunter we watched recently, the lacrymaria olor, which sends its neck out into all directions to maximize the odds of encountering something. The didinium is doing something similar but instead of extending its neck, it's sending its whole body into different directions.”

Journey to the Microcosmos- Didinium: The Paramecium Hunter

CC: And that speed is a big reason why didinium is so effective. As it zips around the microcosmos, it will bump into things that don't happen to be food. And when it does, it politely backs up and moves on. But if its proboscis makes contact with something edible, then the didinium goes to work seizing its prey with its proboscis, paralyzing it, and then eating it. And while it is known to consume other organisms, what didinium really really likes to eat are paramecium. It doesn't matter that a paramecium might be size times its size, the didinium is here for a meal and it will gladly expand itself around the paramecium to swallow it. But as you can see, this is not a smooth process. The didinium is still moving and bumping around as it consumes the paramecium, and for a while, it's hard to even tell where predator ends and the prey begins. The only real didinium-like thing about it is the spiral path it still takes as it eats and eats and eats. But eventually it settles back into its more awkward-looking self.

Journey to the Microcosmos- Didinium: The Paramecium Hunter

“So protist have evolved these various appendages that allow them to move in a viscous environment. And that's because movement is essential, whether it's within a confined area or freely through space. It takes hunters to their prey, and it takes prey away from their hunters.”

Journey to the Microcosmos- Water Is Thicker When You’re Smaller

Images Originally Captured by Jam’s Germs

“Like it's paramecium foil, the didinium is a ciliate. But at first glance, it doesn't seem like it should be much of a problem. For one thing, paramecium can just get so much larger than a didinium. Plus, the didinium is just weird-looking. In fact, between the paramecium and the didinium, the didinium is the one that actually looks like food. We compared it to an okra earlier, but at other times it looks more like a stretched out acorn. And the pointier bit looks like a jalapeno stem. Of course, it is not a stem, it is the didinium's proboscis, which means that is the front of the organism.”

Journey to the Microcosmos- Didinium: The Paramecium Hunter

Images Originally Captured by Jam’s Germs

“So incredible is the didnium's appetite that scientists have observed it eating a pair of dividing paramecium. They've also occasionally been observed exploding from eating too much. So there are hazards to this lifestyle. But while the didinium is extremely talented at paramecium, and also capable of hunting other organisms, it's actually pretty bad in some of its other conquests. When didinium try to eat rotifers, they're stymied by the relatively touch exterior. And other ciliates like stentors are too large and too touch and too active for the didinium to do much damage to.”

Journey to the Microcosmos- Didinium: The Paramecium Hunter