Microbe Profiles: Suctorians
Learn the story of a microbe straight out of science fiction
Living invisibly to humans, there are tentacled predators that love a juicy paramecium. They are called Suctorians and they’re a part of protozoa, a taxonomic group that includes eukaryotic microbes with animal-like behaviors including predation.
Why the name?
Suctorians earned their truly SciFi name by sucking the cytoplasm out of their prey, often paralyzing them with their ray like tentacles.
Suctorians are ciliates, which means they have short hair-like structures called cilia all over their cell membrane. Cilia can help young Suctorians move through their environments. Adult Suctorians lose their cilia and retire to a relatively stationary life.
Feeding and Breeding
In nature, Suctorians eat other ciliates and also some microscopic animals like Rotifers.
In a paper published in 1952, J. A. Kitching from the Universtiy of Bristol gave a detailed description of how one genus of Suctorian feeds. After grasping its prey with its tentacles, the cilia of the Suctorian’s prey stop beating. In some cases, the body of the Suctorian becomes wrinkled as its surface increases in area and then becomes smooth again with the disintegration of the prey.
Suctoria is a subclass, containing multiple genera and species all with a fairly elementary baby-making process. Instead of binary fission, or more scandalous means, suctorians reproduce via external (or internal) budding. That means instead of simply dividing up the goods and splitting cells, the offspring is produced in a specific region of the parent and then buds off to live on its own.
Suctorian Tentacles 101
“…ingestion and transport in the suctorian tentacle”
“Microtubule Arms and The Feeding Tentacle of The Suctorian Ciliate…”
Numerous studies have been done on Suctorians, and they mostly focus on how they feed. Probably because they have tentacles for mouths. While frustratingly dense in information, many of those papers have got some pretty good stories to tell.
In decades following Kitching’s papers, scientists seemed to remain fascinated by Suctorian tentacles. In 1972, German scientists at the Zoological Institute of the University Tübingen examined the tentacles more closely and found that the actual feeding motion was more of a ‘grasp and pull’ than a suction. The tentacles were made up of outer and inner cylinders that were, in turn, made up of microtubules, filamentous structures responsible for movement inside eukaryotic cells.
While the outer cylinder was made of single microtubules, the inner shell was composed of microtubule ‘ribbons’ that could slide back and forth and were thought to be one of the main reasons for the unique feeding habits.
Further research at The University of St. Andrews, Scotland, in 1974 documented the bending, pivoting, splaying tendencies of the microtubules that form a bulb-like structure at the tip of the tentacle during feeding. Intertubular links that prevent splaying and could be put under tension when the tubules stretch, getting thinner and longer and sometimes changing shape.
Marine Life
Protozoa are common in marine environments, so it makes sense that you can find Suctorians in places that are damp or wet. They also have many interactions with macroscopic organisms, especially as epibionts, an organism that lives on the surface of another.
Universidad Complutense de Madrid gave a detailed review of Suctorian epibionts on crustaceans and found that there were 124 species that lived in relative harmony with things like crabs and lobsters.
They also are epibionts of some other arthropods called ‘halacarid mites’, tiny arachnids that have, since the Mesozoic period (252 to 66 million years ago), evolved into 56 species that dominate many freshwater habitats.
Suctorians don’t always play nice. In the Black Mouth Bass and other fish, they’ve been identified as parasites, leeching off their host’s resources. Regardless of how they get on with others, they seem to be isolated to wet, freshwater environments, although I couldn’t find anything to suggest they can’t also survive in salt water.
These are just some of the amazing living creatures that exist all around us at the microscopic level. In future installments, we’ll look at adventurous extremophiles, fancy eukaryotes, and useful bacteria to explore the amazing diversity of microbes!
Don’t take my word for it! View the full list of citations here.
If you like the Suctorians, you’ll probably like Conan the Bacterium. You can read about him here.
Hi! I’m flagellate. When I’m not swimming in agar, or writing about my favorite microbes, you can find me making up stories about the end of the world, and helping science get funded.
