Achoo! Sneezing isn't just for landlubbers. Researchers have determined that sea sponges, multicellular organisms that live on the ocean floor, "sneeze" mucus to clear waste from their feeding systems. This action not only helps the sponge it also provides food for other ocean animals.
Coral reef ecologist Niklas Kornder of the University of Amsterdam led the study published in the journal Current Biology on Wednesday. The paper took a deep dive into why sponges sneeze.
Sponges are filter feeders that pump water through their bodies to sift out organic matter. The water travels in through inflow channels and out through outflow channels. The researchers observed sponges in aquariums and filmed their behavior. Scientists had expected the sponges would get rid of waste through the outflow pores on their bodies but were surprised to find a different mechanism at work.
"The footage showed that with each sneeze the collected mucus is released and the sponge is left with a clean surface," Kornder said in a University of Amsterdam statement on Wednesday. "The timelapses also showed that the mucus was continuously streamed out of the inflow openings, not the outflow openings, and slowly transported along distinct paths towards central collection points on the surfaces of the sponges."
The paper described the paths of flow as "mucus highways," which would be a terrible band name. The sneeze-like events happened every three to eight hours.
The researchers shared time-lapse videos of sponges sneezing. The close-up views look like alien worlds in upheaval.
One video shows a Chelonaplysilla sponge, which is a dark blue/purple color. Another video shows a reddish Aplysina archeri, which can be found in the Caribbean.
The sponge sneezes are a valuable source of food for other ocean dwellers. The team observed marine animals, including fish, snacking on the mucus expelled by sponges. The researchers want to learn more about the underlying mechanisms for sponge sneezing and also plan to look for the behavior in more species of the animals.
Humans can be grateful that our sneezes tend to be short-lived. "A sponge sneeze is not exactly the same as a human sneeze, because such a sneeze lasts around half an hour," Kornder said. "But they are indeed comparable, because for both sponges and humans, sneezing is a mechanism to get rid of waste."