Although they lack nervous systems and muscles, recent observations have shown that sponges can contract slowly in order to expel sand and debris from the openings through which they feed. And it turns out that this “mucus” would be an important food source for other marine organisms.
Underwater sneezes
Can last up to 50 minutes, sneezing sponges involve contractions that will propel unwanted materials and substances in the form of long, sticky filaments of mucus. According to a new study published in the journal Current Biologysuch regular rejections of “ fresh biomass might explain why many fish and shellfish live near or on these fascinating marine organisms.
Sponges suck in water and dissolved nutrients (like sugars) through small holes called frostbites. Until now, these were thought to be trapped by their internal filtration system and expelled through larger openings, known as oscula. During a dive in the Caribbean Sea, Niklas Kornder from the University of Amsterdam was surprised to notice the presence of mucus in the ostioles of representatives of the species Aplysina archerswho had mysteriously disappeared an hour later.
In order to find out more, the scientist and his colleagues collected several specimens ofA. archers off the Caribbean island of Curaҫao and filmed them over a 24-hour period in their lab. Another representative of the species as well as a specimen of Chelonaplysilla have also been observed in the natural environment.
Viewing the various videos confirmed that this particle-laden substance emanated from the ostioles of these underwater creatures in the form of small bubbles, agglomerating to form long filaments probably made up of collagen ultimately released into the water at an average speed of 2 millionths of a meter per second when the sponge contracted.
Masses mainly made up of sediments
The analyzes carried out showed that the trapped sediment represented 81% of the mass of these clumps of mucus, which suggests that sneezing probably contributes to preventing their internal filtration system from clogging. The slime was also found to contain 45% more carbon and nitrogen than other types of natural waste found in the surrounding waters.
According to Kornder, observation of small crustaceans consuming it indicates that the remaining 19% potentially constitute an important food source for other marine organisms.
« This resource might contribute to the astonishing diversity that we observe on these very beautiful reefs with very complex ecosystems. “says the researcher. ” Although sponges lack both muscle and nerve cells, they do have primitive versions of these structures as well as a chemical signaling system that allows them to contract.. »
