Did you know sea sponges sneeze? Video shows the ‘mucus highways,’ researchers say

·2 min read
Screengrab from Kornder et al.'s video in Current Biology

A new study found evidence in timelapse videos that sea sponges — like humans — sneeze to get rid of mucus and other waste .

Sea sponges are underwater creatures with canal systems that suck water in, filter the nutritious substances and send water out, the researchers, led by Niklas Kornder, wrote in a study published Aug. 10 in the journal Current Biology.

Previously, scientists commonly assumed that sea sponges sent waste products out through the same larger pores that seawater exits through, the researchers explained. However, when they began to study this process of self-cleaning and waste removal in a tube sponge named Aplysina archeri, they found something unexpected.

“Sneezing,” the researchers wrote.

Timelapse footage shows sea sponges having “periodic surface contractions” that eject mucus into the water. Researchers recorded footage of two different types of sea sponges sneezing — a brilliant purple sponge from the Indo-Pacific called Chelonaplysilla, and Aplysina archeri, a vibrant red-pink sponge from the Caribbean.

The video shows the sponges contracting, almost beating rhythmically. Cloud-like clumps of white waste substances collect just above the sponges’ brightly-colored surface before suddenly disappearing.

As the video zooms in and slows down, the white clumps can be seen slowly collecting at specific points on the sponge.

Then another contraction — a sneeze — blows them away.

According to Kornder’s team, this sneezing process has three steps:

  1. The sponge expels particulate matter through the same pores that it uses to suck in seawater.

  2. These particles become “embedded in a stream of mucus” that moves along the surface and creates “translucent web-like patterns or ‘mucus highways’” that form “clumps” at mucus “highway ‘junctions.’”

  3. The sponge sneezes with “waves of coordinated contractions followed by relaxations.”

Then the process repeats itself, continuing to send mucus and waste away to prevent the sponge’s pore-filled surface from clogging.

“To this end, sponges may sneeze in a way analogous to human sneezing,” the researchers write. And unlike human sneezes, researchers said that nearby marine life will feed on sea sponges’ mucus and waste.

Many facets of sponge sneezes need more research, including the questions: How much waste do sponges sneeze out — and do all of them sneeze?

Kornder’s team said this is “notoriously difficult to quantify,” and they are not yet sure how widespread sneezing is among different types of sponges.

Still, the sea sponge “is a very sensitive and coordinated animal,” researcher Sally Leys told The Guardian, “despite not having all the characteristics that you’ve grown up to understand animals should have – fronts and backs, and eyes and tails and things like that. It’s constantly behaving in a way that we can relate to.”

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