Natures wonders: barnacle cyanobacteria symbiosis (Introduction)

by David Turell , Monday, December 05, 2016, 18:43 (2908 days ago) @ David Turell

The two live together symbiotically on ocean-side rocks solving heat and moisture problems:

https://www.newscientist.com/article/2114955-weeping-rock-mystery-down-to-microbe-build...

"It’s a weeping rock. Sandstone blocks near the Lakes Entrance holiday resort on the coast of Victoria, south-east Australia, are covered with barnacles that look like they are spilling tears.

"How did those so called “Tears of the Virgin” get there?

It seems that the unique geological formation is a product of equally unique biology: the first known symbiotic relationship between crustaceans and bacteria.

***

"Working with Bill Newman from the Scripps Institution of Oceanography, California, he found that the barnacles (Chthamalus antennatus) are surrounded by dark-coloured microbes known as cyanobacteria, which feed on their nitrogen-rich waste. This results in the rounded eye shape from which the tears appear to fall.

"The cyanobacteria also excrete organic acids that dissolve carbonate, a major component of the sandstone (see below). The resulting burrows protect the barnacles from the fierce sun and material thrown up by waves.

"Excess acid dribbles down the surface of the rock and carves out grooves up to 17 centimetres long.

***

"The curious-looking formations are the first known example of a mutually beneficial relationship between a crustacean and bacterium, says Buckeridge. The barnacles provide food for the bacteria, while the bacteria dig out shelters up to 15 millimetres deep for the barnacles.

"Nevertheless, it is strange that the barnacles would team up with bacteria that erode the rock surface on which they live, Buckeridge says. “The really odd thing about this is how they manage to hang on.”

"The barnacles appear to cement themselves in place by sequestering residual non-carbonate rock towards the inner grooves of their shells, Buckeridge says.
The tears are submerged at high tide, so the barnacles are under the water for part of the day where they eat plankton. Barnacles are more commonly found lower in the intertidal zone but on these rocks they sit higher than usual. “This relationship with cyanobacteria gives them an opportunity to exploit a slightly higher zone, where there is less predation and competition,” he says.

"Perching on the rock surface above the water line is advantageous because the barnacles are less likely to fall prey to crabs and other marine organisms. However, the rock can reach 50 °C during summer, meaning the barnacles would succumb to dehydration if they couldn’t nestle into the burrows made by the cyanobacteria.
Similarly, without the barnacles, it would be harder for the cyanobacteria to find food in the hostile environment, says Buckeridge. “It’s a match made in heaven.'”

Comment: Logically not a match made by heaven. Cyanobacteria are in the ocean as are mollusks. They naturally fell together for mutual benefit.