Rare detail discovered on new species hauled up from the ocean abyss
A newly discovered species of mollusc has a novel relationship with an anemone that protects it with long tenticles.
A new species has been discovered in the abyss at the bottom of the ocean, at a depth where the pressure is so great a diver’s lungs would collapse. The tiny shell was collected using a specialised net dropped 3,300 metres into the North Atlantic from the edge of a research vessel.
What’s rare about the newly described Fissidentalium aurae is its relationship with a small anemone that rides on its back. It’s the first time this “mutualistic” arrangement has been observed between a burrowing tusk shell and an anemone outside of the Pacific Ocean.
Researchers from the British Antarctic Survey (BAS) and the Senckenberg Society for Nature Research believe the arrangement protects the shell as the anemone can ward off predators using its tentacles. Anemones are normally stationary, and so they benefit by riding on the back of the mollusc to reach new food sources in what is a food-deficient environment.
Unfortunately for the mollusc that lives inside the shell, carrying a passenger has a major drawback. As the name suggests, the various species of burrowing tusk shell can normally burrow deep into the seafloor, but Fissidentalium aurae is unable to do so without harming the anemone.
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Little known about life deep in ocean
The new species was discovered during an expedition between north-eastern Canada and western Greenland. Several specimens were collected by the researchers while others were observed using seafloor imaging. The red and white individuals were an average of 1.1cm in diameter and 5.5cm long making the species larger than other closely related tusk shells.
The description of Fissidentalium aurae was published in the journal Springer Nature. Its lead author BAS biologist Katrin Linse said the discovery “serves as a reminder that we know so little about life in the deep, particularly the way that it adapts and how species pull together to benefit from each other’s presence.”
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