NEWS - Incredible footage shows a marine species, Bathyopsurus nybelini, feeding on something that sinks from the ocean’s surface. Researchers using the submersible Alvin found the isopod swimming 3.7 miles down using its paddle-like legs to catch an unexpected food source: Sargassum.
Researchers from Woods Hole Oceanographic Institution (WHOI), the University of Montana, SUNY Geneseo, Willamette University and the University of Rhode Island found the algae sinking, while the isopod waited and adapted specifically to find and feed on the sinking nutrient source.
The Sargassum lives on the surface for photosynthesis. The discovery of a deep-sea animal that relies on food that sinks from the waters miles above underscores the close relationship between the surface and the deep.
“It’s fascinating to see this beautiful animal actively interacting with sargassum, so deep in the ocean. This isopod is extremely rare; only a handful of specimens were collected during the groundbreaking Swedish Deep Sea Expedition in 1948,” said Johanna Weston of Woods Hole Oceanographic Institution.
The research team combined morphological analysis, CT scanning, DNA sequencing and microbiological studies to show that the species is physiologically and behaviorally adapted to use submerged resources. The integrative process of observation and analysis revealed important links in this marine food web.
"Deep-sea ecosystems seem like harsh environments, but the animals that live in these habitats are perfectly suited to the conditions. Animals in dark, high-pressure environments have evolved adaptations to feed on algae that grow in ecosystems exposed to sunlight," said Mackenzie Gerringer of the State University of New York at Geneseo.
B. nybelini has adapted a special swimming style. It moves upside down and backward with large paddles that allow it to scoop up sargassum from the seafloor. This distinctive movement may be an evolutionary strategy to avoid predation in shallow waters.
The animal also has a serrated mouth that is ideal for tearing apart tough algae, while gut bacteria help with digestion. Algae are difficult for many animals to digest because their cell walls are made of polysaccharides, strong, complex molecules. The gut microbiome has genes to break down these tough compounds.
"Life everywhere, even in the deepest ocean depths, is inextricably linked to the microorganisms around it," said Logan Peoples of the University of Montana at Polson.
Sargassum in the tropical Atlantic and Caribbean appears to have changed with a major explosion that created an impact ecological and economic importance to coastal communities in the region. Much remains to be understood about the abundance and uses of Sargassum in the deep sea. Algae have significant implications for carbon cycling and storage.
Original research
Peoples Logan M., Gerringer Mackenzie E., Weston Johanna N. J., León-Zayas Rosa, Sekarore Abisage, Sheehan Grace, Church Matthew J., Michel Anna P. M., Soule S. Adam and Shank Timothy M. (2024). A deep-sea isopod that consumes Sargassum sinking from the ocean’s surface. Proceedings of the Royal Society B: Biological Sciences, 29120240823, DOI:10.1098/rspb.2024.0823