The invasive sponge Mycale grandis competes for space with local Hawaiian corals and sustains itself using amino acids produced by microbes living inside it, researchers reported July 17 in Microbial Ecology. The scientists analyzed concentrations of naturally occurring stable isotopes within the sponge to learn if it collected nutrients by catching food from the surrounding seawater, which would produce a distinct isotopic signature. Instead, they found that the sponge and the microbes it plays host to display identical isotopic patterns.
“The only way to produce the observed amino acid isotopic pattern, or fingerprint, if you will, is through the direct transfer of amino acids from their symbiotic bacteria,” says coauthor Joy Leilei Shih, a marine geochemist and conservationist at the University of Hawai‘i at Manoa, in a press release. The sponge still actively pumps water through itself, suggesting it may collect materials from the water to feed its symbiotic partner.
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