Sea cucumbers and their symbiotic microbiome have evolved to feed on seabed sediments

Abstract

Sea cucumbers, classified as Holothuroidea within the phylum Echinodermata, are large and abundant members in marine benthic communities 1 . Sea cucumbers greatly impact the health and integrity of the marine ecosystem through bioturbation, organic matter processing, nutrient recycling, seawater chemistry balancing, biodiversity supporting, energy transfer in food chains 1,2 , and provide significant protective benefits to coral reefs by reducing their diseases 3 . Most sea cucumbers are deposit feeders, acquiring nutrients through the consumption of bacteria, microalgae, decayed plants, and meiofauna, along with other organic detritus [4][5][6] . By ingesting and defecating a large amount of seabed sediment, sea cucumbers facilitate bacterial decomposition and reduce the organic load 4,7 . To date, the specific