Giant Barrel Sponge

Photo: bdemol · CC BY-NC

Giant barrel sponges on the flanks of Bajo Minalta have grown to exceptional sizes — the largest specimens exceed 1.5 m in diameter — reflecting decades or centuries of undisturbed growth in a current-swept environment that delivers a continuous supply of planktonic food. They are often called the 'redwoods of the reef' and can live for more than 2,000 years, making each large individual a living archive of the reef's history. The sponges serve as shelter for hawkfish, gobies, and arrow crabs, and their filter-feeding removes bacteria and fine particulates from the water column at rates that measurably improve local water clarity.