Giant Barrel Sponge

The giant barrel sponge (Xestospongia muta) is a huge, barrel-shaped sponge of Caribbean coral reefs that can be taller than a diver. It is sometimes called the redwood of the reef because some individuals may be extremely old.

🧬 Field Guide Specimen: Open Giant Barrel Sponge in the CRV Science Field Guide to log the specimen, see its place among the Metazoa lineages in the Cladogram Explorer, and test your recall in the Red List conservation game.

Growth measurements and models suggest that large barrel sponges could be more than a thousand years old, and some estimates exceed two thousand. The estimates are debated, but the animals do grow slowly and live a long time.

A single large sponge can pump thousands of liters of water a day through its body, removing bacteria and fine particles and recycling nutrients. Its tissues house dense communities of symbiotic microbes, including photosynthetic cyanobacteria.

Barrel sponges can lose their color in outbreaks of sponge orange band disease or bleaching events during heat stress. As corals decline on Caribbean reefs, sponges are becoming more dominant in some places. See Coral bleaching.

• Coral bleaching — stress on reef animals
• Staghorn Coral — a declining Caribbean reef builder