how sponges rely on water moving through their bodies for respiration.

Marine sponges are found in every habitat in every ocean in the world, from shallow reefs to deep arctic seas, anchored to corals and boulders and soft sediments alike.They range in size from tiny – less than an inch across, to huge, up to six feet in height. They’ve been there for many millions of years, among the oldest members of the animal kingdom. Invariably, sponges are there wherever we dive. NOBODY DIVES ON THE REEF TO SEE SPONGES, but they ought to.

A strawberry vase sponge (Mycale laxissima), blood red and often found on walls, as here in Roatan, Honduras. And, if corals disappear, sponges may be the future of reefs. Sponges were among the earliest arrivals in the ocean.

But ocean sponges come in amazing shapes and colors, chug along with body features unique in the animal kingdom and perform important reef-related roles. It’s easy to dismiss them as just backdrop scenery to more exotic stuff on the reef. What are sponges? They’re animals, perhaps animals that stretch our conception of the term, but animals for sure.

How sponges rely on water moving through their bodies for respiration.