Elephant's Hide Sponge

Pachymatisma johnstonia

The Elephant's Hide Sponge, Pachymatisma johnstonia, is a distinctive sponge found along the north-eastern Atlantic coasts, including the UK, Spain, and France. It is notable for its grey encrusting appearance with large, prominent oscula and a pale yellow interior. The sponge's size and form are influenced by its exposure to waves. In areas with heavy wave action, it tends to be smaller and thinner, while in more sheltered locations, it can grow to over 50 cm across and 15 cm thick. This sponge is typically found in temperate waters, thriving in depths shallower than 40 meters, with the majority of occurrences at depths less than 30 meters. As a sessile organism, it remains attached to substrates in its environment. Like other members of the class Demospongiae, the Elephant's Hide Sponge is hermaphroditic. It reproduces through a life cycle that begins with a free-swimming parenchymella larva, which eventually settles on a substrate to grow into a young sponge. Divers encountering this sponge will find it harmless, and it poses no threat to humans. Its conservation status has not been evaluated by the IUCN, and there are no specific threats or uses noted for this species. Observing this sponge can provide insight into the diverse sponge communities present in temperate reef ecosystems.