Penares sphaera

Lore & Background

Penares sphaera is a deep sea demosponge that forms a thick encrusting growth on solid surfaces. Its body is very hard, almost stony, yet tears easily. The surface appears smooth but has a rough texture, and is dotted with white-ringed ostioles that may be more clustered in some areas. Oscules are abundant on the upper parts of the sponge.

The skeleton is composed of dichotriaenes—spicules that branch in pairs with short rays—which envelop the surface with their longest rays facing inward. Curved robust oxeas and curved microxeas are scattered in the choanosome, while the cortex is made of densely packed microxeas.

This species is found off the coast of Namibia and off the West, South and East Coasts of South Africa, at depths of 107 to 500 meters. It sometimes grows on other sponges, and molluscs may live within the sponge while other invertebrates may inhabit its surface.

Reader's Guide

Penares sphaera contributes to the understanding of deep sea sponge diversity off southern Africa. Its hard, stony texture and distinctive spicule arrangement—particularly the dichotriaenes with short rays that envelop the surface—help distinguish it from other demosponges. The presence of white-ringed ostioles and abundant oscules on the upper parts are characteristic field marks. Its ability to grow on solid surfaces and occasionally on other sponges, along with its role as a habitat for molluscs and other invertebrates, highlights its ecological function in deep sea benthic communities. The species' distribution across a wide depth range (107–500 m) and along multiple coasts of southern Africa suggests it is adapted to varied conditions. Its pale coloration and encrusting form are typical of many deep sea sponges, but the combination of spicule types and skeletal organization provides key taxonomic information. The species remains a subject of study for its structural adaptations and its interactions with associated fauna.

Did You Know?

• Penares sphaera is also known as the crater sponge.
• Its spicules include dichotriaenes that branch in pairs with short rays.
• This sponge is very hard and almost stony, but tears easily.
• Molluscs may be found living within the sponge.