Flesh Sponge

Overview

The Flesh Sponge (Oscarella lobularis) is a soft, gelatinous, and encrusting sponge known for its distinctively lobed, nodular appearance. Lacking both spicules and spongin fibers, it possesses a unique, velvety texture that sets it apart from many other sponge species.

Appearance

This sponge forms thick, fleshy colonies that typically feature an irregularly lobed surface covered in round, hollow nodules. Each nodule often displays a single, circular exhalant pore (osculum) at its peak, while smaller inhalant pores (ostia) are scattered across the sides. While its most characteristic coloration is blue, it is highly variable and can appear in shades of violet, purple, yellow, brown, green, or red, often with a lighter, cream-colored base.

Distribution & habitat

Primarily native to the Mediterranean Sea and the northeastern Atlantic, this species is commonly found on rocky substrates, including stones, boulders, and large algae. It thrives in a variety of environments, ranging from the intertidal zone and shallow coastal waters to deeper sublittoral habitats. It is frequently observed in sheltered areas, such as under rock overhangs, within caves, or among the rhizomes of seagrasses like Posidonia.

Biology & behavior

As a filter feeder, Oscarella lobularis draws water through its surface pores to extract nutrients. It is notable in biological research for its simple, well-defined epithelial structure and its ability to regenerate. Beyond sexual reproduction, it can reproduce asexually by releasing tissue fragments that detach and settle to form new colonies.