The Halichondria panicea is a member of the class Demospongiae, it crumbles when handled. Panicea is a common sponge that encrusts hard substrata and seaweed on the shore and in shallow subtidal regions. Varying in color from dark green to light yellow, it is frequently found in shaded crevices or under overhangs. The morphology of Halichondria panicea can be highly variable. Most commonly found on the open coast, it can form a low crust with 'volcano' like exhalent openings. In wave sheltered areas, the species may grow to a massive form up to 20 cm thick, and in tidal rapids or sounds may be several meters across.

Halichondria panicea, commonly known as the breadcrumb sponge, is a species of marine demosponge belonging to the family Halichondriidae. This is an abundant sponge of coastal areas of the North Atlantic and the Mediterranean Sea ranging from the intertidal zone to a recorded depth of over 550m. It is very tolerant of a wide range of coastal habitats, including strong currents, high salinity and exposure to powerful wave action. Its only requirement is a rocky substrate which can include small cobbles.

 Halichondria panicea occurs in a very wide range of forms and can be difficult to identify. Some forms have a granular surface, which gives its common name, but sometimes the surface is smooth, even glassy. The surface is often marked with pores (osculae) which can extend into tubular "chimneys" in wave-sheltered habitats. The overall form is determined largely by the habitat: wave-exposed forms usually form thin widespread sheets but wave-sheltered forms often form massive encrustations up to 20 cm thick. The color is also variable. The "natural" color is cream or grey: this is usually found in specimens from relatively deep water. However at shallower depths, the sponge is usually green due to symbiotic algae which live close to the surface of the sponge. At intermediate depths the sponge tends to be green in summer, cream or grey in winter. One fairly reliable identifying feature is the smell: freshly collected specimens smell very strongly of seaweed.

 Halichondria panicea is a suspension feeder feeding mainly on phytoplankton. For such a common species, relatively little is known about its reproduction: It appears to be a hermaphrodite and oogenesis has been reported as occurring in a very narrow timeband within a single population although exceptions have been observed.

Author: Victoria H

Published: 03/2008