Pachymatisma johnstonia

Elephant's-hide sponge

   Pachymatisma johnstonia is a massive sponge which may reach 40 cm in diameter and 10 cm in height. It has rounded margins and elongate lobes with a very smooth surface. Oscules are gathered in linear groups on the top of the lobes. Colour varies from greish white to dark purplish grey. It has a firm rubbery consistency.
It is attached to rocks, from swallow waters to depths up to 300 meters, in the English Channel, the Atlantic ocean from the North of the British Isles down to Spain and in the Mediterranean Sea.

Classification:

 Phylum Porifera, class Demospongiae, order Astrophorida, family Geodiidae, Pachymatisma johnstonia Bowerbank in Johnston, 1842.

Page glossary:

Oscule: Opening generally quite visible, through which sponges expel water they have filtered to extract food particles.

Authors:

Photograph:  © Wilfried Bay-Nouailhat. Published with author's kind permission.
Pachymatisma johnstonia, Iles Glénan, South-Brittany, West of France. Depth 15 meters.
Text:  Wilfried Bay-Nouailhat © 2006-2008.
Translation:  Anne Bay-Nouailhat © 2007-2008.