Purple sea urchin

Echinoderm

Identification & Biology

• IdentificationA medium-sized sea urchin with a flattened, dome-shaped test and relatively short, dense, purple to dark violet spines. The most commercially and ecologically important sea urchin in the Mediterranean. Tube feet with suckers are visible between the spines.
• SizeTest diameter up to 7 cm (excluding spines).
• Social HabitGregarious. Found in dense populations on rocky reefs. Creates hemispherical depressions in soft limestone over time by rotating its spines and teeth. These cavities provide permanent shelter.
• HabitatRocky reefs and hard substrates in shallow, well-lit water. The dominant sea urchin on most Mediterranean rocky reefs.
• Depth0 to 80 m. Most abundant between 0 and 20 m.
• Feeds OnAlgae (primary food), seagrass, and encrusting organisms. One of the most important herbivorous grazers in the Mediterranean.
• DistributionEastern Atlantic from Ireland to Morocco and the Canary Islands, and throughout the Mediterranean Sea. Very common in Maltese waters.
• DescriptionParacentrotus lividus is the most ecologically significant sea urchin in the Mediterranean. It shapes entire reef communities through its grazing, and the balance between urchin populations and their fish predators determines whether a reef supports lush algal growth or bare urchin barrens. The gonads (roe) are considered a delicacy in many Mediterranean countries and are commercially harvested. Stepping on one barefoot is an unforgettable experience.