scubaseason

Purple Sea Urchin

Paracentrotus lividus

Sighting evidence at Tsigrado Sea Cave, Milos

Dense aggregations of purple sea urchins carpet the cave walls and rocky ledges from 8 metres downward, grazing on coralline algae and controlling macroalgal growth. Their intense grazing can create bare rock patches — an important structuring force on this volcanic substrate. In the warm sediment patches near the thermal vents, urchin density drops markedly, suggesting thermal stress tolerance limits.

Evidence at this site

No confirmed records on file at this site

Purple Sea Urchin is listed as a curated species here based on historical reports.

How is this calculated?

Sighting evidence is compiled from iNaturalist observation records within a set proximity radius, filtered for quality-grade observations. “Last confirmed” is the date of the most recent research-grade record. Record count covers a rolling 24-month window. Confidence reflects record count, recency, and consistency of seasonal signal.

Also seen at other sites