Purple Sea Urchin

Paracentrotus lividus

Sighting evidence at Tsigrado Sea Cave, Milos

Photo: pavlaki1968 · CC BY

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

1 record within 25 km

Confidence: low

Last confirmed Jul 2025

Seasonality

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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.

Purple Sea Urchin

Evidence at this site

Seasonality

Also seen at other sites