Sea Lemon

Doris pseudoargus

Sighting evidence at Cathedral Rock, St. Abbs Head

Photo: Leo · CC BY-NC

The sea lemon is one of the largest British nudibranchs and a regular sighting at Cathedral Rock from April through September, its warty yellow-green body blending remarkably well with coralline algae despite reaching 12 cm length. It feeds exclusively on sponges, particularly the breadcrumb sponge common on the arch walls. Egg spirals laid on rock faces are a reliable indicator of recent adult activity even when the animal itself has moved on.

Evidence at this site

5 records within 25 km

Confidence: medium

Last confirmed Mar 2026

Seasonality

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Feb

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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.