This shaggy wanderer of the Northeast Atlantic, Aeolidiella glauca, is a master of camouflage and chemical warfare. Often overlooked due to its muted tones, this nudibranch is a rewarding find for any patient tide-pooler.
Identification
Reaching lengths of up to 45mm, *A. glauca* is characterized by its "shaggy" appearance. The body is typically a pale fawn, orange-brown, or greyish-pink. Its most striking feature is the dense covering of **cerata** (finger-like projections) which are tipped with distinct white spots. To distinguish it from its larger cousin, the Shag Rug Nudibranch (*Aeolidia papillosa*), look at the front of the body: in *A. glauca*, the cerata start further back, leaving a clearer "neck" area, and the body has a more translucent, delicate quality.
Habitat & Range
You’ll find this species throughout the Northeast Atlantic, from the Norwegian coast down to the Mediterranean. It favors the intertidal and shallow subtidal zones, particularly in sheltered bays with muddy or silty substrates. It is rarely found on exposed rocky headlands, preferring the calm of estuaries where its prey is abundant.
Behaviour
While somewhat nocturnal, *A. glauca* can be found during the day tucked into crevices or under stones near the low-water mark. It is a solitary hunter but may congregate during the breeding season. Look for its egg masses: exquisite, white, spiral ribbons typically coiled onto hard substrates or the base of seaweed.
Diet
This species is a specialist predator of sea anemones, specifically those in the genus *Sagartia* and the Daisy Anemone (*Cereus pedunculatus*). It forages by tracking the chemical scent of its prey through the water.
Fascinating Fact
*A. glauca* is a literal "stolen-weapon" specialist. When it eats an anemone, it digests the flesh but keeps the anemone’s stinging cells (**nematocysts**) intact. It transports these live weapons to the white tips of its cerata, using the anemone's own venom to sting any fish or crab that tries to eat it!