Rock Pooling and Marine Life

Beach & Coast

The rocky shoreline of the Algarve is a living laboratory of marine biology, and rock pooling here rewards patient observation with sightings of creatures that range from the familiar to the genuinely surprising. The limestone and sandstone platforms that fringe many beaches are carved into channels, basins and shelves by wave action, creating pools that trap seawater at low tide and become temporary aquariums teeming with life.

The best rock pooling in the Algarve is found on the central and western coasts, where the rocky substrate is most extensive. Praia da Marinha, Praia do Carvoeiro, Praia dos Arrifes near Albufeira, and the platforms around Sagres and Burgau all offer excellent pools. The key to productive rock pooling is timing: visit at low tide, ideally during spring tides when the sea retreats furthest and exposes pools that are normally submerged. Tide tables for the Algarve are available online and in local tourist offices. Arriving an hour before low tide gives the best window of opportunity before the water starts to return.

The most commonly seen inhabitants of Algarve rock pools are hermit crabs, which scuttle about in borrowed shells and are endlessly entertaining for children. Shore crabs, both the green variety and the larger marbled rock crab, hide under stones and in crevices. Blennies, small elongated fish with blunt heads and expressive eyes, are abundant in pools of all sizes and are remarkably unafraid of human observers, often remaining still while being watched from close range.

Sea anemones are anchored to the rock in many pools, their tentacles waving gently in the water. The beadlet anemone, reddish-brown with a ring of blue beads around its base, is the most common species. Touching an anemone gently with a finger reveals the sticky sensation of its stinging cells, which are harmless to human skin but lethal to small prey items. Snakelocks anemones, larger and with long, bright green tentacles, are found in deeper, sunlit pools and are particularly photogenic.

Sea urchins are abundant on the lower shore, wedged into crevices and hollows where they graze on algae. The purple sea urchin is the species most frequently encountered, and its sharp spines are a hazard for barefoot waders. Wearing reef shoes or old trainers is strongly recommended when rock pooling in the Algarve. If a spine does penetrate the skin, soaking the affected area in hot water helps to soften the spine and reduce pain, but deeply embedded spines may require medical removal.

Starfish appear in lower pools near the water's edge, clinging to rock surfaces or draped over mussel beds. The common starfish and the spiny starfish are both present. In deeper pools, cushion stars, small and stiff-armed, can sometimes be found on the undersides of boulders. Turning rocks over to look for creatures is a time-honoured rock pooling technique, but it is important to replace rocks carefully in their original position afterwards, as the creatures living beneath them depend on the shelter.

Octopuses are the most exciting rock pool find, though they require a sharp eye. They are masters of camouflage, changing colour and texture to match their surroundings almost instantly. Look for them in pools with overhanging rock edges or deep crevices, and watch for a telltale pile of empty crab shells outside a hiding place, which indicates an octopus den. They are most active in early morning and late afternoon.

The intertidal zone of the Algarve also supports a variety of molluscs, including limpets, topshells, periwinkles and the striking painted topshell with its zigzag markings. Nudibranchs, or sea slugs, are occasionally found in lower pools and come in extraordinary colours, from electric blue to vivid orange. Photographing these tiny creatures requires patience and ideally a macro lens or a phone with a close-up attachment.

Rock pooling etiquette is simple but important. Do not remove creatures from their pools, as most will not survive in a bucket of stagnant water. Replace any rocks or seaweed that have been moved. Avoid stepping on living organisms wherever possible. And take care not to block drainage channels that allow water to flow between pools, as this can strand creatures in shrinking puddles.