English: Pollicipes polymerus (Sowerby, 1883) - gooseneck barnacles in Oregon, USA.

Crustaceans are a large group of arthropods that inhabit marine, marginal marine, freshwater, and terrestrial habitats. The group include crabs, lobsters, shrimp, crayfish, barnacles, ostracods, and other organisms. The oldest fossil crustaceans are in the Cambrian. Crustaceans experienced a significant radiation in the oceans during the Mesozoic Marine Revolution.

The organisms seen here are barnacles, which are sessile, benthic, filter-feeding, marine crustaceans - they are obligate hard substrate encrusters. They are particularly common in intertidal, rocky shore environments. Barnacles can tolerate subaerial exposure during low tides but have to be in water at least occasionally. When submerged, they extend their feathery limbs to filter feed. For many barnacles, the body is enclosed in a small, cinder cone volcano-shaped carapace composed of overlapping calcareous plates. Gooseneck barnacles are stalked and relatively large, with a vaguely bird head-shaped set of calcareous plates. Fossil barnacles first appear in Cambrian rocks.

These individuals are encrusting rocks of the Ginkgo Basalt, one of many lava flows in the Miocene-aged Columbia River Flood Basalt.

Classification: Animalia, Arthropoda, Crustacea, Maxillopoda, Cirripedia, Pollicipedomorpha, Pollicipedidae

Locality: low tide rocky shoreline on the southern side of Yaquina Head, coastal Oregon, USA

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Info. at: en.wikipedia.org/wiki/Pollicipes_polymerus and

en.wikipedia.org/wiki/Barnacle