Pyramid Sea Star, Pharia pyramidata

Pyramid Sea Star, Pharia pyramidata. Star provided by the commercial fishermen of the greater Los Cabos area, Baja California Sur, December 2017. Pictured stars wingspan: 20 cm (7.9 inches).

Pyramid Sea Star, Pharia pyramidata. Underwater photographs taken in Zihuantanejo Bay, Guerrero, December 2019. Photographs courtesy of Ron Woheau, Zihuantanejo.

The Pyramid Sea Star, Pharia pyramidata (Grey, 1840) is a member of the Ophidiasteridae Family of Ophidiasterid Sea Stars, that is also known as the Yellow-spotted Sea Star in Mexico as estrella de mar piramide. This is the sole member of the Pharia Genus.

Pyramid Sea Stars have a small central disc and long arms that have rounded tips. Their aboral side has a smooth texture. They may be brown, gray, lavender or tan in color depending on their diet, with yellow to orangish spots on the discs arranged in rows on the arms. There are flattened spines running along the ambulacral grooves on the underside. Pyramid Sea Stars reach 30 cm (12 inches) in diameter.

The Pyramid Sea Star is found on and under rocks from the intertidal zone to depths up to 140 m (460 feet). They feed on algae, echinoderms, and other small invertebrates. This Sea Star and the Tan Sea Star, Phataria unifascialis, are sometimes parasitized by the Parasitic Cup Shell, Thyca callista. The cup shell attaches to the underside of the sea star’s arms. They suck fluids from their sea star host.

The Pyramid Sea Star is a resident of all Mexican waters of the Pacific Ocean.

Synonyms include Ophidiaster pyramidatus and Ophidiaster porosissimus.