Ochre sea star
The ochre sea star, also known as the purple sea star or ochre starfish, is a marine echinoderm found along the rocky shores of the Pacific Ocean, from Alaska to Mexico. Characterized by its five arms that extend from a central point, this radially symmetrical creature typically measures between four and ten inches (10 to 25 centimeters) across. Its body can be yellow, brown, or purple and is covered in tiny pincers, giving it a rough texture. The ochre sea star is a carnivore, primarily feeding on bivalve mollusks like sea mussels, utilizing its tube feet to locate and break into its prey.
During the spring, male and female ochre sea stars spawn by releasing eggs and sperm into the water, leading to the development of larvae that eventually settle on the seabed and mature into adults. Remarkably, the ochre sea star can regenerate lost arms, a useful adaptation when faced with predation. While the lifespan of the ochre sea star ranges from four to 20 years, its conservation status remains unevaluated. This fascinating creature plays an important ecological role in its habitat, contributing to the balance of marine life along the western North American coastline.
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Ochre sea star
The ochre sea star is a very close relative of the European starfish. The main difference between the two echinoderms, or spiny-skinned, creatures is in their geographical locations. Ochre sea stars live in the Pacific Ocean. They are also called purple sea stars and ochre starfish.
Kingdom: Animalia
Phylum: Echinodermata
Class: Asteroidea
Order: Forcipulatida
Family: Asteriidae
Genus: Pisaster
Species: Ochraceus
The ochre sea star may be found along the rocky beaches of western North America from Alaska to Mexico. This echinoderm, or spiny-skinned animal, is found in areas with strong waves and a great deal of tidal activity. It often inhabits tidal pools and mussel beds along these beaches.
The ochre sea star grows to be between four and 10 inches (10 to 25 centimeters) across. As a radially symmetrical animal, the ochre sea star generally has five arms which extend from its central axis, or middle point. A radially symmetrical animal is one whose body radiates, or extends, in a circle from a central point. If a curved line were to be drawn around the arms of the ochre sea star they would form a circle.
The body of the ochre sea star may be yellow, brown, or purple. It is rough to the touch because of many tiny pincers which cover the ochre sea star's body. In the center of its body the ochre sea star has a tiny star-shaped marking. The tips of this star-shaped marking point to each of the ochre sea star's five arms. The ochre sea star uses its arms to help in movement and feeding. On the bottom of each of the arms of the ochre sea star are rows of tiny, tube-like tentacles, or tube feet.
As a carnivore, or flesh-eater, the ochre sea star spends most of its time hunting for prey. The main source of its diet is bivalve mollusks, such as sea mussels. The ochre sea star finds its prey by the chemical signals which it picks up on its tube feet.
Although the sea mussel is able to tightly seal the two shells of its body, the ochre sea star is stronger. The ochre sea star breaks into the sea mussel by climbing onto the mussel and wrapping its body around the two shells. The ochre sea star sticks its tube feet to the shells of the mussel and rips open the creature. As it does this the ochre sea star inverts, or turns out, its stomach through its mouth opening and injects digestive fluids into the mussel. These digestive fluids work to dissolve the mussel's soft body tissue. When the mussel's body is a soft, soupy mixture it is sucked into the inverted stomach of the ochre sea star. The ochre sea star then releases the shells of the mussel, retracts its stomach, and slides onto the sand.
When an ochre sea star is attacked by a predator like a gull or sea otter it may lose one of its fragile, or easily-breakable, arms. Fortunately, the ochre sea star has the ability to grow a new arm to replace one that was lost. This process is known as regeneration.
Mating for the ochre sea star takes place in the spring when the water is warmer, usually from May through July. Male and female ochre sea stars begin the process of spawning by releasing their eggs and sperm into the water. After the eggs are fertilized by the sperm, they develop into small ochre sea star larvae. During this stage, the larvae float through the planktonic levels of the water, or the surface levels which are filled with tiny organisms known as plankton. Eventually, they develop into larger larvae with stronger arms and drop to the seabed. They make their way to the shores and develop into adult ochre sea star in the pools along the beach.
The life span of the ochre sea star is between four and 20 years. The conservation status of the ochre sea star has not been evaluated.
Bibliography
“Ochre Sea Star.” University of Puget Sound, 2024, www.pugetsound.edu/puget-sound-museum-natural-history/exhibits/marine-panel/ochre-sea-star. Accessed 6 May 2024.
“Ochre Sea Star.” Oregon Wild, 2019, oregonwild.org/wildlife/ochre-sea-star. Accessed 6 May 2024.