Sea star with urchins and anemones

Sea Stars

Loan Ochre sea star on rock
Ochre sea stars feeding on mussels Ochre sea stars feeding on mussels Ochre sea stars feeding on mussels Ochre sea stars have different color variations Single Ochre sea star feeding on mussel Purple Ochre sea star near similar colored algae Ochre sea stars exposed at low tide

Ochre Sea Star ( Pisaster ochraceous )

This is the most common sea star in the tide pool environment. These sea stars appear in a variety of colors including orange, browns and purple. They live in the lower inter tidal zone and almost always found near mussel and barnacle beds. They may appear higher in the tidal zone wedged inside cracks and nooks where they can preserve moisture and stay cool. When the tide is high they will start moving around looking for food. It has been estimated that an adult Ochre sea star will eat about 80 mussels in a year. Adults are usually between 8-12 inches but larger specimens can be found.
Multicolored bat star in aquarium
Pink colored bat star Bat star exposed at low tide

Bat Star (Patiria miniata)

The Bat star is easily recognizable in that the arms are connected by a web. They also come in a variety of colors ranging from orange, red, purple and others. They are frequently molted and may have more than one color. Bat stars are omnivorous in that they will eat both plant and animals. They are fairly common in the lower inter tidal zone.

Brittle Star (Amphiodia occidentalis )

Brittle stars have five arms as other sea stars but the arms are much thinner and longer. They also can use these arms for movement whereas other sea stars rely on their tube feet for moving. This species of brittle star is usually a brownish to darker brown color and found under rocks in the lower tide zone.
Giant sea star in aquarium
Giant sea star Close up of Giant sea star arm Close up of Giant sea star eye spot ( red area on tip of arm )

Giant Sea Star (Pisaster giganteus )

The giant sea star ( aka Knobby Sea Star ) is typically brownish to darker brown with lots of short spines that are white with blue rings at the base. This sea star gets its name in that the spines are larger than most other sea stars. Knobby sea stars can grow up to two feet in diameter. They are rarely seen in the tide pools as they typically live much deeper and like to live near kelp forests. They feed on a variety of mollusks.
Pink sea star in aquarium
Pink sea star in aquarium

Pink Sea Star (Pisaster brevispinus)

The pink sea star ( aka short spine sea star ) is another larger sea star rarely seen in the tide pools. Larger specimens can reach 2 feet in diameter. They typically live in much deeper water and feed on clams and mollusks.
Description – Sea stars belong to a group of animals that call Echinoderms. This translates into spiny skin. Sea stars have hard outer skin with many short spines or bumps (ossicles) on the top part of the animal. Sea stars usually have 5 arms that radiate out from a central body. They have tube feet that are used to catch prey and move around. The coloration of sea stars varies between species as well as the body form. Sea stars are typically found in the lower tide pool region.

Feeding – Sea stars are carnivorous in that they feed on other animals. They can use their tube feet to attach to the shells of mussels and barnacles and pull the shells apart. Sea stars then invert their stomachs into the opened shell and digest the prey from within their own shells. Sea stars are incredibly strong and only the largest mussels and barnacles can withstand an attack.

Protection – Sea stars have a combination of physical and behavioral protection strategies. They have hard outer bodies the can withstand most attacks. They can cling to rocks and other substrate using their strong tube feed to withstand predation from sea gulls and sea otters.

Ecology – Sea stars are characterized by having hundreds of tube feet. These tube feet are used for locomotion and feeding. Some sea stars like the Ochre have small eye spots on the tips of their arms. These simple eyes can distinguish between light and dark and may be used to determine shady locations and time of days. Several sea stars have multiple stomachs that can be extended into their prey animals.

Ochre sea stars can live for over 20 years in the right conditions. The adults periodically release eggs and sperm into the ocean where fertilization takes place. The juvenile sea stars spend several weeks in the open ocean before settling on a rock or other substrate. The juveniles then transform into the adult form and begin to grow.
Posted in Animals.

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