''Pisaster giganteus'', the giant sea star or giant spined star, is a species of

sea star Starfish or sea stars are Star polygon, star-shaped echinoderms belonging to the class (biology), class Asteroidea (). Common usage frequently finds these names being also applied to brittle star, ophiuroids, which are correctly referred to ...

that lives along the western coast of

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

from

Southern California Southern California (commonly shortened to SoCal) is a geographic and Cultural area, cultural region that generally comprises the southern portion of the U.S. state of California. It includes the Los Angeles metropolitan area, the second most po ...

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...

. It makes its home on rocky shores near the low tide mark. It preys on

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

s. It can grow as large as in diameter. Its color varies from brown to red or purple.

Reproduction and regeneration

Giant sea stars have small eggs, and their sperm contain spherical heads. Once their larvae are born, they are

bilaterally symmetrical Symmetry in biology refers to the symmetry observed in organisms, including plants, animals, fungi, and bacteria. External symmetry can be easily seen by just looking at an organism. For example, take the face of a human being which has a pla ...

. By the time they mature and reach adulthood they are centered on a set point with radial symmetry to their bodies. The gonads of the giant sea star grow in a winters time just in time for spawning season between the months of March and April.

Habitat

Giant sea stars are usually found around the protected coastlines with low tide. They can often be found attached to rocks, pier supports or in the sand.

Description

Giant sea stars have a dense body with wide arms. Its surface is either tan or brown, but on occasion the giant sea star can have a yellowish or grayish surface. They contain thick, blunt spines that are bluish in color with white, pink or purple tips that are swollen and surrounded by brown fuzz and

pedicellariae A pedicellaria (plural: pedicellariae) is a small wrench- or claw-shaped appendage with movable jaws, called valves, commonly found on echinoderms (phylum Echinodermata), particularly in sea stars (class Asteroidea) and sea urchins (class Echinoi ...

that have a plier like shape. These pedicellariae are used as a protective mechanism against predators. They have no distinct pattern. They range from from the tip of one arm to the other. They are usually found up to down in the water.

Predators and prey

The giant sea star only has a few predators.

Sea otter The sea otter (''Enhydra lutris'') is a marine mammal native to the coasts of the northern and eastern North Pacific Ocean. Adult sea otters typically weigh between , making them the heaviest members of the weasel family, but among the small ...

s and sea birds feed on giant sea stars, and their larvae are eaten by certain types of sea snails. They prey on several kinds of sea organisms including

barnacle A barnacle is a type of arthropod constituting the subclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in eros ...

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

s, and

limpet Limpets are a group of aquatic snails that exhibit a conical shell shape (patelliform) and a strong, muscular foot. Limpets are members of the class Gastropoda, but are polyphyletic, meaning the various groups called "limpets" descended indep ...

s. It eats its prey by extending its stomach so it can fit into tiny gaps, such as mussel shells.

Sources

Aquarius Aquarium Institute: Giant Sea StarLandenberger, Donald E. "Studies on Selective Feeding in the Pacific Starfish Pisaster in Southern California." ''Ecology, Vol. 49, No. 6 (Nov., 1968), pp. 1062-1075''. Online. March 3, 2008.Taxonomicon

References

{{Taxonbar, from=Q1641889 Asteriidae Animals described in 1857 Taxa named by William Stimpson