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Concept
Sunflower sea star
Summary
Pycnopodia helianthoides, commonly known as the sunflower sea star, is a large sea star found in the northeastern Pacific Ocean. The only species of its genus, it is among the largest sea stars in the world, with a maximum arm span of . Adult sunflower sea stars usually have 16 to 24 limbs. They vary in color.
They are predatory, feeding mostly on sea urchins, clams, sea snails, and other small invertebrates. Although the species was widely distributed throughout the northeast Pacific, its population rapidly declined from 2013. The sunflower sea star is classified as Critically Endangered on the IUCN Red List.
Sunflower sea stars can reach an arm span of . They are the second-biggest sea star in the world, second only to the little known deep water Midgardia xandaros, whose arm span is and whose body is 2.6 cm (roughly 1 inch) wide, although P. helianthoides is the largest known echinoderm by mass. Growth begins rapidly, but slows as the animal ages. Researchers estimate a growth rate of 8 cm (3.1 in)/year in the first several years of life, and a rate of 2.5 cm (0.98 in)/year later.
Their color ranges from bright orange, yellow-red to brown, and sometimes purple, with soft, velvet-textured bodies and 5–24 arms with powerful suckers. Most sea star species have a mesh-like skeleton that protects their internal organs.
Sunflower sea stars were once common in the northeast Pacific from Alaska to southern California, and were dominant in Puget Sound, British Columbia, northern California, and southern Alaska. Between 2013 and 2015, the population declined rapidly due to sea star wasting disease and warmer water temperatures caused by global climate change. The species disappeared from its habitats in the waters off the coast of California and Oregon, and saw its population reduced by 99.2% in the waters near Washington state. A team of ecologists using shallow water observations and deep offshore trawl surveys found declines of 80–100% from 2013 population levels across a 3,000 kilometer range.
Official source
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