Knowra Sunflower sea star Sunflower sea star The sunflower sea star is a large sea star native to the northeastern Pacific, known for its many arms and unusually rapid movement. Its populations have declined sharply since sea star wasting disease emerged.
Sea star locomotion : Sea stars move using hydraulic tube feet operated by a water vascular system. Hundreds of tube feet let this many-armed sea star travel faster than most sea stars.
Trophic cascade : A chain of ecological effects caused when changes in one trophic level alter others. Losing a major urchin predator can release its prey and alter kelp-forest communities.
Pycnopodia helianthoides : The scientific name of the sunflower sea star, the sole living species in its genus. This binomial identifies the species tracked in population surveys and conservation assessments.
Ochre sea star : A common northeastern Pacific sea star, usually with five arms, also known as the purple sea star. It experienced wasting-disease mortality too, but differs sharply from the sunflower sea star in size and arm count.
Water vascular system : A fluid-filled hydraulic network in echinoderms that powers tube feet and other functions. This hydraulic network drives the tube feet used in the sunflower sea star’s rapid movement.
Kelp forest : A coastal marine ecosystem dominated by large brown algae called kelp. Sunflower sea stars are predators in kelp forests, where their decline can affect urchin pressure.
Northeastern Pacific : The Pacific Ocean region bordering western North America from Alaska toward Baja California. This broad coastal region contains the sunflower sea star’s native range.
Sea otter : A marine mammal that feeds on invertebrates, including sea urchins, along North Pacific coasts. Sea otters provide another source of urchin predation in ecosystems affected by sunflower sea star loss.
Sea star feeding : Sea stars capture and consume prey using tube feet, arms, and, in many species, an everted stomach. Its mobile arms and tube feet help it seize and open prey such as sea urchins.
Purple sea urchin : A small, spiny sea urchin common on the northeastern Pacific coast. It is a key prey item whose abundance can rise when sunflower sea stars disappear.
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