Sunflower seastar
| Sunflower seastar Pycnopodia helianthoides |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Echinodermata |
| Class: | Asteroidea |
| Order: | Forcipulatida |
| Family: | Asteriidae |
| Genus: | Pycnopodia |
| Species: | P. helianthoides |
| Binomial name | |
| Pycnopodia helianthoides Brandt, 1835 [1] |
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Pycnopodia helianthoides, commonly known as the sunflower seastar, is a large sea star found in the eastern Pacific. It is the largest sea star in the world, with a maximum armspan of 1 m (3.3 ft). Sunflower seastars usually have 16 to 24 limbs, their color can vary from yellow, orange, red, purple, or brown. They are predatory, feeding mostly on sea urchins, clams, snails, and other small invertebrates.
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[edit] Description
Sunflower seastars can grow to have an arm span of 1 m (3.3 ft) in diameter.[2] The color of the sunflower seastar ranges from bright orange, yellow and red to brown and sometimes to purple, with soft, velvet-textured bodies and 16 to 24 arms with powerful suckers.[2][3] Most sea star species have a mesh-like skeleton that protects their internal organs.[4]
[edit] Distribution and habitat
Sunflower seastars are common in the Pacific from Alaska to Southern California,[2] and are largest in Puget Sound, British Columbia and Alaska.[4] They generally inhabit low subtidal and intertidal areas rich in seaweed[5] or kelp.[6] They do not venture into high- and mid-tide areas because the body structure is fleshy and requires water to support it.[7]
[edit] Ecology
Sunflower seastars are quick, efficient hunters, moving at an astonishing speed of 1 m/s (3.3 ft/s) using 15,000 tube feet which lie on the undersides of the body.[2][3] They are commonly found around urchin barrens, as the sea urchin is a favorite food. They also eat clams, snails, abalone, sea cucumbers and other sea stars.[2] In Monterey Bay, California, they will feed upon dead or dying squid.[8] Although the sunflower seastar can greatly extend its mouth, for larger prey, the stomach can extend outside the mouth to digest prey, such as gastropods like abalone.[9]
Easily stressed by predators such as large fish and other sea stars, they can shed arms to escape, which will grow back within a few weeks. They are preyed upon by the king crab.[4]
[edit] Reproduction
Sunflower seastars can reproduce either asexually through fissiparity or sexually through broadcast spawning.[10] They also have separate sexes.[9] Sunflower seastars breed from May through June. In preparing to spawn, they arch up using a dozen or so arms to hoist its fleshy central mass free of the seafloor and release gametes into the water for external fertilization.[9] The microscopic sea star larvae float and feed near the surface for two to ten weeks. After the planktonic larval period, the larva settles to the bottom and transforms into a juvenile sunflower starfish.[4] Juvenile sunflower sea stars begin life with five arms, and grow the rest as they mature.[8] The life span of most sea stars is 3–5 years.
[edit] In popular culture
Their feeding behavior was filmed for the BBC in the 2006 nature documentary Planet Earth and again in 2009 for Life.
[edit] References
- ^ "Pycnopodia helianthoides". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=157274. Retrieved 9 April 2007.
- ^ a b c d e Sunflower seastar - NOAA
- ^ a b Telnack, Jennifer. Intertidal Marine Invertebrates of the South Puget Sound. NW Marine Life.[dead link]
- ^ a b c d Sunflowerstar. Scott Boyd's Emerald Sea Photography.
- ^ North Coast Intertidal Guide: Seastars & Urchins. North Coast Intertidal Guide. Humboldt State University. Arcata, CA.[dead link]
- ^ Sunflower Star. Channel Islands National Park. National Park Service.
- ^ Sunflower Star. North Island Explorer.
- ^ a b Monterey Bay Aquarium: Online Field Guide - Sunflower star. Monterey Bay Aquarium.
- ^ a b c Sea stars and relatives Edmonds Discovery Programs, City of Edmonds, Washington.
- ^ Aaron Shepard. "Pycnopodia helianthoides, The Sunflower Star". Evergreen State College.. http://academic.evergreen.edu/curricular/invertebratezoology/webpage/pycnopodiahelianthoides/pycnopodia.htm. Retrieved February 28, 2012.
[edit] External links
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Wikimedia Commons has media related to: Pycnopodia helianthoides |
