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Sunflower sea star

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Sunflower sea star
Scientific classification
Kingdom:
Animalia
Phylum:
Echinodermata
Class:
Asteroidea
Order:
Forcipulatida
Family:
Asteriidae
Genus:
Pycnopodia
Species:
P. helianthoides
Binomial name
Pycnopodia helianthoides
Brandt, 1835 [2]

Pycnopodia helianthoides, commonly known as the sunflower sea star, is a large sea star found in the northeast Pacific. The only species of its genus, it is among the largest sea stars in the world, with a maximum arm span of 1 m (3.3 ft). Adult sunflower sea stars usually have 16 to 24 limbs; their color can vary widely. They are predatory, feeding mostly on sea urchins, clams, snails, and other small invertebrates. Although the species had been widely distributed throughout the northeast Pacific, its population has rapidly declined since 2013.[3]

Description

A sunflower sea star with arms extended
Underside of a sunflower sea star

Sunflower sea stars can grow to have an arm span of 1 m (3.3 ft) in diameter. They are the second-biggest sea star in the world, only second to the poorly known deepwater Midgardia xandaros, whose arm span is 134 cm (53 in) and its body is 2.6 cm (roughly 1 inch) wide, although P. helianthoides is the largest known echinoderm by mass.[4] Growth of the Sea Star 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.[5]

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.[4][6] Most sea star species have a mesh-like skeleton that protects their internal organs.[7]

Distribution and habitat

Sunflower sea stars were once common in the northeast Pacific from Alaska to southern California,[4] and were largest in Puget Sound, British Columbia, northern California, and southern Alaska.[7] Between 2013–2015, the species underwent a rapid population decline due to sea star wasting disease, warmer water temperatures[8] and abnormally high water temperatures caused by global climate change.[3][9] 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.[3] 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.[10] As of 2020, the species has been declared critically endangered by the International Union for Conservation of Nature.[5]

Sunflower sea stars generally inhabit low subtidal and intertidal areas rich in seaweed,[11] kelp,[12] sand, mud, shells, gravel, or rocky bottoms.[13]They do not venture into high- and mid-tide areas because their body structure is heavy, and requires water to support it.[14][7]

Diet

Sunflower sea stars are quick, efficient hunters, moving at a speed of 1 m/min (3.3 ft/min) using 15,000 tube feet which lie on the undersides of their bodies.[4][6] 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.[4] In Monterey Bay, California, they will feed on dead or dying squid.[15] Sea star appetites and favorite food can depend on environmental factors in their habitats, such as climate, amount of prey in the area, and latitude.[16] Although the sunflower sea star can greatly extend its mouth, for larger prey, the stomach can extend outside the mouth to digest prey, such as gastropods like abalone.[17]

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.[7]

Reproduction

Sunflower sea stars can reproduce sexually through broadcast spawning.[18] They also have separate sexes.[17] Sunflower sea stars breed from May through June. In preparing to spawn, they arch up using a dozen or so arms to hoist their fleshy central mass free of the seafloor and release gametes into the water for external fertilization.[17] The microscopic sea star larvae float and feed near the surface for two to ten weeks. After the planktonic larval period, the larvae settle to the bottom and transform into juveniles.[7] Juvenile sunflower sea stars begin life with five arms, and grow the rest as they mature.[15] The lifespans of most sunflower sea stars is three to five years.

Conservation Efforts

Since 2013, sunflower sea star populations have been in a rapid decline due to disease and changes in climate affecting sea star habitats. Efforts have been made to spread awareness of this issue. In 2020, the IUCN first assessed that the sunflower sea star was critically endangered.[19] The Nature Conservancy and its partnered institutions, along with the University of Washington are working together to start the first captive breeding of Sunflower Sea Stars[20] in order to increase the population. Captive breeding efforts include seasonal reproduction of sea stars, the development of their larvae, and growth and feeding experiments for juvenile sea stars.[21] On August 18, 2021, the Center for Biological Diversity created a petition asking that the sunflower sea star be protected under the Endangered Species Act.[22]

Threats

Sunflower sea stars are one of the main predators of sea urchins.[23] By feeding on sea urchins, the sea stars control their population and help maintain the health of kelp forests.[24] Due to the decrease in sea star population resulting from sea star wasting disease, there is now an influx of sea urchins which pose a threat to biodiversity, particularly in kelp forests.[25] The Sea Star Wasting Disease affects the sea star's whole body by spreading throughout the whole body. The limbs (arms) become affected and eventually fall off from the sea star ultimately ending in death from degradation.[10] The disease also creates behavioral changes and lesions within the species.[26] This Disease is known to be more prevalent and harmful towards sea stars when the water is at a warmer temperature, which is seen in the habitats of the sun flower sea stars. The constant rate of the waters warming in California, Washington, and Oregon have coincided with the increased risk of the sea star wasting disease within the Pycnopodia helianthoides species in said areas. [10]

References

  1. ^ Gravem, S.A.; Heady, W. N.; Saccomanno, V.R.; Alvstad, K.F.; Gehman, A.L.M.; Frierson, T.N.; Hamilton, S.L. (2021) [2020]. "Pycnopodia helianthoides". IUCN Red List of Threatened Species. 2021 (amended assessment ed.): e.T178290276A197818455. Retrieved 18 July 2021.
  2. ^ "Pycnopodia helianthoides". Integrated Taxonomic Information System. Retrieved 9 April 2007.
  3. ^ a b c Yong, Ed (30 January 2019). "A starfish-killing disease is remaking the oceans". The Atlantic. Retrieved 30 January 2019.
  4. ^ a b c d e "Sunflower sea star". Fisheries. Species ID. NOAA. Retrieved 4 August 2021.{{cite web}}: CS1 maint: url-status (link)
  5. ^ a b Gravem, S.A.; Heady, W.N.; Saccomanno, V.R.; Alvstad, K.F.; Gehman, A.L.M.; Frierson, T.N.; Hamilton, S.L. (26 August 2020). "Pycnopodia helianthoides". IUCN Red List of Threatened Species (Report). doi:10.2305/iucn.uk.2020-3.rlts.t178290276a178341498.en. Retrieved 2 March 2021.
  6. ^ a b Telnack, Jennifer. Intertidal Marine Invertebrates of the South Puget Sound. NW Marine Life.
  7. ^ a b c d e Boyd, Scott. Sunflowerstar. Emerald Sea Photography (article & LD photos). Retrieved 31 March 2021.
  8. ^ Harvell, C. D.; Montecino-Latorre, D.; Caldwell, J. M.; Burt, J. M.; Bosley, K.; Keller, A.; Heron, S. F.; Salomon, A. K.; Lee, L.; Pontier, O.; Pattengill-Semmens, C. "Disease epidemic and a marine heat wave are associated with the continental-scale collapse of a pivotal predator (Pycnopodia helianthoides)". Science Advances. 5 (1): eaau7042. doi:10.1126/sciadv.aau7042. PMC 6353623. PMID 30729157.
  9. ^ Scigliano, Eric (23 January 2015). "Signs of hope, and a prime suspect, in sea star wasting disease". Washington Sea Grant. NOAA. Retrieved 4 August 2021.{{cite news}}: CS1 maint: url-status (link)
  10. ^ a b c Harvell, C.D.; Montecino-Latorre, D.; Caldwell, J.M.; Burt, J.M.; Bosley, K.; Keller, A.; et al. (30 January 2019). "Disease epidemic and a marine heat wave are associated with the continental-scale collapse of a pivotal predator (Pycnopodia helianthoides)". Science Advances. 5 (1): eaau7042. Bibcode:2019SciA....5.7042H. doi:10.1126/sciadv.aau7042. PMC 6353623. PMID 30729157.
  11. ^ "Seastars & Urchins". North Coast Intertidal Guide. Arcata, CA: Humboldt State University.[full citation needed]
  12. ^ "Sunflower Star". Channel Islands National Park. National Park Service.
  13. ^ "Pycnopodia helianthoides: Gravem, S.A., Heady, W. N., Saccomanno, V. R., Alvstad, K. F., Gehman, A. L. M., Frierson, T. N. & Hamilton, S.L." IUCN Red List of Threatened Species. 26 August 2020. Retrieved 10 November 2021.
  14. ^ "Sunflower Star". North Island Explorer.
  15. ^ a b "Sunflower star: Pycnopodia helianthoides". Field Guide (Online ed.). Monterey Bay Aquarium. Archived from the original on 24 July 2003. {{cite book}}: |website= ignored (help)
  16. ^ "Pycnopodia helianthoides: Gravem, S.A., Heady, W. N., Saccomanno, V. R., Alvstad, K. F., Gehman, A. L. M., Frierson, T. N. & Hamilton, S.L." IUCN Red List of Threatened Species. 26 August 2020. Retrieved 10 November 2021.
  17. ^ a b c Sea Stars and Relatives. Edmonds Discovery Programs. City of Edmonds, Washington.
  18. ^ Shepard, Aaron. "Pycnopodia helianthoides, the Sunflower Star". Invertebrate Zoology. Evergreen State College. Retrieved 28 February 2012.
  19. ^ Gravem, S.A.; Heady, W. N.; Saccomanno, V. R.; Alvstad, K. F.; Gehman, A. L. M.; Frierson, T. N.; Hamilton, S.L. (2021). "Pycnopodia helianthoides". IUCN Red List of Threatened Species. 2021: e.T178290276A197818455. doi:10.2305/IUCN.UK.2021-1.RLTS.T178290276A197818455.en. Retrieved 19 November 2021.
  20. ^ "Critically endangered sea star not recovering in the wild, scientists point to the need for restoration efforts". The Nature Conservancy. Retrieved 5 November 2021.
  21. ^ Hodin, Jason; Pearson-Lund, Alexi; Anteau, Fluer P.; Kitaeff, Pema; Cefalu, Shannon; Shannon, Troy; Yannou, Bernard; Leroy, Yann; Cluzel, François (2021). "Dataset for the manuscript: "Progress towards complete life-cycle culturing of the endangered sunflower star Pycnopodia helianthoides"". The Biological Bulletin. 241.
  22. ^ "Petition Seeks Protection for Sunflower Sea Star After 90% Population Decline". Center for Biological Diversity. Retrieved 5 November 2021.
  23. ^ Sean, Fleming (20 May 2021). "This sea star was almost killed off. Now scientists are breeding it to help fight climate change". World Economic Forum. Retrieved 1 January 2022.{{cite web}}: CS1 maint: url-status (link)
  24. ^ Simon Fraser University (13 August 2018). "Sea stars critical to kelp forest resilience". phys.org. Retrieved 24 November 2021.{{cite web}}: CS1 maint: url-status (link)
  25. ^ Harvell, C. D.; Montecino-Latorre, D.; Caldwell, J. M.; Burt, J. M.; Bosley, K.; Keller, A.; Heron, S. F.; Salomon, A. K.; Lee, L.; Pontier, O.; Pattengill-Semmens, C. "Disease epidemic and a marine heat wave are associated with the continental-scale collapse of a pivotal predator (Pycnopodia helianthoides)". Science Advances. 5 (1): eaau7042. doi:10.1126/sciadv.aau7042. PMC 6353623. PMID 30729157.
  26. ^ Hewson, Ian; Button, Jason B.; Gudenkauf, Brent M.; Miner, Benjamin; Newton, Alisa L.; Gaydos, Joseph K.; Wynne, Janna; Groves, Cathy L.; Hendler, Gordon; Murray, Michael; Fradkin, Steven (17 November 2014). "Densovirus associated with sea-star wasting disease and mass mortality". Proceedings of the National Academy of Sciences. 111 (48): 17278–17283. doi:10.1073/pnas.1416625111. ISSN 0027-8424. PMC 4260605.
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