sunflower seastar
   HOME

TheInfoList



OR:

''Pycnopodia helianthoides'', commonly known as the sunflower sea star, is a large
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 ...
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 . Adult sunflower sea stars usually have 16 to 24 limbs; their color can vary widely. They are
predatory Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...
, feeding mostly on
sea urchin Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard shells (tests) of ...
s,
clam Clam is a common name for several kinds of bivalve molluscs. The word is often applied only to those that are edible and live as infauna, spending most of their lives halfway buried in the sand of the seafloor or riverbeds. Clams have two she ...
s,
snail A snail is, in loose terms, a shelled gastropod. The name is most often applied to land snails, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class Gastro ...
s, and other small invertebrates. Although the species had been widely distributed throughout the northeast Pacific, its population has rapidly declined since 2013. The sea star has been on IUCN list of endangered animals since 2021.


Description

Sunflower sea stars can grow to have an arm span of in diameter. They are the second-biggest sea star in the world, only second to the poorly known deep water '' Midgardia xandaros'', whose arm span is and its body is 2.6 cm (roughly 1 inch) wide, although ''P. helianthoides'' is the largest known echinoderm by mass. 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. 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.


Distribution and habitat

Sunflower sea stars were once common in the northeast Pacific from
Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S., ...
to
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 ...
, and were largest in
Puget Sound Puget Sound ( ) is a sound of the Pacific Northwest, an inlet of the Pacific Ocean, and part of the Salish Sea. It is located along the northwestern coast of the U.S. state of Washington. It is a complex estuarine system of interconnected ma ...
,
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, ...
,
northern California Northern California (colloquially known as NorCal) is a geographic and cultural region that generally comprises the northern portion of the U.S. state of California. Spanning the state's northernmost 48 counties, its main population centers incl ...
, and southern
Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S., ...
. Between 2013–2015, the species underwent a rapid population decline due to
sea star wasting disease Sea star wasting disease or starfish wasting syndrome is a disease of starfish and several other echinoderms that appears sporadically, causing mass mortality of those affected. There are approximately 40 species of sea stars that have been affe ...
, warmer water temperatures and abnormally high water temperatures caused by global
climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...
. The species disappeared from its habitats in the waters off the coast of
California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...
and
Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...
, and saw its population reduced by 99.2% in the waters near
Washington state Washington (), officially the State of Washington, is a state in the Pacific Northwest region of the Western United States. Named for George Washington—the first U.S. president—the state was formed from the western part of the Washington ...
. 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. As of 2020, the species has been declared critically endangered by the International Union for Conservation of Nature. There have been suggestions of the sea star wasting disease being caused by bacterial pathogens or parasites and being contagious, due to its tendency to spread to multiples locations. Sunflower sea stars generally inhabit low subtidal and intertidal areas rich in seaweed, kelp, sand, mud, shells, gravel, or rocky bottoms. They do not venture into high- and mid-tide areas because their body structure is heavy, and requires water to support it.


Diet

Sunflower sea stars are quick, efficient hunters, moving at a speed of using 15,000 tube feet which lie on the undersides of their bodies. They are commonly found around
urchin barrens An urchin barren is an area of the shallow part of the ocean where the population growth of sea urchins has gone unchecked, causing destructive grazing of kelp forests. Process Sea urchins eat kelp holdfasts. This can be caused by a lack of se ...
, as the sea urchin is a favorite food. They also eat clams, snails, abalone, sea cucumbers and other sea stars. In
Monterey Bay Monterey Bay is a bay of the Pacific Ocean located on the coast of the U.S. state of California, south of the San Francisco Bay Area and its major city at the south of the bay, San Jose. San Francisco itself is further north along the coast, by a ...
, California, they will feed on dead or dying
squid True squid are molluscs with an elongated soft body, large eyes, eight arms, and two tentacles in the superorder Decapodiformes, though many other molluscs within the broader Neocoleoidea are also called squid despite not strictly fitting t ...
. 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. 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 Abalone ( or ; via Spanish , from Rumsen ''aulón'') is a common name for any of a group of small to very large marine gastropod molluscs in the family (biology), family Haliotidae. Other common name In biology, a common name of a taxon o ...
. 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 King crabs are a taxon of decapod crustaceans chiefly found in cold seas. Because of their large size and the taste of their meat, many species are widely caught and sold as food, the most common being the red king crab (''Paralithodes camtscha ...
.


Reproduction

Sunflower sea stars can reproduce sexually through broadcast spawning. They also have separate sexes. 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. The microscopic sea star larvae float and feed near the surface for two to ten weeks. After the
planktonic Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucia ...
larval period, the larvae settle to the bottom and transform into juveniles. Juvenile sunflower sea stars begin life with five arms, and grow the rest as they mature. 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 The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...
first assessed that the sunflower sea star was critically endangered.
The Nature Conservancy The Nature Conservancy (TNC) is a global environmental organization headquartered in Arlington, Virginia. it works via affiliates or branches in 79 countries and territories, as well as across every state in the US. Founded in 1951, The Natu ...
and its partnered institutions, along with the
University of Washington The University of Washington (UW, simply Washington, or informally U-Dub) is a public research university in Seattle, Washington. Founded in 1861, Washington is one of the oldest universities on the West Coast; it was established in Seattle a ...
are working together to start the first captive breeding of sunflower sea stars 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. On August 18, 2021, the
Center for Biological Diversity The Center for Biological Diversity is a nonprofit membership organization known for its work protecting endangered species through legal action, scientific petitions, creative media and grassroots activism. It was founded in 1989 by Kieran Suckl ...
created a petition asking that the sunflower sea star be protected under the
Endangered Species Act The Endangered Species Act of 1973 (ESA or "The Act"; 16 U.S.C. § 1531 et seq.) is the primary law in the United States for protecting imperiled species. Designed to protect critically imperiled species from extinction as a "consequence of ec ...
.


Threats

Sunflower sea stars are one of the main predators of
sea urchin Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard shells (tests) of ...
s. By feeding on sea urchins, the sea stars control their population and help maintain the health of
kelp forest Kelp forests are underwater areas with a high density of kelp, which covers a large part of the world's coastlines. Smaller areas of anchored kelp are called kelp beds. They are recognized as one of the most productive and dynamic ecosystems on Ea ...
s. Due to the decrease in sea star population resulting from
sea star wasting disease Sea star wasting disease or starfish wasting syndrome is a disease of starfish and several other echinoderms that appears sporadically, causing mass mortality of those affected. There are approximately 40 species of sea stars that have been affe ...
, there is now an influx of sea urchins which pose a threat to biodiversity, particularly in kelp forests. The sea star wasting disease affects the sea star's whole body by spreading throughout the whole body. The limbs become affected and eventually fall off from the sea star ultimately ending in death from degradation. There is evidence to suggest the sea star wasting disease affecting sunflower sea stars is a Sea Star-associated Densovirus (SSaDV). The disease also creates behavioral changes and lesions within the species. 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.


References


External links

* * * {{DEFAULTSORT:Sunflower Sea Star Starfish described in 1835 Asteriidae