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An echinoderm is any member of the phylum Echinodermata. The adults are recognisable by their radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the sea lilies or "stone lilies". Adult echinoderms are found on the sea bed at every ocean depth, from the intertidal zone to the abyssal zone. The phylum contains about 7,000 living species, making it the second-largest grouping of deuterostomes, after the chordates. Echinoderms are the largest entirely marine phylum. The first definitive echinoderms appeared near the start of the Cambrian.
Steller's sea cow is an extinct sirenian described by Georg Wilhelm Steller in 1741. At that time, it was found only around the Commander Islands in the Bering Sea between Alaska and Russia; its range extended across the North Pacific during the Pleistocene epoch, and likely contracted to such an extreme degree due to the glacial cycle. It is possible indigenous populations interacted with the animal before Europeans. Steller first encountered it on Vitus Bering's Great Northern Expedition when the crew became shipwrecked on Bering Island. Much of what is known about its behavior comes from Steller's observations on the island, documented in his posthumous publication On the Beasts of the Sea. Within 27 years of its discovery by Europeans, the slow-moving and easily-caught mammal was hunted into extinction for its meat, fat, and hide.
Sea urchins are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin are distributed on the seabeds of every ocean and inhabit every depth zone from the intertidal seashore down to 5,000 meters. The spherical, hard shells (tests) of sea urchins are round and covered in spines. Most urchin spines range in length from 3 to 10 cm, with outliers such as the black sea urchin possessing spines as long as 30 cm (12 in). Sea urchins move slowly, crawling with tube feet, and also propel themselves with their spines. Although algae are the primary diet, sea urchins also eat slow-moving (sessile) animals. Predators that eat sea urchins include a wide variety of fish, starfish, crabs, marine mammals, and humans.
Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea. Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or basket stars. Starfish are also known as asteroids due to being in the class Asteroidea. About 1,900 species of starfish live on the seabed in all the world's oceans, from warm, tropical zones to frigid, polar regions. They are found from the intertidal zone down to abyssal depths, at 6,000 m (20,000 ft) below the surface.
A keystone species is a species that has a disproportionately large effect on its natural environment relative to its abundance, a concept introduced in 1969 by the zoologist Robert T. Paine. Keystone species play a critical role in maintaining the structure of an ecological community, affecting many other organisms in an ecosystem and helping to determine the types and numbers of various other species in the community. Without keystone species, the ecosystem would be dramatically different or cease to exist altogether. Some keystone species, such as the wolf, are also apex predators.
The sea otter is a marine mammal native to the coasts of the northern and eastern North Pacific Ocean. Adult sea otters typically weigh between 14 and 45 kg, making them the heaviest members of the weasel family, but among the smallest marine mammals. Unlike most marine mammals, the sea otter's primary form of insulation is an exceptionally thick coat of fur, the densest in the animal kingdom. Although it can walk on land, the sea otter is capable of living exclusively in the ocean.
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 Earth. Although algal kelp forest combined with coral reefs only cover 0.1% of Earth's total surface, they account for 0.9% of global primary productivity. Kelp forests occur worldwide throughout temperate and polar coastal oceans. In 2007, kelp forests were also discovered in tropical waters near Ecuador.
Nereocystis is a monotypic genus of subtidal kelp containing the species Nereocystis luetkeana. Some English names include edible kelp, bull kelp, bullwhip kelp, ribbon kelp, bladder wrack, and variations of these names. Due to the English name, bull kelp can be confused with southern bull kelps, which are found in the Southern Hemisphere. Nereocystis luetkeana forms thick beds on subtidal rocks, and is an important part of kelp forests.
Coralline algae are red algae in the order Corallinales. They are characterized by a thallus that is hard because of calcareous deposits contained within the cell walls. The colors of these algae are most typically pink, or some other shade of red, but some species can be purple, yellow, blue, white, or gray-green. Coralline algae play an important role in the ecology of coral reefs. Sea urchins, parrot fish, and limpets and chitons feed on coralline algae. In the temperate Mediterranean Sea, coralline algae are the main builders of a typical algal reef, the Coralligène ("coralligenous"). Many are typically encrusting and rock-like, found in marine waters all over the world. Only one species lives in freshwater. Unattached specimens may form relatively smooth compact balls to warty or fruticose thalli.
The red sea urchin is a sea urchin found in the northeastern Pacific Ocean from Alaska to Baja California. It lives in shallow waters from the low-tide line to greater than 280 m (920 ft) deep, and is typically found on rocky shores sheltered from extreme wave action in areas where kelp is available.
An urchin barren is commonly defined as an urchin-dominated area with little or no kelp. Urchin grazing pressure on kelp is a direct and observable cause a "barren" area. However, determining what causes these increased pressures is a complex problem and remains a matter of debate among scientists. Loss of "top" predators, particularly historic hunting sea otters, has often been cited as a cause of these barrens, particularly in California and along the Eastern Pacific. However, scientists continue to debate the relative importance of different controlling factors of these ecosystems. Some theories have emphasized the "top-down" pressures by predators, including other urchin predators exerting at different life stages. Others have emphasized "bottom-up" factors, including abiotic environmental variables affecting urchin recruitment and the abundance and resiliency of kelp. Today, many scientists would acknowledge there is a mix of top-down and bottom-up factors that affect when, how, and where these ecosystems shift between a kelp bed and an urchin barrens.
Kina is a sea urchin endemic to New Zealand. This echinoderm belongs to the family Echinometridae and it can reach a maximum diameter of 16–17 cm.
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 1 m (3.3 ft). Adult sunflower sea stars usually have 16 to 24 limbs. They vary in color.
Loxechinus albus is an echinoderm of the family Parechinidae, native to coastal southern South America, ranging from Ecuador, along the entire coasts of Peru and Chile, to Argentina, as well as the Falkland Islands. It is the only species in the genus Loxechinus. It is known as the Chilean sea urchin or red sea urchin, but the latter name is typically used for the North Pacific Mesocentrotus franciscanus and it is not the only species of sea urchin in Chile. L. albus is found on rocky reefs and shores in the intertidal and subtidal zones to a depth of 340 m (1,120 ft).
Aquaculture of giant kelp, Macrocystis pyrifera, is the cultivation of kelp for uses such as food, dietary supplements or potash. Giant kelp contains iodine, potassium, other minerals vitamins and carbohydrates.
Pugettia gracilis, commonly known as the graceful kelp crab, is a species of small crab in the family Epialtidae. It lives among forests of kelp on the Pacific coast of North America.
The sea otter, Enhydra lutris, is a member of the Mustelidae that is fully aquatic. Sea otters are the smallest of the marine mammals, but they are also the most dexterous. Sea otters are known for their ability to use stones as anvils or hammers to facilitate access to hard-to-reach prey items. Furthermore, out of the thirteen currently known species of otters, at least 10 demonstrate stone handling behaviour, suggesting that otters may have a genetic predisposition to manipulate stones. Tool use behavior is more associated with geographic location than sub-species. Most behavioral research has been conducted on Enhydra lutris nereis, the Californian otter, and some has been conducted on Enhydra lutris kenyoni, the Alaska sea otter. Sea otters frequently use rocks as anvils to crack open prey, and they are also observed to rip open prey with their forepaws. While lying on their backs, otters will rip apart coral algae to find food among the debris. The frequency of tool use varies greatly between geographic regions and individual otters. Regardless of the frequency, the use of tools is present in the behavioral repertoire of sea otters and is performed when most appropriate to the situation.
The Great Southern Reef is a system of interconnected reefs that spans the southern coast of continental Australia and Tasmania and extends as far north as Brisbane to the east and Kalbarri to the west. It covers 71,000 km2 (27,000 sq mi) of ocean and straddles five states, running along the coast for 8,000 km (5,000 mi).
Tetrapygus is a genus of sea urchins in the family Arbaciidae. It is a monotypic genus and the only species is Tetrapygus niger which was first described by the Chilean naturalist Juan Ignacio Molina in 1782. It is found in the southeastern Pacific Ocean on the coasts of South America.
Ian Hewson is an Australian American biological oceanographer and marine ecologist who is a professor of microbiology at Cornell University. He leads the Cornell Marine Mass Mortality Laboratory, where he studies the drives of marine mass mortalities. He is leader of diversity, equity, and inclusion for the Department of Microbiology.
References
- ↑ "Brenda Konar | College of Fisheries and Ocean Sciences". uaf.edu. Retrieved 2022-07-19.
- ↑ Konar, Brenda (1991). Ecological studies of Geniculate coralline algae in Stillwater Cove, Carmel Bay, CA, with emphasis on Bossiella californica ssp. schmittii (Manza) Johans (Thesis). OCLC 26613414.
- ↑ Council, National Research; Board, Polar Research; Board, Ocean Studies; Board, Committee on a Science Plan for the North Pacific Research (2005-02-22). Final Comments on the Science Plan for the North Pacific Research Board. National Academies Press. ISBN 978-0-309-18207-2.
- ↑ Konar, Brenda (1998). Mechanisms that structure and maintain marine benthic communities at the Semichi Islands, Alaska. OCLC 777420553.
- ↑ "Konar Named Alaska NSF EPSCoR Lead". Alaska Business Magazine. 2021-06-03. Retrieved 2022-07-19.
- ↑ Pierre-Louis, Kendra (2019-01-30). "Scientists Single Out a Suspect in Starfish Carnage: Warming Oceans". The New York Times. ISSN 0362-4331 . Retrieved 2022-07-19.
- ↑ "Refuge Notebook: The fall of sea stars". Peninsula Clarion. 2021-03-02. Retrieved 2022-07-19.
- ↑ Bolton, Aaron; Homer, KBBI- (2017-08-15). "Can sea stars make a comeback in Kachemak Bay?". Alaska Public Media. Retrieved 2022-07-19.
- ↑ Ryan, John; Unalaska, KUCB- (2015-09-22). "Starfish losing arms to disease". Alaska Public Media. Retrieved 2022-07-19.
- ↑ Ricky (2014-08-06). "Wasting away — Unknown disease affecting sea stars along West Coast". The Mouth of The Kenai. Retrieved 2022-07-19.
- ↑ Cone, Marla (2007-12-01). Silent Snow: The Slow Poisoning of the Arctic. Open Road + Grove/Atlantic. ISBN 978-1-55584-769-2.
- ↑ "Without Otter Predation, Sea Urchins Decimate Aleutian Reefs". KUCB. 2020-10-03. Retrieved 2022-07-19.
- ↑ "Loss of sea otters accelerating the effects of climate change". ScienceDaily. Retrieved 2022-07-19.
- ↑ "Sea otters help lower carbon dioxide levels". The Johns Hopkins News-Letter. Retrieved 2022-07-19.
- ↑ "Combination of Climate Change and Predator Loss is Affecting Alaskan Reefs". AZoCleantech.com. 2020-09-11. Retrieved 2022-07-19.
- ↑ "How sea otters can reduce CO2 in the atmosphere: Appetite for sea urchins allows kelp to thrive". ScienceDaily. Retrieved 2022-07-19.
- ↑ "SitNews - UAF scientists discover new marine habitat in Alaska". www.sitnews.us. Retrieved 2022-07-19.
- ↑ Riosmena-Rodríguez, Rafael; Nelson, Wendy; Aguirre, Julio (2016-10-07). Rhodolith/Maërl Beds: A Global Perspective. Springer. ISBN 978-3-319-29315-8.