Information:  - Cod is the common name for the genus "Gadus" of demersal fishes, belonging to the family Gadidae. Cod is also used as part of the common name for a number of other fish species, and some species suggested to belong to genus "Gadus" are not called cod (the Alaska pollock).  - Attu is the westernmost and largest island in the Near Islands group of the Aleutian Islands of Alaska, and the westernmost point of land relative to Alaska, the United States, North America and the Americas. The island became uninhabited in 2010.  - The Scorpaeniformes are a diverse order of ray-finned fish, but have also been called the Scleroparei. It is one of the five largest orders of bony fishes by number of species with over 1,320.  - Sebastidae is a family of marine fish in the order Scorpaeniformes. Their common names include rockfishes, rock perches, ocean perches, sea perches, thornyheads, scorpionfishes, sea ruffes and rockcods. Despite the latter name, they are not closely related to the cods in the genus "Gadus", nor the rock cod, "Lotella rhacina".  - Natural gas is a naturally occurring hydrocarbon gas mixture consisting primarily of methane, but commonly including varying amounts of other higher alkanes, and sometimes a small percentage of carbon dioxide, nitrogen, hydrogen sulfide, or helium. It is formed when layers of decomposing plant and animal matter are exposed to intense heat and pressure under the surface of the Earth over millions of years. The energy that the plants originally obtained from the sun is stored in the form of chemical bonds in the gas.  - Alaska is a U.S. state located in the northwest extremity of North America. The Canadian administrative divisions of British Columbia and Yukon border the state to the east; its most extreme western part is Attu Island; it has a maritime border with Russia to the west across the Bering Strait. To the north are the Chukchi and Beaufort seasthe southern parts of the Arctic Ocean. The Pacific Ocean lies to the south and southwest. Alaska is the largest state in the United States by area, the 3rd least populous and the least densely populated of the 50 United States. Approximately half of Alaska's residents (the total estimated at 738,432 by the U.S. Census Bureau in 2015) live within the Anchorage metropolitan area. Alaska's economy is dominated by the fishing, natural gas, and oil industries, resources which it has in abundance. Military bases and tourism are also a significant part of the economy.  - Sebastes entomelas , the widow rockfish , is a type of rockfish ( Sebastidae ) that lives mainly off the coast of western North America from Alaska to Baja California . This fish is also commonly called widowfish and red snapper .  - The rock cod ("Lotella rhacina") is a temperate fish found off the coasts of southeastern Australia, Tasmania, the Great Australian Bight and northwards up the south western Australia coasts. They are also found around the coasts of New Zealand and California. They belong to the family Moridae and are not related to the true cods (genus "Gadus"). They are also known as beardie in Australia.  - Gadus is a genus of demersal fish in the family Gadidae, commonly known as cod, although there are additional cod species in other genera. The best known member of the genus is the Atlantic cod.    Given the information above, choose from the list below the object entity that exhibits the relation 'taxon rank' with the subject 'widow rockfish'.  Choices: - family  - form  - genus  - group  - order  - species
The answer to this question is:
species