AcanthostegaAcanthostega (meaning "spiny roof") is an extinct genus of stem-tetrapod, among the first vertebrate animals to have recognizable limbs. It appeared in the late Devonian period (Famennian age) about 365 million years ago, and was anatomically intermediate between lobe-finned fishes and those that were fully capable of coming onto land. The Acanthostega had eight digits on each hand (the number of digits on the feet is unclear) linked by webbing, it lacked wrists, and was generally poorly adapted for walking on land.
Fish stocksFish stocks are subpopulations of a particular species of fish, for which intrinsic parameters (growth, recruitment, mortality and fishing mortality) are traditionally regarded as the significant factors determining the stock's population dynamics, while extrinsic factors (immigration and emigration) are traditionally ignored. All species have geographic limits to their distribution, which are determined by their tolerance to environmental conditions, and their ability to compete successfully with other species.
JonahJonah or Jonas, son of Amittai, is a prophet in the Hebrew Bible from Gath-hepher of the northern kingdom of Israel in about the 8th century BCE. Jonah is the central figure of the Book of Jonah, which details his reluctance in delivering God's judgement on the city of Nineveh. Subsequently he returns to the divine mission after he is swallowed by a large sea creature and then released. In Judaism, the story of Jonah represents the teaching of teshuva, which is the ability to repent and be forgiven by God.
AquacultureAquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. lotus). Aquaculture involves cultivating freshwater, brackish water and saltwater populations under controlled or semi-natural conditions, and can be contrasted with commercial fishing, which is the harvesting of wild fish.
Countercurrent exchangeCountercurrent exchange is a mechanism occurring in nature and mimicked in industry and engineering, in which there is a crossover of some property, usually heat or some chemical, between two flowing bodies flowing in opposite directions to each other. The flowing bodies can be liquids, gases, or even solid powders, or any combination of those. For example, in a distillation column, the vapors bubble up through the downward flowing liquid while exchanging both heat and mass.
Alligator garThe alligator gar (Atractosteus spatula) is an euryhaline ray-finned fish in the clade Ginglymodi of the infraclass Holostei hoʊˈlɒstiai, being most closely related to the bowfins. It is the largest species in the gar family (Lepisosteidae), and is among the largest freshwater fish in North America. The fossil record traces its group's existence back to the Early Cretaceous over 100 million years ago.
Channel catfishThe channel catfish (Ictalurus punctatus) is North America's most numerous catfish species. It is the official fish of Kansas, Missouri, Nebraska, and Tennessee, and is informally referred to as a "channel cat". In the United States, they are the most fished catfish species with around 8 million anglers targeting them per year. They also have very few teeth and swallow food whole. The popularity of channel catfish for food has contributed to the rapid expansion of aquaculture of this species in the United States.
Swim bladderThe swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled organ that contributes to the ability of many bony fish (but not cartilaginous fish) to control their buoyancy, and thus to stay at their current water depth without having to expend energy in swimming. Also, the dorsal position of the swim bladder means the center of mass is below the center of volume, allowing it to act as a stabilizing agent. Additionally, the swim bladder functions as a resonating chamber, to produce or receive sound.
AgnathaAgnatha ('ægnəθə,_æg'neɪθə; ) is an infraphylum of jawless fish in the phylum Chordata, subphylum Vertebrata, consisting of both present (cyclostomes) and extinct (conodonts and ostracoderms) species. Among recent animals, cyclostomes are sister to all vertebrates with jaws, known as gnathostomes. Recent molecular data, both from rRNA and from mtDNA as well as embryological data, strongly supports the hypothesis that living agnathans, the cyclostomes, are monophyletic.
SalvelinusSalvelinus is a genus of salmonid fish often called char or charr; some species are called "trout". Salvelinus is a member of the subfamily Salmoninae within the family Salmonidae. The genus has a northern circumpolar distribution, and most of its members are typically cold-water fish that primarily inhabit fresh waters. Many species also migrate to the sea. Most char may be identified by light-cream, pink, or red spots over a darker body. Scales tend to be small, with 115–200 along the lateral line.
