Fish

Fish! is a text adventure game by Magnetic Scrolls released in 1988. The game was designed by John Molloy, Phil South and Peter Kemp with contributions by Rob Steggles.

A fish is an aquatic, anamniotic, gill-bearing vertebrate animal with a tough cranium to protect the brain, but lacking limbs with digits. Fish can be grouped into the more basal jawless fish and the more common jawed fish, the latter including all living cartilaginous and bony fish, as well as the extinct placoderms and acanthodians. Tetrapods are descended from fish, so in a break from the long tradition of grouping all fish into a single class (Pisces), modern phylogenetics views fish as a paraphyletic group that includes all vertebrates except tetrapods. To treat fish as a monophyletic group, one would have to classify tetrapods as a clade/subgroup of specialized fish, which would make "fish" and "vertebrates" synonyms. In English, the plural of "fish" is fish when referring to individuals and fishes when referring to species. Most fish are cold-blooded, their body temperature varying with the surrounding water, though some large, active swimmers like the white shark and tuna can maintain a higher core temperature. Many fish can communicate acoustically with each other, such as during courtship displays. The study of fish is known as ichthyology. There are over 33,000 extant species of fish, easily the largest group of vertebrates and more than all species of the other traditional classes, namely amphibians, reptiles, birds, and mammals, combined. Most fish belong to the class Actinopterygii, the ray-finned fishes, which accounts for approximately half of all living vertebrates. The earliest fish appeared during the Cambrian as small filter feeders; they continued to evolve through the Paleozoic, diversifying into many forms. The earliest fish with dedicated respiratory gills and paired fins, the ostracoderms, had heavy bony plates that served as protective exoskeletons against invertebrate predators. The first fish with jaws, the placoderms, appeared in the Silurian and greatly diversified during the Devonian, the "Age of Fishes". Bony fish, distinguished by the presence of swim bladders and later ossified endoskeletons, emerged as the dominant group of fish after the end-Devonian extinction wiped out the apex predators, the placoderms. Bony fish are further divided into lobe-finned and ray-finned fishes. About 96% of all living fish species today are teleosts- a crown group of ray-finned fish that can protrude their jaws. The tetrapods, a mostly terrestrial clade of vertebrates that have dominated the top trophic levels in both aquatic and terrestrial ecosystems since the Late Paleozoic, evolved from lobe-finned fish during the Carboniferous, developing air-breathing lungs homologous to swim bladders. Fish have been an important natural resource for humans since prehistoric times, especially as food. Commercial and subsistence fishers harvest fish in wild fisheries or farm them in ponds or breeding cages in the ocean. Fish are caught for recreation or raised by fishkeepers as ornaments for private and public exhibition in aquaria and garden ponds. Fish have had a role in human culture through the ages, serving as deities, religious symbols, and as the subjects of art, books and movies. File:Rhincodon typus fgbnms (cropped).jpg|Largest: whale shark File:Paedocypris progenetica 001.jpg|Smallest: e.g. Paedocypris progenetica Swimming performance varies from fish such as tuna, salmon, and jacks that can cover 10–20 body-lengths per second to species such as eels and rays that swim no more than 0.5 body-lengths per second. File:Salmo salar.jpg|Fastest: e.g. salmon, 10–20 body lengths/second File:Anguilla japonica 1856.jpg|Slowest: e.g. eel, 0.5 body lengths/second A typical fish is cold-blooded, has a streamlined body for rapid swimming, extracts oxygen from water using gills, has two sets of paired fins, one or two dorsal fins, an anal fin and a tail fin, jaws, skin covered with scales, and lays eggs. Each criterion has exceptions, creating a wide diversity in body shape and way of life. For example, some fast-swimming fish are warm-blooded, while some slow-swimming fish have abandoned streamlining in favour of other body shapes. File:Humpback anglerfish.png|Ambush predator: anglerfish File:Atl mackerel photo3 exp.jpg|Streamlined, somewhat warm-blooded: mackerel File:Hippocampus hippocampus (cropped).jpg|Tail not used for swimming: seahorse File:Phycodurus eques P2023146 (cropped).JPG|Camouflaged: leafy seadragon File:Eastern Cleaner Clingfish (cropped).jpg|No scales: clingfish File:Cyphotilapia frontosa mouthbrooding.jpg|Mouthbrooder: front cichlid with young in mouth File:Initial phase parrotfish feeding at Shaab Marsa Alam, Red Sea, Egypt -SCUBA (6336981391).jpg|A parrotfish feeding on algae on a coral reef File:Arothron hispidus is being cleaned by Hawaiian cleaner wrasses, Labroides phthirophagus 1.jpg|A cleaner fish removing parasites from its client, a pufferfish File:Barracuda with prey.jpg|A barracuda preying on a smaller fish File:1031 california sealion wright odfw (35281910502).jpg|Sea lion, a predatory mammal, eating a large salmonid File:Cormorant with fish (cropped).jpg|Cormorant with fish prey File:Lampanyctodes hectoris (Hector's lanternfish).svg|Anatomy of a typical fish (lanternfish shown): 1) gill cover 2) lateral line 3) dorsal fin 4) fat fin 5) caudal peduncle 6) caudal fin 7) anal fin 8) photophores 9) pelvic fins 10) pectoral fins Since body tissue is denser than water, fish must compensate for the difference or they will sink. Many bony fish have an internal organ called a swim bladder that allows them to adjust their buoyancy by increasing or decreasing the amount of gas it contains. The scales of fish provide protection from predators at the cost of adding stiffness and weight. Fish scales are often highly reflective; this silvering provides camouflage in the open ocean. Because the water all around is the same colour, reflecting an image of the water offers near-invisibility. File:Swim bladder.jpg|Gas-filled swim bladder of a rudd helps maintain neutral buoyancy. File:Fish scales.jpg|Silvered scales of a rohu provide protection and camouflage. brain, from above|alt=Diagram showing the pairs of olfactory, telencephalon, and optic lobes, followed by the cerebellum and the mylencephalon]] Fish have small brains relative to body size compared with other vertebrates, typically one-fifteenth the brain mass of a similarly sized bird or mammal. However, some fish have relatively large brains, notably mormyrids and sharks, which have brains about as large for their body weight as birds and marsupials. At the front of the brain are the olfactory lobes, a pair of structures that receive and process signals from the nostrils via the two olfactory nerves. Fish that hunt primarily by smell, such as hagfish and sharks, have very large olfactory lobes. Behind these is the telencephalon, which in fish deals mostly with olfaction. Together these structures form the forebrain. Connecting the forebrain to the midbrain is the diencephalon; it works with hormones and homeostasis. The pineal body is just above the diencephalon; it detects light, maintains circadian rhythms, and controls color changes. The midbrain contains the two optic lobes. These are very large in species that hunt by sight, such as rainbow trout and cichlids. The hindbrain controls swimming and balance. The single-lobed cerebellum is the biggest part of the brain; it is small in hagfish and lampreys, but very large in mormyrids, processing their electrical sense. The brain stem or myelencephalon controls some muscles and body organs, and governs respiration and osmoregulation. File:Matsya painting.jpg|Avatar of Vishnu as a Matsya, India File:Bartolomeo Passerotti - The Fishmonger's Shop - WGA17072.jpg|The Fishmonger's Shop, Bartolomeo Passerotti, 1580s File:Goldfish Matisse.jpg|Goldfish by Henri Matisse, 1912 Moyle, Peter B. (1993) Fish: An Enthusiast's Guide University of California Press. – good lay text. UCTV interview

Text derived from https://en.wikipedia.org/w/index.php?oldid=1376140556 under CC BY-SA 4.0; modifications have been made.