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Gymnarchus
The African knifefish, ''Gymnarchus niloticus'' – also called the ''aba aba'' – is an electric fish, living at the bottoms of rivers and lakes. It is the only species in the genus ''Gymnarchus'' and the family Gymnarchidae, within the order Osteoglossiformes. It is a long slender fish with no pelvic or anal fins, and a tail fin shaped like a rat's tail. It swims using its elongated dorsal fin, allowing it to keep its body straight while it moves. This in turn enables it to produce a steady but weak electric field, which it uses to locate its prey. It is large for a river fish; adults can reach 1.6 m (5.2 ft) in length and 19 kg (42 lb) in weight. In 1950, Hans Lissmann noticed that the fish could swim equally well forwards or backwards, clearly relying on a sense other than vision. He demonstrated that it could locate prey by electroreception, making it the first fish known to have this ability. The fish is considered good to eat in West Africa, wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Mormyroidea
The Mormyroidea (synonymy: Mormyriformes) are a superfamily (formerly an order) of fresh water fishes endemic to Africa that, together with the families ''Hiodontidae, Osteoglossidae, Pantodontidae'' and ''Notopteridae'', represents one of the main groups of living Osteoglossiformes. They stand out for their use of weak electric fields, which they use to orient themselves, reproduce, feed, and communicate. There is no consensus regarding its superior biological classification as some experts state that it belongs to the suborder '' Osteoglossoidei'', while others to the '' Notopteroidei''. In either case, the mormyriformes include the gymnarchids and mormyrids and represent the largest superfamily within the order ''Osteoglossiformes'' with about two hundred and thirty-three subordinate taxa that are distributed across various watersheds existing throughout tropical Africa south of the Sahara, including the Nile, Turkana, Gambia, and northern South Africa. These fish have a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Electrolocation
Electroreception and electrogenesis are the closely related biological abilities to perceive electrical stimuli and to generate electric fields. Both are used to locate prey; stronger electric discharges are used in a few groups of fishes, such as the electric eel, to stun prey. The capabilities are found almost exclusively in aquatic or amphibious animals, since water is a much better Conductor (material), conductor of electricity than air. In passive electrolocation, objects such as prey are detected by sensing the electric fields they create. In active electrolocation, fish generate a weak electric field and sense the different distortions of that field created by objects that conduct or resist electricity. Active electrolocation is practised by two groups of weakly electric fish, the order Gymnotiformes (knifefishes) and family Mormyridae (elephantfishes), and by the monotypic genus ''Gymnarchus'' (African knifefish). An electric fish generates an electric field using an Elect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Electric Fish
An electric fish is any fish that can Bioelectrogenesis, generate electric fields, whether to sense things around them, for defence, or to stun prey. Most fish able to produce shocks are also electroreceptive, meaning that they can sense electric fields. The only exception is the Uranoscopidae, stargazer family (Uranoscopidae). Electric fish, although a small minority of all fishes, include both oceanic and freshwater species, and both cartilaginous and bony fishes. Electric fish produce their electrical fields from an Electric organ (biology), electric organ. This is made up of electrocytes, modified muscle or nerve cells, specialized for producing strong electric fields, used to locate prey, for Anti-predator adaptation, defence against predators, and for Signalling theory, signalling, such as in courtship. Electric organ discharges are two types, pulse and wave, and vary both by species and by function. Electric fish have evolved many specialised behaviours. The predatory Cla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Hans Lissmann (zoologist)
Hans Werner Lissmann Fellow of the Royal Society, FRS (30 April 1909 – 21 April 1995) was a Great Britain, British zoologist of Ukraine, Ukrainian provenance, specialising in animal behaviour. He was elected a Fellow of the Royal Society in 1954, following breakthrough research with his assistant Kenneth E. Machin identifying the Passive electrolocation in fish, electric field generated by the Gymnarchus, African knifefish (''Gymnarchus''), and the uses which the fish makes of it. He was Reader, Department of Zoology, University of Cambridge, 1966–1977, then Reader Emeritus, and Director, Sub-Department of Animal Behaviour, 1969–1977. Life Early years Hans Werner Lissmann was born into a wealthy German family in Mykolaiv, Ukraine, which was then part of Russian Empire, Russia. As members of the Black Sea German, ethnic German minority the family fell under suspicion when First World War, war broke out in 1914. Lissmann and his elder brother were sent into "internal exil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Electric Organ (biology)
An Torpediniformes.html" ;"title="electric ray (Torpediniformes">electric ray (Torpediniformes) showing location of paired electric organs in the head, and electrocytes stacked within it In biology, the electric organ is an organ (biology), organ that an electric fish uses to create an electric field. Electric organs are derived from modified muscle or in some cases nerve tissue, called electrocytes, and have evolved at least six times among the Elasmobranchii, elasmobranchs and teleosts. These fish use their electric discharges for navigation, communication, mating, defence, and in strongly electric fish also for the incapacitation of prey. The electric organs of two strongly electric fish, the torpedo ray and the electric eel, were first studied in the 1770s by John Walsh, Hugh Williamson, and John Hunter. Charles Darwin used them as an instance of convergent evolution in his 1859 ''On the Origin of Species''. Modern study began with Hans Lissmann's 1951 study of electr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Osteoglossiformes
Osteoglossiformes , meaning "bony tongues" in Ancient Greek, is a relatively primitive order of ray-finned fish that contains two sub-orders, the Osteoglossoidei and the Notopteroidei. All of at least 245 living species inhabit freshwater. They are found in South America, Africa, Australia and southern Asia, having first evolved in Gondwana before that continent broke up. In 2008, several new species of marine osteoglossiforms were described from the Danish Eocene Fur Formation, dramatically increasing the diversity of this group. This implies that the Osteoglossomorpha is not a primary freshwater fish group with the osteoglossiforms having a typical Gondwana distribution. The Gymnarchidae (the only species being '' Gymnarchus niloticus'', the African knifefish) and the Mormyridae are weakly electric fish able to sense their prey using electric fields. The mooneyes (Hiodontidae) are often classified here, but may also be placed in a separate order, Hiodontiformes. Members ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Knifefish Continuous Waveform
Knifefish may refer to several knife-shaped fishes: *The Neotropical or weakly electric knifefishes, order Gymnotiformes, containing five families: **Family Gymnotidae (banded knifefishes and the electric eel) **Family Rhamphichthyidae (sand knifefishes) **Family Hypopomidae (bluntnose knifefishes) **Family Sternopygidae (glass and rat-tail knifefishes) **Family Apteronotidae (ghost knifefishes) *The featherbacks, family Notopteridae. *The aba, ''Gymnarchus niloticus'' *Four other unrelated fish species not in any of the above families: **Grey knifefish, ''Bathystethus cultratus''. **Blue knifefish The blue knifefish (''Labracoglossa nitida'') is a species of marine ray-finned fish, a member of the family Scorpididae. It is native to the Pacific Ocean waters off eastern Australia over to New Zealand, where it occurs at depths reaching fro ..., ''Labracoglossa nitida''. **Collared knifefish or finscale razorfish, ''Cymolutes torquatus''. ** Jack-knifefish, ''Equetus lanceolatus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Mormyridae
The Mormyridae, sometimes called "elephantfish" (more properly freshwater elephantfish), are a superfamily of weakly electric fish in the order Osteoglossiformes native to Africa. It is by far the largest family in the order, with around 200 species. Members of the family can be popular, if challenging, aquarium species. These fish have a large brain size and unusually high intelligence. They are not to be confused with the marine and brackish-water callorhinchid elephantfish (family Callorhinchidae) of Southern Hemisphere oceans. Description and biology The elephantfish are a diverse family, with a wide range of different sizes and shapes. The smallest are just in adult length, while the largest reach up to . They do, however, have a number of unique features in common. Firstly, their cerebellum is greatly enlarged, enabling them to interpret complex bio-electrical signals, and to the large size of the valve. Secondly, an auditory vesicle (a small bladder) is present insid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Caudal Fin
Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only by muscles. Fish fins are distinctive anatomical features with varying structures among different clades: in ray-finned fish (Actinopterygii), fins are mainly composed of bony spines or rays covered by a thin stretch of scaleless skin; in lobe-finned fish (Sarcopterygii) such as coelacanths and lungfish, fins are short rays based around a muscular central bud supported by jointed bones; in cartilaginous fish (Chondrichthyes) and jawless fish (Agnatha), fins are fleshy " flippers" supported by a cartilaginous skeleton. Fins at different locations of the fish body serve different purposes, and are divided into two groups: the midsagittal ''unpaired fins'' and the more laterally located ''paired fins''. Unpaired fins are predominan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
