Information about mormyrid

Elephant fish

Blunt-jawed elephantnose (Gnathonemus tamandua)

Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Osteoglossiformes
Family:	Mormyridae

Subfamilies

Mormyrinae
Petrocephalinae

The family Mormyridae, sometimes called elephantfish, are freshwater fishes native to Africa in the order Osteoglossiformes. It is by far the largest family in the order with around 200 species.

Members of the family are popular, if challenging, aquarium species, notable for their ability to generate weak electric fields that allow the fishes to sense their environment in turbid waters where vision is impaired by suspended matter. The generation of these electric fields and their use in providing the fishes with additional sensory input from the environment is the subject of considerable scientific research, as is research into communication between and within species.

Electric discharges are most often pulsitile discharges, with Gymnarchus niloticus being an exception to this rule, discharging its electric organ near approximately 500 Hz, giving it a near-sinusoidal like discharge. The electric organ is a structure that is well established in the scientific literature to be developmentally related to muscle, as in Gymnotiform electric fish, as well as in electric rays and skates. There is a surprising degree of convergent evolution between the South American Gymnotiforms and the African Mormyridae, particularly in the sensory apparatus for detecting and processing electrical signals involved in electrolocation and electrocommunication.

Some species possess modifications of the mouthparts to facilitate feeding upon small invertebrates buried in muddy substrates, the shape and structure of these leading to the popular name of "elephant nosed fish" for those species with particularly prominent mouth extensions. The extensions to the mouthparts (usually consisting of a fleshy elongation attached to the lower jaw) are flexible, and equipped with touch (and possibly taste) sensors.

Among those members of the family lacking extended mouthparts, the body shape and general morphology of the fishes has led to some being known among aquarists by the name of "baby whale", despite the fact that true whales are mammals. Other "mormyrid mammalian misnomers" include the term "dolphin fishes", in reference to certain members of the Genus Mormyrops.

Classification

Subfamily Mormyrinae
Subfamily Petrocephalinae

Genera and Species

The family Mormyridae contains the following Genera:

Boulengeromyrus
Brienomyrus
Campylomormyrus
Genyomyrus
Gnathonemus
Heteromormyrus
Hippopotamyrus
Hyperopisius
Isichthys
Ivindomyrus
Marcunesias
Mormyrops
Mormyrus
Oxymormyrus
Paramormyrops
Petrocephalus
Pollimyrus
Stomatorhinus

Among the species that belong to this family are:

Gnathonemus petersi, Peters' elephantnose fish;
Gnathonemus tamandua, the Blunt-jawed elephantnose;
Gnathonemus elephas;
Marcunesias macrolepidotus;
Marcunesias senegalensis;
Pollimyrus castelnaui, known among aquarists as the "baby whale"', along with other relatives in the genus Pollimyrus;
Pollimyrus isidori;
Brienomyrus niger, the "black baby whale";
Campylomormyrus rhynchophorus;
Hippopotamyrus discorhynchus;
Mormyrops deliciosus, a large member of the family utilised as a food fish by humans;
Petrocephalus catostomus, the smallest member of the family (7 cm SL);
Mormyrus lapinus, sometimes called the "dolphin fish" or "freshwater dolphin" by aquarists;
Brienomyrus brachyistius, the "brown baby whale"

Sources

"Mormyridae". FishBase. Ed. Ranier Froese and Daniel Pauly. January 2006 version. N.p.: FishBase, 2006.
One of several papers on electrogenesis and electric field sensing in Gnathonemus petersi
Detailed research paper on the sensory and central nervous systems in Gnathonemus petersi
Another page covering the electrosensory capabilities of Mormyrid fishes
Mormyrids in the aquarium
summary of a research on the blue jawed elephant nose from JEB

Scientific classification or biological classification is a method by which biologists group and categorize species of organisms. Scientific classification also can be called scientific taxonomy, but should be distinguished from folk taxonomy, which lacks scientific basis.
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Chordata
Bateson, 1885

Typical Classes

See below

Chordates (phylum Chordata) are a group of animals that includes the vertebrates, together with several closely related invertebrates.
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Actinopterygii
Klein, 1885

Subclasses

Chondrostei
Neopterygii
See text for orders.
The Actinopterygii (the plural form of Actinopterygius) comprise the class of the ray-finned fishes.
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Osteoglossiformes

Families

Suborder Notopteroidei

Gymnarchidae
Mormyridae (elephantfishes)
Notopteridae (featherfin knives)
Ostariostomidae (extinct)

Suborder Osteoglossoidei

Heterotididae

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Africa is the world's second-largest and second most-populous continent, after Asia. At about 30,221,532 km² (11,668,545 sq mi) including adjacent islands, it covers 6% of the Earth's total surface area, and 20.4% of the total land area.
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Osteoglossiformes

Families

Suborder Notopteroidei

Gymnarchidae
Mormyridae (elephantfishes)
Notopteridae (featherfin knives)
Ostariostomidae (extinct)

Suborder Osteoglossoidei

Heterotididae

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aquarium (plural aquariums or aquaria) is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Aquaria are primarily used for fishkeeping, although invertebrates, amphibians, marine mammals, and aquatic plants
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electric field. This electric field exerts a force on other electrically charged objects. The concept of electric field was introduced by Michael Faraday.

The electric field is a vector field with SI units of newtons per coulomb (N C⁻¹
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Gymnarchidae

Genus: Gymnarchus
Cuvier, 1829

Species: G. niloticus

Binomial name
Gymnarchus niloticus
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For the musical instrument, see Electronic organ.

The electric organ is a myogenic organ common to all electric fish used for the purposes of creating an electric field, a behavior used for navigation as well as communication in natural
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Hz or hz may mean:

Herero language (ISO 639 alpha-2, hz)
Hertz, unit of frequency

HZ, in all capitals, can stand for:

Hazard
Herpes Zoster
Horizons, a computer game

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sine wave or sinusoid is a function that occurs often in mathematics, physics, signal processing, electrical engineering, and many other fields. Its most basic form is:

which describes a wavelike function of time (t) with
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MUSCLE (multiple sequence comparison by log-expectation) is public domain, multiple sequence alignment software for protein and nucleotide sequences.
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Gymnotiformes

Families

Apteronotidae
Gymnotidae
Hypopomidae
Rhamphichthyidae
Sternopygidae

The Gymnotiformes is a lineage of ostariophysan teleost electric fishes.
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In evolutionary biology, convergent evolution is the process whereby organisms not closely related (not monophyletic), independently evolve similar traits as a result of having to adapt to similar environments or ecological niches^[1].
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Electroreception, sometimes written as electroception, is the biological ability to receive and make use of electrical impulses. It is much more common among aquatic creatures, as water is a far superior conductor than air.
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Invertebrate is an English word that describes any animal without a spinal column. The group includes 97% of all animal species — all animals except those in the Chordate subphylum Vertebrata (fish, reptiles, amphibians, birds and mammals).
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whale can refer to all cetaceans, to just the larger ones, or only to members of particular families within the order Cetacea. The last definition is the one followed here. Whales are those cetaceans which are neither dolphins (i.e.
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Mammalia
Linnaeus, 1758

Subclasses & Infraclasses

Subclass †Allotheria*
Subclass Prototheria
Subclass Theria

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Gnathonemus

Gnathonemus is a genus of fish in the Mormyridae family. It contains the following species:

longnose stonebasher (Gnathonemus longibarbis)
Peters' elephantnose fish
Blunt-jawed elephantnose

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Hippopotamyrus

Hippopotamyrus is a genus of fish in the Mormyridae family. It contains the following species:

Graham's stonebasher (Hippopotamyrus grahami)

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Mormyrus

Mormyrus is a genus of fish in the Mormyridae family. It contains the following species:

Bernhard's elephant-snout fish (Mormyrus bernhardi)
Mormyrus caschive
Mormyrus hildebrandti

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Pollimyrus

Pollimyrus is a genus of fish in the Mormyridae family. It contains the following species:

dark stonebasher (Pollimyrus nigricans)

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G. petersii

Binomial name
Gnathonemus petersii
(Günther, 1862)

Peters' elephantnose fish (Gnathonemus petersii; syn.
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G. tamandua

Binomial name
Gnathonemus tamandua
(Günther, 1862)

The blunt-jawed elephantnose, Gnathonemus tamandu, is an elephantfish in the genus Gnathonemus.
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FishBase is a comprehensive database of information about fish. As of October 2006, it included descriptions of over 29,400 species, over 222,300 common names in hundreds of languages, over 42,600 pictures, and references to more than 38,600 works in the scientific literature.
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