Peters's elephantnose fish

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"Elephant nose" redirects here. For the proboscis of an elephant, see Elephant § Trunk.

Peters's elephantnose fish
Gnathonemus petersii.jpg
Elephantnose fish

Least Concern (IUCN 3.1)
Scientific classification edit
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Osteoglossiformes
Family: Mormyridae
Genus: Gnathonemus
Species:
G. petersii
Binomial name
Gnathonemus petersii
(Günther, 1862)
Synonyms[1]
  • Gnathonemus brevicaudatus Pellegrin, 1919
  • Mormyrus petersii Günther, 1862
The elephantnose fish is a weakly electric fish which generates an electric field with its electric organ and then processes the returns from its electroreceptors to locate nearby objects.[2]

Peters's elephant-nose fish (Gnathonemus petersii) is an African freshwater elephantfish in the genus Gnathonemus. Other names in English include elephantnose fish, long-nosed elephant fish, and Ubangi mormyrid, after the Ubangi River. The Latin name petersii confirms it is named after someone called "Peters" (probably Wilhelm Peters), although the apostrophe is often misplaced and the common name given as "Peter's elephantnose fish". It uses electrolocation to find prey, and has the largest brain-to-body oxygen use ratio of all known vertebrates (around 0.6).[3]

Illustration (1864), the upper is Peters' elephantnose fish. The lower is a worm-jawed mormyrid (Campylomormyrus tamandua)
Peters's elephantnose fish in captivity.

Description[]

Peters's elephantnose fish are native to the rivers of West and Central Africa, in particular the lower Niger River basin, the Ogun River basin and in the upper Chari River. It prefers muddy, slowly moving rivers and pools with cover such as submerged branches.

The fish is a dark brown to black in colour, laterally compressed (averaging 23–25 cm (9.1–9.8 in)), with a rear dorsal fin and anal fin of the same length. Its caudal or tail fin is forked. It has two stripes on its lower pendicular. Its most striking feature, as its names suggest, is a trunk-like protrusion on the head. This is not actually a nose, but a sensitive extension of the mouth, that it uses for self-defense, communication, navigation, and finding worms and insects to eat. This organ, called the Schnauzenorgan,[4] is covered in electroreceptors, as is much of the rest of its body. The elephantnose uses a weak electric field, which it generates with specialized cells called electrocytes, which evolved from muscle cells, to find food, to navigate in dark or turbid waters, and to find a mate.

Peters's elephantnose fish live to about 6–10 years, but there are reports[citation needed] of them living even longer.

In the aquarium[]

Peters's elephantnose fish is one of the most commonly available freshwater elephantfish in aquarium stores in the United States. In the aquarium it is timid, preferring a heavily planted environment with subdued lighting, and thrives in a tank of more than 200 litres (44 imp gal; 53 US gal); favourable additions to the fish's aquarium environment are a pipe or hollow log, alongside soft, sandy substrate, allowing the fish to sift through it with its delicate extended lip.

The fish feeds on small worms (bloodworms being the most common) and aquatic invertebrates such as mosquito larvae, but will accept frozen or flake food. Elephantnose fish are typically kept in water of medium hardness with a pH of 6.8 to 7.2 and a temperature of between 26–28 °C (79–82 °F).

Elephantnose fish, though typically docile when kept in captivity, can be aggressive towards other species of fish, though some fare well in community aquarium environments. However, unless kept in an aquarium of over 400 l (88 imp gal; 110 US gal), elephantnose fish can behave aggressively territorial towards members of their own species, making it unrecommended to keep more than one in captivity.

The weak electrical impulses generated by this fish can be made audible by placing two electrodes in the fish tank that are then hooked up to an audio amplifier or a piezoelectric earbud. The elephant nose fish can use its electosensing to detect moving prey and worms in the substrate.

Although the elephantnose fish was once thought to have poor eyesight, it is now known to have good low light vision. Its eyes use a combination of photonic crystals, parabolic mirrors and a clustered arrangement of rods and cones.[5]

See also[]

Notes[]

  1. ^ "Gnathonemus petersii". Integrated Taxonomic Information System. Retrieved July 3, 2007.
  2. ^ Von der Emde, G. (1999). "Active electrolocation of objects in weakly electric fish". Journal of Experimental Biology, 202 (10): 1205–1215. Full text
  3. ^ Nilsson G (1996) "Brain and body oxygen requirements of Gnathonemus petersii, a fish with an exceptionally large brain" Journal of Experimental Biology, 199(3): 603-607. Download
  4. ^ Engelmann, Jacob; Nöbel, Sabine; Röver, Timo; Emde, Gerhard von der (2009-09-22). "The Schnauzenorgan-response of Gnathonemus petersii". Frontiers in Zoology. 6 (1): 21. doi:10.1186/1742-9994-6-21. ISSN 1742-9994. PMC 2760544. PMID 19772622.
  5. ^ "AAAS". Science.org. Retrieved 1 December 2021.

References[]

External links[]

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