Giselle Veve
WFB 232 Ichthyology
Osteoglossiformes (Greek osteo-(bone) and –glossi (tongue))
Taxonomy:
Superclass Gnathostomata-jawed fish
Class Actinopterygii
Order Osteoglossiformes-bony tongues
6 Families: Hiodontidae (mooneye/goldeneye), Pantodontidae (African freshwater
butterflyfishes), Osteoglossidae (arwana), Notopteridae (featherbacks/knifefishes), Mormyridae,
Gymnarchidae (elephantfishes)
30 genera, ~217 species
VT Species: Hiodon tergisus (Mooneye)
Description: Well-developed teeth, no supramaxilla, caudal fin with 16 or fewer branched rays, caudal
fin skeleton (except in Hiodon), and intestine passes posteriorly to the left of the esophagus and stomach
(1). Mainly cycloid scales. Some can breathe atmospheric oxygen when needed, allowing them to live in
deoxygenated areas. There is usually some soft connection between the gas bladder and the ear with some
but not all. Some have long heads, while others have elephant like snouts, their mouth positions change
depending on what they feed on. They can range in length from 4/5 inches to 9 feet.
Habitat: Restricted to freshwater but some fossil forms have lived in brackish water. They generally tend
to live closer to the surface of water.
Distribution: North and South America, Africa, Australia, India, Bangladesh, the Malay Archipelago,
Thailand, Borneo, and New Guinea.
Ecology and life history: Mainly prey upon plankton, crustaceans (such as shrimp, earthworms, and
snails, and other aquatic invertebrates. Some species use aquatic plants to build their nests in which they
spawn in, although notopterids do not build a nest they establish a breeding territory (4). They can lay
from a few hundred eggs to a few thousand in some species. Some bony tongues are nocturnal while
others are active during the day, therefore they hunt at different hours of the day (3). When the water
surface becomes warmer these fish tend to swim to deeper waters where they can maintain cooler body
temperatures. Elephantfish and knifefish use electroreception as early warning signals for their
surroundings.
Additional details: Many are a delicacy and fished commercially due to economic value, some thought
to be overfished like Arapaima gigas, one of the largest freshwater fish in the amazon. Some species
practice mouth brooding, which can be performed by either mother or father depending on the species.
Electrical discharges from their electrical organs are in forms of pulses, and can range of an output of 120
to 300 pulses per second (have been recorded).
Recent research: Osteoglossiformes and Perciformes DNA nucleotide and amino acid sequences were
compared supporting monophyly of Osteoglossomorpha and some support present taxonomic grouping of
osteoglossomorphs. This study started a basis for the diversity of the islet organ, and likely the nature of
the products of its cells promoting further studies of this organ (6).
References used
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6.
Paxton, J. R. and W. N. Eshmeyer. 1998. Encyclopedia of fishes 2nd ed. Academic Press.
"Bony Tongues and Relatives: Osteoglossiformes - Physical Characteristics, Diet, Behavior And Reproduction, Bony
Tongues And Their Relatives And People, Freshwater Butterflyfish (pantodon Buchholzi): Species Account GEOGRAPHIC RANGE, HABITAT, CONSERVATIO." - JRank Articles. N.p., n.d. Web. 11 Mar. 2013.
<http://animals.jrank.org/pages/1985/Bony-Tongues-Relatives-Osteoglossiformes.html>.
"Osteoglossomorph." Academic Dictionaries and Encyclopedias. N.p., n.d. Web. 11 Mar. 2013.
<http://universalium.academic.ru/282100/osteoglossomorph>.
Nelson, J. S. 1994. Fishes of the World. 3rd. ed. Wiley and Sons, New York.
Bond, C. E. 1996. Biology of Fishes, 2nd. ed. Saunders College Publishing, Fort Worth
Youson, J.H., A. A. Al-Mahrouki, L.C. Graham, C. J. Montpetit, and D.M. Irwin. 2006. The fish endocrine pancreas:
Review, new data, and future research directions in ontogeny and phylogeny. General and Comparitive Endocrinology
p.105-115.