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Bowfin
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Amiiformes
Family:	Amiidae
Subfamily:	Amiinae
Genus:	Amia Linnaeus, 1766
Species:	A. calva
Binomial name
Amia calva Linnaeus, 1766

Template:Primitive fishes

The bowfin (Amia calva) is a species of basal bony fishes related to the alligator gar in the taxon Holostei. Common names are "dogfish", "grinnel", and "mudfish". The bowfin can be considered a taxonomic relict, being the last surviving member of the order Amiiformes (which includes three additional, now-extinct families dating from the Jurassic, to the Eocene), and of the family Amiidae (which contains numerous species in about four subfamilies, only one of which, Amiinae, is extant).

The bowfin is a freshwater piscivore commonly found throughout the Mississippi drainage system in the eastern United States. Their preferred habitat includes vegetated sloughs, lowland rivers and lakes, swamps, and backwater areas. They prey on fish and larger aquatic invertebrates by ambush or stalking. Bowfin are often improperly referred to as "primitive fish" because they have retained morphological characters common with ancestors of modern fish.

Like their distant relative the alligator gar, bowfin have gills for breathing, but they also have a vascular swim bladder lung that not only serves to maintain buoyancy, it allows them to breathe air through a small duct connected from the esophagus to the gastrointestinal tract. They break the surface to gulp air, and are able to live under conditions of aquatic hypoxia that other fishes could not survive. They can also survive periods of drought by burrowing into muddy substrate where they lie torpid.

Description and biology

The bowfin is named for its long, undulating dorsal fin consisting of 145 to 250 rays, and running from the middle of the back to the base of the tail. They are considered primitive, or ancient fish because they have retained certain primitive characters that date back to the early fossil record, including a modified (rounded externally) heterocercal caudal fin, a swim bladder lung, vestiges of a spiral valve, and a bony gular plate underneath the head. They can grow to 109 cm (43 in) in length, and weigh 9.75 kg (21.5 lb). Other noticeable features are the black "eye spot" usually found high on the caudal peduncle, and the presence of a gular plate. The gular plate is a bony plate located on the exterior of the lower jaw, between the two sides of the lower jaw bone.

Bowfin have two distinct air-breathing mechanisms used to ventilate the gas bladder. Type I air breaths are consistent with the action of exhale-inhale stimulated by aerial or aquatic hypoxia to regulate O2 gas exchange; type II air breaths are by inhalation alone which is believed to regulate gas bladder volume for buoyancy control.

The bowfin is an indiscriminate predator that readily preys on a broad variety of arthropod and vertebrate prey, from insects and crawfish to other fish and frogs.

The male bowfin exhibits extensive parental care. The male clears an area in the mud for the female to lay eggs in, and then fertilizes them. He hovers nearby and aggressively protects the eggs and the fry after they emerge.

Evolution

The bowfin is considered an evolutionary indicator, a window to the fossil past of bony fishes. Based on a mitogenomic perspective on the phylogeny of "ancient fish", the basal actinopterygians comprise four major lineages, including Polypteriformes, acipenseriformes, Lepisosteidae, and Amia calva. Following the radiation of basal actinopterygians, fossil records indicate the evolution of a new lineage of ray-finned fishes in the Late Permian Epoch which grew to prominence in the Mesozoic and Cenozoic Eras.

Neopterygians are the second major occurrence in the evolution of ray-finned fishes, and are distinguished from their earlier ancestors by major changes to the jaws, shape of the skull, and tail. Neopterygians include four main groups of fishes:

• the semionotids, (now extinct), appeared in the Permian Period, and were small, streamlined swimmers that occupied freshwater and marine habitats;
• the lepisosteids which include extant species of garfishes that first appeared in the Cretaceous,
• the bowfins (halecomorphids) the only extant species in the order Amiiformes which date back to the Triassic Period, and
• the stem group of Teleostei from which modern fish arose, including most of the bony fish we are familiar with today.

References

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2. Natural History Collections. "Subclass Actinopterygii: Relict Species of Ray-Finned Fish & Origin of Teleosts". University of Edinburgh. Retrieved June 2, 2014.
3. "Bowfin". Net Industries, LLC. Retrieved June 2, 2014.
4. ^ Jared Handley and Jesse Fielder (2004). "The Skeletal System of the Bowfin (Amia calva)". Murray State University.
5. Nelson, Joseph S. (2006). Fishes of the World. John Wiley & Sons, Inc. ISBN 0-471-25031-7
6. Froese, Rainer; Pauly, Daniel (eds.). "Family Amiidae". FishBase. January 2009 version.
7. Hedrick MS, Jones DR (January 1999). "Control of gill ventilation and air-breathing in the bowfin amia calva". National Center for Biotechnology Information.
8. Berra, Tim M. (2001). Freshwater Fish Distribution. San Diego: Academic Press. ISBN 0-12-093156-7
9. Inoue JG, Miya M, Tsukamoto K, Nishida M. (January 2003). "Mol Phylogenet Evol". Academic Press. {{cite journal}}: Cite journal requires |journal= (help)CS1 maint: multiple names: authors list (link)
10. Thom Holmes (June 28, 2008). The First Vertebrate. Chelsea House Publishers. p. 144.

Sepkoski, Jack (2002). "A compendium of fossil marine animal genera". Bulletins of American Paleontology. 364: p.560. Retrieved 2011-05-17. {{cite journal}}: |pages= has extra text (help)

Catherine A. McCormick. 1981. Central Projects of the lateral line and eight nerves in the bowfin,Amia Calva. The Journal of Comparative Neurology 197:1-15.

JM Conlon, JH Youson, and J Whittaker. 1991. Structure and receptor-binding activity of insulin from a holostean fish, the bowfin:Amia Calva. Biochem J. 276:261-264.

T M Nguyen, T P Mommsen, S M Mims, and J M Conlon. 1994. Characterization of insulins and proglucagon-derived peptides from a phylogenetically ancient fish, the paddlefish: Polyodon spathula. Biochem J. 300(Pt 2): 339–345.

J M Conlon, J H Youson, and T P Mommsen. 1993. Structure and biological activity of glucagon and glucagon-like peptide from a primitive bony fish, the bowfin: Amia calva. Biochem J. 295(Pt 3): 857–861.

External links

• MN DNR

• Bowfin Anglers' Group
• FishBase info for Amiidae
• Bowfin info by Brent Courchene
• Bowfin Taxonomy

• Amiiformes
• Fish of North America
• Fish of the Great Lakes
• Living fossils
• Freshwater fish of Florida
• Primitive fish