page_title: Bowfin
section_title: Morphology
hierarchical_section_title: Bowfin / Morphology
caption_attribution_description: Amia calva head. Caption: Amia calva L. (After Allis 1897, slightly altered) A, left-side view of the skull. B, left-side view of the cranium, from which the dermal bones have been removed. Cartilage is dotted. a.c, auditory capsule&#160;; au, , adnasal&#160;; ar, dermarticular&#160;; as, alisphenoid&#160;; bo, basioccipital&#160;; bst, branchiostegal ray&#160;; c, cartilaginous cranium&#160;; d, dentary&#160;; ep, epiotic&#160;; eth, mesethmoid&#160;; ex, exoccipital&#160;; f, frontal&#160;; fa, foramen for facial nerve&#160;; ff, foramen for vagus&#160;; h, hyomandibular&#160;; iop, interopercular&#160;; l, lachrymal&#160;; m.g. median gular&#160;; m-l- lateral line in mandible; mx, maxilla&#160;; n, neural arch&#160;; na, nasal&#160;; n.sp, neural spine&#160;; o, opisthotic&#160;; obs, orbitospenoid&#160;; oc. n, foramen for spin-occipital nerve&#160;; o.f. vacuity with optic foramen in front&#160;; olf, olfactory capsule&#160;; op, opercular&#160;; p, parietal&#160;; pf, prefrontal&#160;; pmx, premaxilla&#160;; po, prootic&#160;; pob, postorbital&#160;; pop, preopercular&#160;; pp, supratemporal&#160;; pt, post-temporal&#160;; ptf, postfrontal&#160;; q, quadrate&#160;; s, pterotic&#160;; s.a, supra-angular&#160;; sm, septomaxiliary&#160;; sop, subopercular&#160;; spm, supra-maxilla&#160;; t.f, trigemical foramen&#160;; v.c. vertebral centrum.
context_page_description: Bowfin are bony fish related to gars in the infraclass Holostei. Common names include mudfish, mud pike, dogfish, griddle, grinnel, swamp trout, and choupique. They are regarded as taxonomic relicts, being the sole surviving species of the order Amiiformes, which dates from the Jurassic to the Eocene, persisting to the present. Although bowfin are highly evolved, they are often referred to as "primitive fish" because they have retained some morphological characteristics of their early ancestors.
  Bowfin are demersal freshwater piscivores native to North America, and commonly found throughout much of the eastern United States, and in southern Ontario and Quebec. Fossil deposits indicate Amiiformes were once widespread in both freshwater and marine environments with a range that spanned across North and South America, Europe, Asia and Africa. Now their range is limited to much of the eastern United States and adjacent southern Canada, including the drainage basins of the Mississippi River, Great Lakes and various rivers exiting in the Eastern Seaboard or Gulf of Mexico.
context_section_description: The average length of a bowfin is 50 cm (20 in); females typically grow to 65–70 cm (26–28 in), males to 50–65 cm (20–26 in). Records indicate bowfin can reach 109 cm (43 in) in length, and weigh 9.75 kg (21.5 lb). Young of the year typically grow to 13–23 cm (5.1–9.1 in) by October. Females tend to grow larger than males.
  The body of the bowfin is elongated and cylindrical, with the sides and back olive to brown in color, often with vertical bars, and dark reticulations, or camouflaged pattern. The dorsal fin has horizontal bars, and the caudal fin has irregular vertical bars. The underside is white or cream, and the paired fins and anal fin are bright green. During larval stage, hatchlings from about 7–10 mm (0.28–0.39 in) total length are black and tadpole-like in appearance. At approximately 25 mm (0.98 in) total length they have been described as looking like miniature placoderms. They grow quickly, and typically leave the nest within 4 to 6 weeks after hatching. Young males have a black eyespot on the base of the tail (caudal peduncle) that is commonly encircled by an orange-yellowish border while the female's is black, if present at all. It is thought the purpose of the eyespot is to confuse predators, deflecting attacks away from the head of the fish to its tail, which affords the bowfin an opportunity to escape predation. The bowfin is so 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.
  The skull of the bowfin is made of two layers of skull, the dermatocranium and the chondrocranium. The chondrocranium layer cannot be seen because it is located below the dermal bones. The bowfin skull is made up of 28 fused bones, which compose the dermatocranium. The roof of the mouth is made up of 3 bones, the ectopterygoid, the palantine, and the vomer. The teeth are on two bones, the premaxillae and the maxillae. Another three bones make up the lower jaw the dentary, the angular, and the surangular. The cranial surface of the skull is made up of the nasals, the antorbital, the lacrimal, the parietal, the intertemporal, the post parietal, the supratemporal, the extra scapular, the post temporal, and the opercular. The entirety of the skull is attached to the girdle through another set of bones.
  Bowfin are often referred to as "living fossils", or "primitive fish" because they retained some of the primitive characters common to their ancestral predecessors, including a modified (rounded externally) heterocercal caudal fin, a highly vascularized gas bladder lung, vestiges of a spiral valve, and a bony gular plate. The bony gular plate is located underneath the head on the exterior of the lower jaw between the two sides of the lower jaw bone. Other distinguishing characteristics include long, sharp teeth, and two protruding tube-like nostrils. Unlike all of the most primitive actinopterygians, the scales of bowfin differ in that they are not ganoid scales, rather they are large, single-layered cycloid scales closer in similarity to more derived teleosts.
caption: Drawing of a bowfin skull showing the bony plates protecting the head
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