The bowfin is a large, air-breathing carnivorous freshwater fish. They earn their name due to the single dorsal fin
which stretches from the back of the neck to their tail. Bowfins are olive coloured dorsally and cream coloured ventral
ly. They are covered with small cycloid scale
s which lack ctenii (tiny tooth-like projections), giving them a very smooth texture. Their heads are not covered in scales, unlike most fish species
. The bowfin's lower jaw includes a gular plate, giving them a particularly robust and rigid mouth. This gular plate is not found in any other fish species. They grow to be approximately 70 centimeters long, with some rare specimens topping a meter in length. The largest bowfins can weigh upwards of 5 kilograms.
Bowfins can be found throughout the mid-west and northern United States, as well as the St. Lawrence seaway. They are most often found in ponds and marshes which are unsuitable to their main competitors, bass and pike. In fact, these species are not found together very often (this is a good example of competitive exclusion). Bowfins are often found in shallow, poorly oxygenated bodies of water and can exist easily in these environments because their air bladder has evolved for use in respiration. The fish can swallow air directly into the air bladder, which is highly vascularized, and oxygen can be extracted from this air.
The large bowfin is a voracious feeder, and stomach contents have revealed that the species can eat fishes of all kinds, frogs, crayfish, insects, leeches and just about anything else it can get into its mouth. They are preyed upon by almost no other species due to their large size, but young-of-the-year fishes are often consumed by adults (intraspecific cannibalism).
The bowfin reproduces in the early spring. When the water temperature rises above 16 oC, the male will construct a nest in a weedy area. He nibbles off the tops of the weeds, and clears the bottom with his fins. This leaves a bed of tender macrophyte roots protruding from the gravel or sand. A female who finds the male and his nest to her liking will lay down in the nest, and the male will position himself along side her. They will then release their eggs and sperm, with the female leaving roughly 2000 to 5000 eggs per nest. The species is polygamous, as a large female may lay roughly 20000 eggs during the spawning period, and the eggs in a single nest appear to come from more than one female. The male remains to protect the embryos and will remain until the eggs hatch and the larvae attain a size of about 10 centimeters.
The species is not generally targeted by anglers, seeing as their flesh has a rather unpleasant odour and taste. Despite this lack of pressure from anglers and predatory species, the bowfin is considered threatened or endangered throughout its range given the relative paucity of suitable habitat.
The bowfin is an evolutionary relic, and is the sole species in its order. The Amiidae date back to at least the Jurassic period, roughly 180 million years ago. Fossil remains of now extinct species in the Amiidae are found all over Europe and the United States. Their scientific name, Amia calva is derived from two sources. First, Amia refers to an ancient Greek name for a fish (most likely the bonito). Second, calva means smooth in Latin.
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