Bowfin

• It is the sole survivor of its family, the amiids, a lineage that was dominant more than a hundred million years ago. Hence it is called a living fossil.
• It breathes air with its swim bladder, which is highly vascularised and connected to the oesophagus, working as a primitive lung. In severe hypoxia and with the water at 30 °C, up to 70% of the oxygen it consumes is taken from the air.
• It retains several archaic traits: a modified heterocercal tail, remnants of a spiral valve in the intestine and a bony gular plate under the lower jaw.
• Its scales, however, are not ganoid like those of primitive fishes: they are cycloid, like those of modern teleosts.
• The male digs a nest among the vegetation, guards the eggs and then escorts the swarm of fry, defending them aggressively until they disperse.
• A 2022 phylogenomic analysis found unrecognised species diversity within what used to be called Amia calva, which has led to Amia ocellicauda being revalidated as a species in its own right.

Skeleton type

Vertebrate - internal bony skeleton (bony fish)

Habitat & environment

Backwaters, oxbows and densely vegetated lagoons of eastern North America, in warm, oxygen-poor waters where other predators cannot cope

Sexual maturity

4.2 years

Sources consulted: https://es.wikipedia.org/wiki/Amia_calva