Sunday 31 August 2014


Image: Phil's 1stPix
Amia calva
In the end, there can be only one. And that one has to do all the childcare.

So it is for the Bowfin, last of the Amiiforms.

Image: Brian Gratwicke
Amiiformes is an order of fish that arose during the Triassic period and became particularly abundant during the Jurassic and Cretaceous, leaving their fossils behind in almost every continent of the world. They lived in both marine and freshwater environments back then, but that was before the mighty Perciforms came along and conquered the world with their salmon and mackerel.

Species very similar to the modern Bowfin first arose some 100 million years ago. Today, all the other Bowfins and all the other Amiiforms are gone, leaving just Amia calva in the lakes and rivers of the eastern side of North America, clinging to life by the points of their numerous, sharp teeth. By which I mean they're doing quite well for the most part. They have really nice teeth.

Image: Phil's 1stPix
The Bowfin is usually placed within an infraclass called Holostei, which it shares with the Gars. They aren't particularly closely related - more like 20th cousins 8 times removed or whatever - but with all the mass extinctions that have gone on Gars are the closest relatives they have left.


As you can imagine, Gars and Bowfins share a few similarities, not least their ability to keep their heads when all about them are losing theirs to the fearful guillotine of extinction.

One odd similarity is that they live similar lifestyles and may share some of the same bodies of water. Bowfins are ambush predators who stick to slow-moving waters with lots of vegetation, where their drab, brown colouration affords them some camouflage.

Video: MNScuba

They approach shallow water at night to feed. A long dorsal fin adorns half their length, and ripples silently in the murk as they stalk their prey. With a burst of speed, and surprising agility when needed, they snatch any fish or crayfish that catches their eye. Bowfins can reach at least 50 cm (20 in) long, so they're willing and able to tackle a wide range of smaller prey.

Bowfins can sometimes turn up in unexpected places. When the rivers flood, they can range far and wide into all sorts of sluggish, oxygen-deprived waters most fish couldn't tolerate. They can do it because they can breath air. Like the Gars, they have a swim bladder with lots of blood vessels so that it can function as a kind of lung. In fact, when flood waters recede and an overly adventurous Bowfin finds himself stranded on land, laboratory tests suggest he might be able to survive out of water for the best part of a week!

Image: Uncle Chicken
So think about that before you get your fingers too close to all those sharp teeth.

Bowfins have a few other odd characteristics, like a gular plate. This is a large bone on the lower jaw and a very rare feature in modern fish. Also their skeleton is mostly cartilage, with just a thin layer of bone covering their... bones. Their scales are also rather bony, but much thinner and less akin to a suit of armour than those of the Gar. And who could forget the little tubes they have sticking out of their nostrils?

Image: Greg Laden
Something else happens during the spring - the males develop a rather striking green belly! I'm sure the ladies love his green belly but he'll need to do more than that if he wants to grab their attention. So he constructs a nest out of weeds on the bottom of the river and waits for a passing female to show some interest.

After a few hours of nudging and chasing and all sorts of delightful frolics, the female will hopefully lay her sticky eggs in his nest for him to fertilize. There may be some 50,000 of them! Females may have some eggs to spare and mate with another male, and the male can mate some more too and acquire yet more eggs. So it's fun for all the family, sort of.

Video: Michigan's Wildlife
A male guards his swarm of young

The male is left to defend the eggs with all the aggression his sharp teeth permit. They hatch within ten days and, just like the baby Gars, they have an adhesive organ on their snout which allows to attach themselves to plants. Their father continues to defend them from predators for another month until they're about 10 cm (4 in) long. At this point the youngsters say goodbye to their brothers and sisters and their diligent parent, and swim away to start their own lives.


Turns out Bowfins do have a family after all.


TexWisGirl said...

good single dadism!

Lear's Fool said...

Also: They're horrible for the environment because they use so much hand sanitizer

Joseph JG said...

@TexWisGirl: It's amazing! Parenting of any kind is unusual in fish, so cool that this ancient fellow struck upon it!

@Lear's Fool: Haha! Well at least they're careful!