American Paddlefish: living fossils that appeared before the dinosaurs

The American Paddlefish (Polyodon pathula) is native to the Mississippi River basin. Fossil records date its first appearance to around 300 million years ago – nearly 50 million years before the first dinosaurs appeared.

Image by Ng Boon Ping

No bones, no teeth

The American Paddlefish is also referred to as a primitive fish because it retains some morphological characteristics of its early ancestors. These include a cartilaginous skeleton, a paddle-shaped rostrum that extends nearly one-third its body length, and a caudal fin similar to that of sharks.

See? No bones, just cartilage. Image by Ng Boon Ping.

Over time, this fish has evolved with adaptations such as filter feeding. Its rostrum and cranium are covered with tens of thousands of sensory receptors for locating zooplankton. Being a filter feeder, it swims with its mouth open, using comb-like structures called gill rakers to strain zooplankton from the water. As such, the American Paddlefish has no need for teeth.

Image by Ng Boon Ping

Hatched without a rostrum

The American Paddlefish’s rostrum is an extension of its cranium, not of the upper and lower jaws or olfactory system as with the long snouts of other fishes. Here’s another fun fact about its iconic rostrum: it only begins to form shortly after hatching.

Varying development of three 30-day-old American Paddlefish fry. Source: Wikipedia

Classified as vulnerable on IUCN Red List

American Paddlefish populations have declined dramatically mainly due to overfishing, habitat destruction, and pollution.

Poaching has also been a contributing factor to their decline. Prized for their caviar, the problem of poaching will continue to be as long as the demand for caviar remains strong.

Image by Ng Boon Ping

Come within inches of these living fossils at S.E.A. Aquarium. With Spooky Seas happening now till 28 October 2018, there are interactive activities around the aquarium to help everyone, especially the kids, learn more about these amazing fish and other quirky sea creatures. Details here

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