Platinum Alligator Gar: living fossils with a pigmentation disorder

Platinum Alligator Gar

These torpedo-shaped ‘living fossils’ with a flattened alligator-like head have been around since the days of dinosaurs, with fossil records tracing their existence to the Early Cretaceous over 100 million years ago. They can grow up to 3 metres in length and weigh up to 140 kilogrammes.

Here are more unusual facts about the rare Platinum Alligator Gars (Atractosteus spatula):

1. Their rare colour is due to Leucism

Alligator gars are typically brown or dark olive-green dorsally, fading to yellowish white ventrally. Platinum Alligator Gars’ snowy hue is the result of a pigmentation disorder called Leucism – a partial loss of pigmentation resulting in white, pale or patchy colouration of the skin, hair, feathers, scales or cuticles, but not the eyes.

Platinum Alligator Gar
Unlike albinism, Leucism is caused by a reduction in multiple types of pigment, not just melanin.

2. Breathes in air AND underwater

One reason why they managed to survive this long is their ability to thrive even in low oxygen waters. Like their ancestors from the dinosaur age, they have a swim bladder that they can use as a primitive lung. They fill this swim bladder by gulping air to supplement their gill breathing.

Platinum Alligator Gar
Their highly vascularised swim bladder is connected to the pharynx by a pneumatic duct, enabling them to use it as a primitive lung.

3. Ganoid scales that protect like chainmail

Unlike the flexible scales of other fishes, Platinum Alligator Gars have stiff, white enamel-like, jagged diamond-shaped ganoid scales that form an interlocking, protective armour similar to medieval chainmails.

Platinum Alligator Gar
These thick overlapping ganoid scales help to protect them from predators like large fish and alligators.

4. Two rows of teeth

Their upper jaw has two rows of fang-like teeth which are used to impale and hold prey. Platinum Alligator Gars are stalking, ambush predators feeding primarily on fish, but they will also eat water fowl and small mammals found floating on the water surface.

Teeth on the inner row of their upper jaw are longer than those on the outer row. Image credit: Cathleen Bester
Teeth on the inner row of their upper jaw are longer than those on the outer row. Image credit: Cathleen Bester

5. Slow to mature

As with most ancestral species, Platinum Alligator Gars are slow to mature. Most females reach sexual maturity only after 10 years while males reach sexual maturity in half that time.

Platinum Alligator Gar

6. Poisonous roe

A female Platinum Alligator Gar can produce about 150,000 eggs per spawn. The eggs are bright red and poisonous to humans if ingested.

 

We feed them fish and prawns on alternate days, and they are docile towards us when we dive clean the habitat.

——-– Alex Lee, aquarist in charge of Platinum Alligator Gars


These ‘swimming dinosaurs’ can be found at the Central and South American exhibits of S.E.A. Aquarium, located next to the Twilight Reef habitat.

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