Mermaids, Dugongs, and the “hand of evolution”

by Rita Dal Martello

The other day while I was at the Grant Museum for my weekly engagement session, a visitor stopped me while I was passing by the full skeleton of an adult male dugong.

“Is this real?!” he asked me in awe. The reason for his stupefaction is quite understandable when looking closely at the skeleton of this large marine mammal. Dugongs have a hand-like structure hidden in their flippers, which make their skeletons look like as if they have human arms attached to their torso.

Dugong is a Malay word meaning “lady of the sea”; they belong to the order Sirenia, which also includes manatees. The word manatee comes from Latin manatus, which means “having hands”. They are collectively called sea-cows as they feed primary from sea-grass grazed on the bottom of the sea.

Dugongs and manatee are responsible for the birth of the legend on the existence of the most inspiring mythical creatures: the mermaids.

European explorers sighted them in tropical waters during their travels both to the Americas and to Australia. Similar to how humans turn their heads to look behind them, so do dugongs, potentially causing the sailors to mistake the sea-cows for humans. But mermaids’ legends started long before the European colonialist travels around the world. 5000-year-old Neolithic cave paintings depicting dugongs have been found at the Tambun Cave in Ipoh, Malaysia.

Interestingly, the hand structure in the fins of sirenians is often taken as one piece of evidence for species evolution. About 350 millions years ago amphibians evolved on earth. The terrestrial fingers and toes in the amphibians come from structures already present in the fins of fishes, and the same structure continued evolving in later reptiles, birds, and eventually mammals. The limb structure seen in dugongs is shared among all mammals, including dolphins, and humans.

Dugongs were once distributed along the tropical warm waters between the East African Coast, the Indian Ocean and the Australian coasts. They were hunted for meat and oil for centuries, and can now be found only at the Great Barrier Reef in North Australia and South of New Guinea. They are listed as vulnerable to extinction by the International Union for Conservation of Nature.

If you don’t want to travel quite so far, you can find the Grant Museum’s Dugong just past the front desk, in the right corner of the main room.