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Specimen of the Week: Week Twenty
By Emma-Louise Nicholls, on 27 February 2012
Another Monday morning closer to March and the beautiful Spring I am looking forward to. I am not a winter person- give me 35 degrees in the shade any day. My house has been freezing over the winter period and I am getting tired of wearing 900 layers and walking around looking like the Michelin (wo)man. How I wish I lived in a warmer country! Another animal that is struggling in its habitat at the moment is long, blubbery and pink-ish. This week’s specimen of the week is:
**!!!The Ganges River Dolphin!!!**
Ganges river dolphin skeleton (Platanista gangetica) at the Grant Museum of Zoology. LDUCZ-Z2282
1) Only recognised as a unique species in the 1970s, the Ganges river dolphin is grey-pink and stocky, with a long, thin beak. Unlike ocean dwelling dolphins, the Ganges river dolphin has a triangular shaped ridge in place of a properly developed dorsal fin.
2) The local name for the Ganges river dolphin is ‘susu’. It is thought that this is an onomatopoeic word which refers to the sound the river dolphin makes when it breathes above water.
Ganges river dolphin skull
3) The eye of a Ganges river dolphin lacks a lens, meaning it has terrible eyesight. However, it doesn’t much care that it lacks the external ears to hold up a pair of glasses. The rivers in which it lives are so muddy that good glasses wouldn’t be worth the money. Its eyes can only detect the direction of light and so it relies on its epic skills as an echolocator for both feeding and navigation.
4) The Ganges river dolphin is listed as endangered on the IUCN Redlist. The drainage area of the Ganges river where this species lives, is also home to approximately one tenth of the world’s entire population of humans. Although the dolphin has a number of problems, its main woe is the prevention of seasonal migrations and the isolation of individual populations, due to the damming of rivers for irrigation and the generation of electricity.
A nice set of gnashers
5) The Ganges river dolphin likes to play. It can be seen swimming along with its beak held high out of the water. As it is near blind it is probably not out to enjoy the scenery, plus, there are no fish to speak of in the air just above the river, so it has therefore been presumed that the dolphin does this for giggles. It is also a fan of breaching, in which it will jump partly, or completely out of the water, and then come crashing down in a sideways belly flop, onto the side of its body.
We have a whole mounted skeleton of a Ganges river dolphin in the museum, and it sits pride of place by the door. Can you spot what is unusual about our skeleton though? Come and tell me if you do.