Orcas, otherwise known as killer whales, are the largest of the dolphins and powerful predators. They're easy to identify from their distinctive black-and-white colouring and prominent, pointed dorsal fin.
In the wild, orcas can swim up to 65km a day and dive up to 150m several times a day. They cannot do this in artificial enclosures, which leads to boredom and stress.
In captivity orcas don't live much past 30 years, whereas in the wild they live from 50 to 80 years; in captivity they have killed humans, in the wild there are no recorded human fatalities.
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Why do captive orcas have drooping dorsal fins
Though drooping dorsal fins are occasionally seen in wild orcas, it does seem more common among captive animals – especially the longer-finned males. It’s not entirely clear why. The fins are supported by a tough protein called collagen, and one possibility is that, because captive animals spend more time at the surface, the protein is exposed to higher temperatures, which degrades its structure.
Dietary differences or reduced blood pressure as a result of lower activity may contribute, too. There is also evidence that, in a confined space, the animals must swim in tight circles, which exerts unnaturally high sideways forces on the fins.
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