for National Geographic News
The whale that spent two days in central London after swimming up the River Thames last week died from a combination of factors, including dehydration and damage to her muscles and kidneys, experts say.
They add that the whale lost its way while hunting squid.
Results of an autopsy on the bottlenose whale, which didn't survive a last-ditch rescue operation, were released today.
Veterinary scientists who carried out the tests say the 19-foot-long (5.8-meter-long), four-ton mammal probably swam into the North Sea by mistake before heading up the Thames in an attempt to get back to the Atlantic Ocean (see map of the region).
The postmortem also suggests that British Royal Navy sonar was not a factor in the animal's death, as has been speculated, nor were injuries she sustained while she was in the river.
The sexually immature female died on a rescue barge as she was being ferried back to sea last weekend. The sighting drew huge crowds in London and worldwide media coverage.
Scientists examined the whale's carcass at a dockside near Gravesend in Kent and samples were then taken back to the Zoological Society of London (ZSL).
Veterinary pathologist Paul Jepson, of the ZSL, said the whale's death "is believed to be the result of a combination of factors, including severe dehydration, some muscle damage and reduction of kidney function."
Jepson says whales and dolphins obtain water from their food and that northern bottlenose whales normally feed on deepwater squid in the Atlantic Ocean.
"This animal would not have been able to feed while in the North Sea and so it would have become dehydrated," he added.
Researchers say severe dehydration may also help account for damage to the whale's kidneys.
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