A crew of marine life scientists gathered all the equipment they needed to conduct a whale version of an autopsy on a 38-foot-long humpback on a Oregon beach Monday -- but arrived to find it had disappeared.

"Last night's high tide must have pulled the big girl back out to sea," Tiffany Booth, part of the necropsy team from the Seaside Aquarium, said Monday. "The only thing we found was a kidney."

(Note: If you want to see what a whale kidney left behind on a beach looks like, click through the photo gallery.)

Booth explained how it was possible for the whale to leave that single organ behind. In doing so, she alluded to the infamous (and hilarious) mistake made by the Oregon Department of Transportation in the 1970s to try to get a whale carcass at Florence off the beach using dynamite.

"The whale had been dead for such a long time, before washing in, that it was bloated with gas. Once the whale hit the beach and the full weight of the whale pressed on all of that built up gas, the whale kind of exploded -- not like the gruesome scene from the infamous Florence whale, a little slower and oozier. So some of the internal organs got pushed out of the whale."

The kidney is quite large and weighed roughly 35 pounds, she said.

Marine experts who looked at the whale corpse up close over the weekend could not see an evident cause of death for the adult whale, which died at sea and washed up on the beach south of Cannon Beach on Friday. Humpback whales can live as long as 100 years, Booth said.

Humpback whales have the longest migration paths of any mammal. The ones that ply the sea off Oregon swim about 3,000 miles from breeding grounds to feeding grounds. They can typically be seen off the North Oregon coast in very late summer and early fall, Booth said. Last year, members of the majestic species were spotted in the Columbia River near Astoria and passing by Haystack Rock in Cannon Beach, she said.

The humpback that washed up on the beach just north of Oswald West State Park and was seen there this weekend had been dead for quite a while before it came ashore, Booth said. Its body was host to barnacle species that only grow on whales.

Booth said marine scientists assume the whale will wash ashore again, but Booth said, probably "in a location we will not be able to access. We will just have to wait and see."

-- Betsy Hammond