Whale Kidney Stone

Original content by: Dr. Leon Fay

zoomable artifact image here

About This Artifact

A whale kidney stone? It looks almost like an egg, but as mammals, whales give birth to live young. What is a kidney stone? A kidney stone is a hard object that may form in the urine after the kidney has filtered the blood. When various waste or excess – not needed - substances such as calcium, uric acid and oxalate are filtered out, they may come together especially if there are too many of one kind and/or there is not enough body liquid. Dietary habits and infections in the kidneys can also lead to stone formation. Kidneys in whales share similarities in structure and function with those in humans. In humans, the two kidneys resemble kidney beans. In a whale, they resemble a large bunch of grapes packed closely together and their size corresponds to how large they are. When formed, stones can be of varying sizes and shapes.

Very few whale kidney stones have been recovered and those are primarily from whales that have been stranded and died. This contrasts with the number of stones studied from other cetacean family members, dolphins and porpoises. As a perspective, in the United States, it is estimated that 1 in 11 persons may have kidney stones in their lifetime. In whales? Totally unkown.

There are at least four examples of analyzed recovered whale kidney stones to point to. One was from a 9.7 foot pygmy sperm whale beached in 2002. The stone weighed ½ pound and was composed of a mineral called struvite from a bacterial infection in the kidneys. A second example is that of a 2014 beached female bowhead whale that was 34.8 feet long and had 20 very small stones no larger than ¼ of an inch. The stones were entirely of calcium oxalate. The third was from a 2014 beached pregnant sperm whale that was 29.4 feet long and weighed 17,680 lbs. The stone was greenish black, weighed 4.1 lbs and made primarily of ammonium oxalate. This whale had evidence of kidney blockage with severe kidney damage. The particular stone featured in this image is from an unknown whale source. It measures about 7 ½ inches and consists primarily of magnesium, according to testing.

Kidney stones in whales can have serious consequences, as in humans. While it is difficult to prove in whales, blockage in the urinary system due to a large enough stone can lead to severe pain. Blockage that continues may lead to the kidney(s) swelling and eventually failing in its function. If both kidneys are involved, it will lead to death. But at least in humans, most stones are eventually passed through the urinary system.

Questions for Further Thought

  1. Do you know anyone who has suffered the pain associated with a kidney stone? How do you imagine a whale going through such an experience?
  2. Ambergris is a gray or black substance that is also expelled by a whale. What is it? What was finally figured out about this? How did the fate of ambergris differ from kidney stones? (Hint: See article about ambergris under "Related Items" to the left.)