Steller Sea Blog

Whales Share Phylogenetic Relationship with Dogs

During the Eocene, some 53 million years ago, the earth was home to a species of hoofed-mammals known as Pakicetids. Based on the anatomy of their fossil remains palaeontologists have established that Pakicetids looked somewhat like dogs with hoofed feet and long, thick tails. They are also believed to an early ancestor of whales based on the shape of their auditory bulla, a bone located in the inner ear. The shape of the ear region in Pakicetus is highly unusual and only resembles the skulls of whales. The feature is diagnostic for cetaceans and is found in no other species. The teeth of Pakicetus also resemble the teeth of fossil whales, being less like a dog’s incisors, with a serrated triangular shape, similar to a shark’s tooth, which is another link to more modern whales. Given their evolutionary relationship I found the article below to be rather interesting.

Poop Patrol
by Monique Keiran, Canadian Geographic

A Black Labrador named Tucker is helping researchers determine why orcas summering off southern Vancouver Island are dying off.

Tucker lends his nose to science by standing in a moving open-decked motorboat and sniffing the wind to detect orca scat floating on the surface of the Strait of Georgia and Haro Strait. His human colleagues, including Sam Wasser, director of the University of Washington’s Center for Conservation Biology, scoop up the greenish brown goo and later analyze its hormone levels.
“Killer whale scat doesn’t stay afloat long, and it’s about the same color as the water,” says Wasser, who uses dogs to study elephants, caribou, spotted owls and other at-risk species. “Without a dog, we’d have a hard time getting enough samples.”
Because Tucker can smell the poop from a long way off, the researchers needn’t crowd the whales. Preliminary analysis of hormones in the scat suggests that boat traffic stresses orcas.
The results from samples collected since 2006 also indicate the whales’ preference for chinook salmon may be causing them to starve. Stress hormones in the scat peak and thyroid hormones plummet from September through December, when the salmon are at their scarcest. Thyroid hormones help regulate metabolism. When the animal starves, levels drop and metabolism slows. Wasser says the hormone levels mirror observed orca death rates.
“In 2007, thyroid levels in the samples were highest, and no whales died. They were intermediate in 2006, when there was five percent mortality, and lowest in 2008, when mortality increased to eight percent.”
More samples are needed to confirm the results. Wasser and Tucker will return to the straits to patrol for poop this summer.

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