Determining age of whales
Name: Bruce W Walkey
While browsing through the Internet, I came upon a question
by two fifth grade students. Their question got me
thinking and now I pose it to you. How can you determine
the age of whales? Since they are mammals, can the methods
that are used on humans be used on whales? What are some
tests that can be done on bones or tissues to determine age?
Looking forward to your reply.
Although it is difficult to determine the age of whales (unless they
are born in captivity and we know their birth date), several methods
have been commonly used:
1) (if female) the examination of the ovaries
2) Examination of the ridges on baleen, which are not uniform in size
and analogous to tree rings. The problem with this is that baleen
wears away over time.
3) Studying layers of ossification in an ear bone is probably the most
accurate method of aging, since internal bones don't wear away.
The biggest problem with aging methods is that they usually require that
you are dissecting the animal, and often, we would like a method of aging
for live active animals. The best we can do here is to compare the size
and markings of whales of known age to those found in the wild.
Tom F Ihde
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Update: June 2012