Physeter Follow-Up

After I posted this photo of a sperm whale from Ogasawara to Flickr, I received a comment/ question from Rick Pearson.

Friendly sperm whale encountered west of Chichijima, Ogasawara
Photograph taken under permit

Here's Rick's comment:

Hey Tony, any more info about this particular whale? Is it a male (kinda hard to tell from this angle), and how big was it? I went to your blog page and didn't find much more info there, just that it was very friendly. The reason I'm asking, is that the entire front, flattened portion of it's head is gray, and there are lots of scars all over the head and around the mouth. I haven't seen that much gray in any underwater sperm whale photo, and according to both scientists, and the old time Yankee whalers, that much gray on the front was most often found only on older, and therefore much larger, male sperm whales.

I certainly noticed the grey colouration right away when we came across this whale, largely because it made the whale easy to spot, but also, as Rick alludes to, most sperm whales don't seem to have so much grey.

I wasn't aware of any possible correlation with the whale's age or sex, however.

Anyway, I promised Rick I'd find and post another photo of the same whale, showing the underside so we can at least decide if it's a male or not, so here it is:

Sperm whale hanging in the water
Photograph taken under permit

And here's a zoomed-in view of the genital area:

Close-up of the whale's underside
Photograph taken under permit

The whale wasn't very big, at least as far as sperm whales go. I'd estimate it was 12 metres long at most, and it didn't have the bulk of a mature male. I've been in the water with two mature bull sperm whales, and believe me...when you see a big know it!

Anyway, the colouration is intriguing. If anyone else has any insights or relevant knowledge, please share!