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My harbour porpoise skull

Jake

If you were looking carefully when I wrote about my new room you would have noticed that one of the skulls I have put on display is a harbour porpoise ! If you know about skulls, you probably know that they are pretty cool. 

To start with they are technically from the whale family (cetacea). The whale family has two subgroups, one is those with teeth, and the other is Baleen whales which suck in water through stretched tissue. The harbour porpoise and dolphins are from the toothed family, even though this skull doesn't have teeth.
This was a gift from Mr Evans who is a very kind man from the north of Scotland who also gave me a pretty cool book and the otter skeleton. He found the skull in 1998 and it has the place and date it was found written on it.



The harbour porpoise is one of the smallest cetaceans, and the skull is 22cm long (about the same length as the one on Skullsite). Porpoise and dolphin skulls are very different to other mammals. Almost all of the main bit of the skull is taken up with the braincase. The nose is very thin and broad, and what I think are the holes for the nasal tubes go from top to bottom just before the braincase, not front to back like canids or deer. It seems smoother than my seal skull. The eyes would be on top of the smooth parts, but I can't see the holes where the optic nerve would go into the brain.


The rostrum, which is the nose part, is just 8.5cm of the length of the skull. Dolphins have much longer rostrums.


This is the skull upside down. The grooves are where the teeth should be, but the teeth have long fallen out.


The spine goes into the back of the skull, not the underneath like on some other mammals, which makes sense because the porpoise lies flat in the water and can't move the head much. There are two holes where I think the skull was thin. It doesn't look like it has been hit or broken. Inbetween the holes are some thin grooves that were maybe muscle attachments.


The earbones are missing on both sides. Although they are not there, the hollows they left make the earbones look big in proportion to the skull.


Cetaceans are protected, so in the UK you need to apply for a licence to keep their bones. In Scotland you apply to Scottish Natural Heritage. I had this skull added onto my main licence which I need for my pipistrelle bat skeleton and my otter.


This was a fantastic gift, especially because I don't get to do much beachcombing. Thank you again to Mr Evans !

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2 comments :

Psydrache said...

Oh, you have seen one alive? Cool!
As you may now I own such a skull as well. They are very interesting and now I have some pictures for to compare.

Jake said...

I've never seen a live one ! The picture of one isn't mine.




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