Today we were surrounded by a massive pod of long finned pilot whales (Globicephala melas). It was an amazing sight to see as the rode the massive swell. At one point there seems to be at least 50 individuals including very young individuals as well as massive bulls (males). Check out the short video I managed to take below as they swam across our bow.
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There is lots I wanted to talk about this week and wasn’t sure where to start. There has been quite a lot of interesting marine mammal and marine developments going on.
What has most excited me and come back into the news a lot is the expansion of the marine protected area in the Pacific – Pacific Remote Islands Marine National Monument – which has been massively expanded through President Obama using his executive powers and the antiquities act to bypass congress and set up the largest marine protected area in the world. The area is being enlarged to more than 490,000 square miles from just over 87,000 square miles that were initially protected by President Bush.
This creation is very positive news as the area is going to be a fully protected no take zone with no commercial fishing or other marine degrading actives allowed. This large area will protect deep sea coral reefs and underwater sea mounts which, are hot spots for biodiversity alongside large areas of ocean that are important for migrating species including marine mammals such as humpback whales as well as sea turtles, bull sharks and tuna species.
Did whale evolution keep the unconnected “floating” hip bone due to sexual selection? They have not been lost over evolutionary time as would be expected vestigial of bones serving no function so…have they remained to serve some function? Indeed they have believe scientists at the University of Southern California and the Natural History Museum of Los Angeles County.
The cetacean pelvic bones (Image: Wikipedia user Andrew Z. Colvin)
Dines et. al. published their research in Evolution. Through analysis of cetacean pelvic bones they have determined that cetaceans with relatively large testes also have relatively large pelvic bones irrespective of their overall body size. The size and shape of cetacean pelvic bones are evolutionary correlated to relative testes mass. However, their rib bones (used as a control anatomical feature) have not increased in size alongside the pelvic bone increase therefore it is not just a complete bone size increase but a specific correlated increase.
What could be the reason for this?
Firstly large testes are linked to promiscuous species because bigger testes means more sperm which, means greater mating potential and subsequent offspring. More offspring mean that their sexual advantages (large muscles and large testes) are passed on.
A further hypothesis is that the large pelvic bones could provide a mechanism for the enhanced manoeuvrability of relatively large penises by providing a greater surface area for muscles to attach to! These muscles are called the ischiocavernosus and enable enhanced manoeuvrability of the penis from side to side and may also enable the maintenance of an erection. In female cetaceans these muscles insert into the clitoris leading the scientist to speculate that it could be possible that clitoral movements play a role in female mate choice, potentially meaning the female pelvic bone is also subject to sexual selection.
Courtship between a male and female beluga whale. (Photo : Flickr: Brian Gratwicke)
So in essence the large pelvic bones could have been sexually selected for to be larger to support larger muscles and therefore larger male penises in cetacean (with more manoeuvrability…?). Could this be for the pleasure of female cetaceans or is that all being spun around to create media excitement? I guess since we can’t yet ask female cetaceans we shall just have to keep speculating and researching. It would be pretty interesting if these highly social species have sexually selected for highly manoeuvrable penises to please and entice female cetaceans into copulation.
What we do know is that this is probably the first time that scientist have shown sexual selection affecting the internal anatomy that controls the male genitalia of a species.
What do you do? I am asked that a lot. Also, what have you been up to recently with all that travelling? I do a lot of different things and everyone thinks I have the most crazy amazing career (and you know, I do!).
It can sound glamorous but what I spend a lot of time doing is just sitting or standing on a boat, eating a delicious combination of; trail mix, crackers, chocolate, and fruit, waiting……
For whales to breathe!
It is an amazing, but by no means easy way to spend your time. I do however love nearly every minute of it. There are crazy days of high winds and big swells. White caps so severe that you would be lucky to spot a whale blow! On a good day it is the most wonderful place in the world to be, a light breeze in your hair as you scan the horizon waiting for that unusual movement to catch your eye. The whale blow, its massive exhalation of breath.
Blowing killer whale from the A36 brothers in Johnstone Strait, BC.