On Tuesday I had the pleasure of attending a harbour porpoise postmortem at London Zoo. Not everybody’s idea of an exciting day out I realise, but it was for me. Apart from the cold that is. I was absolutely frozen in the pathology room, with the door wide open to reduce corpse smells, and me not layered up for the outdoors when I’d expected to be indoors. So through my trembling, teeth chattering frozeness, I watched and learnt.
The purpose of these postmortems is to find out what the animals (whales, dolphins, porpoises and turtles) died of – disease, toxins/plastics in the marine environment, as by-catch in fishing nets, eating too much marine litter, wounded by marine vessels, starvation, etc.. This information is then used to hopefully improve the state of our seas, change policy, change fishing methods, and many more objectives.
Rob, our pathologist, talked us through all the body parts and what he was looking for. He also took lots of tissue samples which are studied for bacteria, virus, and toxins, and sent off to all sorts of partner research projects.
This little lady was found in Essex, stranded and dead. Though she may have stranded alive and subsequently died. She was actually rather long, longer than the average porpoise length, though extremely skinny. You can see in the photo that she’s almost concave. No healthy cetacean should ever be concave on any part of their body.
After stranding, and dead, opportunistic birds will give it a good peck to get at the meat.
The picture on the left shows her belly button. The picture on the right shows her private parts. The two slits either side house her teats. They are hidden away making her more hydrodynamic. When a baby porpoise is born, it has a hairy tongue which improves suction and grip in an otherwise slippery wet environment.
Beneath that dark skin should be a thick layer of blubber. This skinny lady’s was rather thin. Too thin to keep her warm in cold winter waters. Rob then peeled back the skin and blubber to reveal the muscle tissue beneath. darker than our muscle tissue, due to the tissue’s ability to hold high levels of oxygen. An animal such as a sperm whale, that can dive and therefore hold its breath for over an hour, has muscle tissue that is nearly black. The more oxygen there is, the darker the tissue.
The pathology tools were quite amusing. Here Rob cuts away the rib cage to get at the organs – with a lopper!
The intestines, put aside for later.
Rob shows us one of her little ovaries. Like humans, porpoises have two ovaries, though they only ever use the left one. A pathologist can estimate a porpoises age by her ovary. Each little bump signifies one year after she has become sexually mature. We guessed she was 19/20 years old. Quite old for a porpoise.
The lungs, liver and kidneys (and heart) all looked rather healthy.
Harbour porpoises have three stomachs. We got to see inside each one. They all had very different linings. This was the first stomach, and it appeared to be bursting full of worms/parasites. However we were assured that this was actually a light load, and would not have affected the animal’s lifestyle. The second and third stomachs had no parasites. And not one of the three had a trace of food. She had not eaten in a while. There were also no parasites in the intestines, the domain of tapeworm.
Having disposed of the body, Rob moved on to the head. When he got the saw out, we all stepped back!
The ear bones and the brain. The large brain.
We also got to see the monkey lips, the inner workings of the echo-location.
All extremely fascinating, and suprisingly not queasy making. Did it smell? Only a tad.