While aboard the Passing Cloud in Matheson Inlet Tansy was alarmed to see a reef coming up under the bow and braced for a collision.
Once it came into focus, it turned out to be something far less dangerous to the Passing Cloud than a reef and much more interesting.
It was an aggregation of thousands of moon jellies, a kind of invertebrate in the genus Aurelia.
As it happens the father of Tansy’s Favourite Photographer is an expert on jellies. He tells her that this swarming behaviour is not well understood though is of much interest to biologists. It does seem to occur in part because of their behaviour – responses to the environment can lead to these aggregations. In the case of Aurelia it might enhance reproductive success. With other jellies there may be other explanations related to what is good for both the jellies and symbiotic algae that live in their gut. In any case, these swarms are also of interest as they might sometimes relate to climate change. And they can have economic and environmental consequences when they get sucked into the intakes for power plant cooling systems, as happened to numerous nuclear power plants and even a nuclear powered aircraft carrier. You can read more about these stories at this link.
Tansy was oblivious to these worrying stories as she hung over the ship’s rail, mesmerised by the slow pulsing of the jellies just beneath the surface. She wished for Hitty-sized snorkeling gear, especially a weight belt, to have a closer look from beneath the surface.
Fortunately, the first mate Liam put a video camera into the water to film them and so Tansy can watch his video months and years later, as can you too: