In the United States, Iguanas have been falling from trees for the opposite reason. It’s too cold! Florida, which is used to tropical heat all year round, has seen temperatures fall to near freezing and suddenly the green lizards have been tumbling from the trees left and right.
The good news is they aren’t dead – at least not all of them. Shocked by the cold, they freeze – figuratively speaking. It’s not a new phenomenon and once the temperatures rise again, the more cold-resistant among them will come back to life. Ironically this process of natural selection makes iguanas, initially an invasive species in Florida, increasingly capable of surviving in colder climates so we shouldn’t be surprised if they gradually start to show up further north than sunny Florida.
Iguanas in Florida weren’t the only ones caught off-guard by the recent sudden drop in temperatures in the eastern United States. But not all creatures fared as well as the green lizards. During the “bomb cyclone” that hit the northeastern states, frozen sharks suddenly started to wash up on Cape Cod in Massachusetts. And yes, they were literally frozen and very much dead.
Thresher sharks, which is the species in question, can go some way to retaining their metabolic heat, enabling them to survive in colder water for longer than many other sharks. This character trait, which would usually be seen as an advantage over other species may have been the cause of death in this case. Since they can cope with lower temperatures better than other sharks, threshers tend to stay in the coastal waters of Maine until late December long after other species such as makos or blue sharks have left for warmer climes.
While the cause of death is still entirely speculative, scientists suspect the thresher sharks were surprised by the sudden drop in temperature and as they scrambled to get south quickly, they may have beached, or they simply died of hypothermia.