| ▲ | princeofwhales 3 days ago | |
It may be that whales are using their song not just as inter-species communication, but as a farming method for their desired food. Could it be a "lullaby" to the krill? Or a signal which causes the krill to group closer together, thereby increasing the efficiency of the whales' feeding activities? Many bat species use ultrasonic pulses to detect moths and other flying insects while hunting, so whalesong may even be some form of longer range food detecting sonar? I'm not sure if that amount of distributed biomass would be detectable, but we don't know enough about their sensing apparatus to completely rule it out. Interestingly, some moth species have learned to jam the signal sent by bats by emmiting loud clicks, disrupting the return signal to throw off their target triangulation ability. I don't think the krill are so equipped, unfortunately for them! My guess is if their (whale) numbers were higher, they wouldn't consume their preferred food source in an unsustainable manner, giving the krill time to recover and moving on to larger patches to allow the recently "grazed" areas time to recover. One thing is for sure, their song activity is at least partly related to their feeding and migration activity in some way: https://www.upi.com/Science_News/2020/10/01/Blue-whale-singi... Also, studies have found that whalesong differs in frequency range depending on where in the world they are, possibly relating to water temperature and overall salinity/acidity, as colder/warmer and alkaline/acidic water will have different sonic properties due to density changes in the transmission medium, or the increase in ocean activity from shipping and ULF emmissions from submarines, and the overall effect of sea surface temperatures increasing. Blue Whales for example are known to feed at relatively shallow depths (<200m) as that's where the krill gather during the daytime. The interesting thing is there is an overall downward trend in the sonic frequency observed in the last several decades: https://www.encyclopedie-environnement.org/en/zoom/decline-f... & https://www.theatlantic.com/magazine/archive/2019/10/whale-s... The recent articles in the press regarding the decline of Blue Whales' song in the pacific seems to point to the fact that they signal for abundance of their food source after locating it, like ringing a dinner bell when it's feeding time. This along with other factors like simply conserving their energy for further search activity could explain the increasingly infrequent song activity. With their population still recovering as a result of industrial whaling (global estimates are ~10,000-15,000), perhaps this behaviour is emergent, like a social call to help other whales feed, boosting their long term chances of survival in the changing ocean environment: https://www.nationalgeographic.com/animals/article/ocean-hea... Finally, I spotted this interesting looking project regarding whale communication if you're interested (unsure how active it is currently): | ||