Dolphin lullabies and noisy whales

I'm going to stick with underwater singers, with a couple of quick stories from the world of marine mammals.

Firstly, we have those playful creatures, the bottlenose dolphins, and news this week that as well as using squeaks and whistles to hunt for food and communicate within the social pods they live in, dolphin mothers may also sing special lullabies to their babies for the first few weeks after they are born.

Researchers from Dallas Zoo in the US think that the captive female bottlenoses are singing to imprint their offspring so they recognise their mothers and don't get lost, or worse, stolen by another females in the pod - something that can happen in the first day or so after birth, but doesn't seem to happen much after that, hinting that once a young dolphin has learned who its mother is, it won't wander off with anyone else.

Then, there is also news of the noise-making talents of another ocean inhabitant, the magnificent humpback whale. It seems that it is not just their alluring songs that are deep and meaningful, but other noises they make, like splashes, bubbles and grunts too, may also hold important information..Researchers from the University of Queensland have been studying various noises made by humpback whales and the corresponding behaviours as they migrate along the Great Barrier Reef and down to the Antarctic each year.

And they found that the whales seem to make particular noises in certain social occasions. So for example, the noise of leaping into the air and splashing back down - known as breaching - seems to happen most often in groups with just one adult, who might be saying to the youngsters "Here I am!"

This study has not only opened up the possibility of more complex whale-to-whale communications, it also highlights the importance of understanding how whales use sound and how all the noise pollution we pump into the oceans might be affecting them.