I was out on a boat today in the ocean and saw a gray whale breach up close (incredible!) and a pod of dolphins jumping in and out of the water. Why do they do that? Is it just for sport or do they do this for some practical reason?
Well, dolphins gotta breathe so I guess jumping lets them do that while keeping their speed up. Also I imagine it is fun! I’m sure there’s much more to it than that though, particularly for whales breaching.
Regarding whales it seems there are several theories but nothing concrete.
Some of it is part of the process of gathering food. I’m guessing that some part of it is just curiosity about and communication with humans (or just the boats we use). I wonder how much of this has been observed when they don’t know we’re around. Maybe they wonder why we air dwellers dive in the water sometimes.
I think sometimes it’s just for fun. But I think sometimes it serves a purpose. I’ve heard that when dolphins are chasing fish to eat, they jump in and out of the water because it confuses the fish. The fish can’t track the dolphin’s movements the way they would be able to track a normal underwater predator and it makes it harder for the fish to successfully escape. Flying fish use the same mechanism in reverse to escape predators.
My question is why when whales do it it’s breaching and when dolphins do it it’s plain old jumping.
They’re different things. Dolphins jump at a low angle and spear back onto the water similarly. It’s an action that blends with rapid forward motion seamlessly. Whales breach by jumping near vertically and then just crashing back into the water
They have as much in common as - in human swimmer terms - a racing dive and a bomb dive.
Having studied whales in the wild, as well as trained dolphins in captivity, I can tell you that dolphins will sometimes breach on their own just like baleen whales. They of course will jump out of water on their own too. These are both natural behaviors. I’ve seem a large pod of common dolphins off the coast of Mexico pass by my ship and many were jumping out of the water to get a good look at us… at least that what it looked like to me.
As far as why they do these behaviors we can only guess. Breaching makes a loud sound and can presumably be used to communicate your general location from a distance. It also may be a way for them to scratch themselves and remove annoying parasites. I think it’s reasonable to surmise that they also do it just for fun too.
Dolphins also breach. I used to work at the Shedd Aquarium in Chicago (not as a marine biologist) and the dolphins would breach all the time. On queue from their trainers, usually, but it’s natural behavior for them.
The educational materials said that no body knows exactly why wales and dolphins breach, but there are probably a number of reasons - for fun; to get a view above the surface; to dislodge parasites or scratch an itch; to communicate with others in the pod…
Dolphins also jump through the air; this is partly because they have to surface to breathe anyway. I also wonder if porpoising through the air isn’t faster than swimming just through the water because of the reduced drag.
Wouldn’t their eyes have an analogous issue to human eyes underwater? (That the refractive index of air isn’t what their eyes are adapted to, and therefore their lenses won’t properly focus an image on the retina.)
The imprisoned dolphins and whales at Marineworld seem to see pretty well out of the water. As a kid I was pretty comfortable with my eyes open in pools and clear enough fresh and salt water, I could find coins in a pool and crabs on bottom of the ocean, I couldn’t tell what kind of coin easily but I could catch a crab if I could keep up with it. Just depends on how good a look they expect, but if they can see and recognize a boat from underneath they may want to find out what the part out of the water looks like even if it’s not as clear of an image.