Cetacean Society International

Working for whales, dolphins and porpoises worldwide

CSI Photo Gallery

Atlantic White-sided Dolphins

(Lagenorhynchus acutus)

This Atlantic white-sided dolphin is surfacing to breathe. All cetaceans must do this, even in hurricanes and high waves. What must it be like to know that you have to surface no matter how stormy and dangerous the weather is? Babies have to breathe more often than adults, and the danger is that they will be separated from their mothers.
This Atlantic white-sided dolphin is jumping in play, giving us a chance to see his beautiful color pattern. How strong his tail flukes must be to push his 400 pound weight eight feet into the air! Can you see how the powerful muscles are designed for up and down movements? His tail stock is very thin vertically for streamlining.
The color patterns of dolphins may allow to them to hunt cooperatively or maneuver in groups without hitting each other, and certainly help tell species apart. There are very few visual sexual differences, but the dolphins seem to know easily enough. Body language is important for visual communication.
Is this very slowly swimming Atlantic white-sided dolphin asleep? We think that cetaceans "sleep" with only one half of their brain at one time, and possibly with only one eye open. They are voluntary breathers. If they slept as we do, and didn't consciously take a breath, they would suffocate. Their bodies are so streamlined that they move with little effort.
One primary rule a social dolphin like this Atlantic white-sided must live by is to never be left behind by the group. In the dark, noisy, even stormy sea this may be very difficult to do. Social groups are better for catching food, defending against predators, and raising young.
White-sided dolphins often play like this, but they may have other reasons for leaping clear of the water. Perhaps they want to look around, or make noisy splashes that send a signal to others, or even escape. When the female dolphin reenters the water she can swim quickly in any direction. The male just behind her won't know which way she's gone.
Around sunset on this day many dolphins in this group breached, some facing the sun. Why? Part of our human problem is that we always want to know why things happen, and if we can't know we might make up reasons. So some people might think the dolphins were watching the sunset, and other people would laugh, but no one really knows. We are far too ignorant of dolphins' lives to understand much, but it's important to keep trying.