Oceanic Dolphins (Family Delphinidae)

Originally this post was going to be about the Pacific white sided dolphin; these are the kind kept at the Vancouver aquarium, and thus the ones I’m most familiar with. After doing a bit of research into the species, I came across some amazing facts from other kinds of dolphins, and I just couldn’t help but share them.

The basic bullet point about dolphins is that they are probably the coolest mammals out there. Their level of intelligence and cooperation is mind boggling. Douglas Adams wasn’t far of when he said dolphins were the second most intelligent animals on earth (above humans and below mice).

Oceanic dolphins are members of the family Delphinidae, which includes all ocean dwelling dolphins (as opposed to river dolphins), killer whales and other false whales. Most dolphins share the same general properties: they are streamlined for efficient swimming in water, have powerful tail fins for propulsion, dorsal fins for stability and pectoral fins for directional control. All dolphins have the ability to echolocate, which they use to find their way in murky waters and to locate predators and prey.

The most fascinating part about dolphins is, of course, their intelligence. There are so many examples of dolphin intelligence I don’t think I could possibly cover them all in one post, but I will try and highlight some of the best ones.

First up: social organization. Dolphins are amazing at this. Most species live in groups of 50 or so individuals, although when feeding conditions are right groups can get incredibly large. With that many animals in one place, communication is a must. To this end, dolphins have developed a highly sophisticated repertoire of vocalizations, mainly involving clicks and whistles. Each dolphin has a signature whistle that they respond to, and will call their own whistle as well as other dolphins’, who then respond to that call. Basically, dolphins have names, which I find incredible. There has also been evidence that dolphins might be able to listen in on another dolphin’s echolocation – so if a dolphin was inspecting a object with sound, another dolphin could listen in and gather information about that object, without actively echolocating itself.

A superpod of dolphins - these can be as many as 100,000 individuals

A superpod of dolphins – these can be as many as 100,000 individuals

Dolphins tend to form strong social bonds; although the pods they live in are fairly fluid (dolphins come and go as they please), they are often seen help injured or ill members of the pod. They will stay with the sick dolphin, even swimming beneath it and pushing it to the surface to let the animal breathe. Other times dolphins help those not of their kind. A bottlenose dolphin named Moko was found helping two beached pygmy sperm whales. The dolphin swam into the shallows and guided the two whales through a narrow channel back to sea. Other reports note that dolphins have protected swimmers and divers from sharks, circling around the humans and driving the sharks away with their tough rostrums (beaks).

Secondly: play. Dolphins are well known for their tendency for showy antics, which may just be a form of play. They will jump and do flips and spins like you might see at a dolphin show, even in the wild. Some people have theorized that these might help the animals locate schools of fish, or be a form of communication. Personally I think they are just for fun; who doesn’t like leaping through the air every once in a while. They also love to surf in waves, especially those of boats, and are often seen cavorting beside boats, leaping in the air in time with the waves. There have also been reports of dolphins playing in captivity, by creating bubble rings and then either examining the bubbles with echolocation or swimming in and bursting the bubbles with their mouths.

A dolphin creating a bubble ring – a form of play often seen in captive dolphins

Third and probably the most impressive: general intelligence. Dolphins have exhibited a number of high level cognitive abilities. They have shown some evidence of problem-solving, but this may be a form of mimicry, as dolphins are extremely good mimics. One study demonstrated that dolphins can produce creative behaviour. The study involved only rewarding dolphins for novel behaviour. The researchers picked a behaviour and rewarded the dolphin every time it exhibited it for one day. The next day, the dolphin would preform that same behaviour, but the trainers would only reward the animal for a different behaviour (all behaviours at this time were ones currently learned by the animal). This continued for almost two weeks, until the dolphin ran out of behaviours that it knew. The dolphin then began repeating behaviours, but these were not rewarded and the animal became despondent. Sixteen days later, however, the dolphin showed a flip they had never seen before. Once they reward the new flip, the dolphin went crazy. Instead of repeating the flip, as you might expect, the animal seemed to understand that it wasn’t being rewarded for any particular behaviour, but instead for the performance of new ones. So the dolphin did a tail swipe the trainers had never seen, then a whole list of new behaviours, so quickly that the trainers couldn’t keep up with the rewards.

It’s interesting to note that a similar experiment was conducted with humans, and once the subjects figured out the point of the experiment, they experienced relief, instead of the flurry of novel behaviours and excitement that dolphins demonstrated. I don’t know what this says about people or dolphins (if anything), but I think it’s still kind of cool.

Tool use by a dolphin - the sponge protects the rostrum from abrasions while the dolphin hunts

Tool use by a dolphin – the sponge protects the rostrum from abrasions while the dolphin hunts

Dolphins have shown evidence of awareness of the future; dolphins in an aquarium in Mississippi have been trained to bring trash to their tank cleaners to help keep the aquarium clean. One dolphin has figured out that if she hides all the garbage under a rock and brings it to the trainer one piece at a time, she will get more fish. Other impressive displays of intelligence involve tool use by dolphins. Bottlenose dolphins have been observed wrapping sponges around their beaks while hunting for food on the sea floor, to protect them from scratches. Another report has dolphins cooperating with fishermen in Brazil. Dolphins herd fish towards the shore where the men wait with nets; at the dolphins’ signal the men cast their nets and any fish that escape are easy pickings for the hungry animals.

I could go on and on about dolphins – I can think of three things off the top of my head I wanted to mention but this is already my longest post, and I don’t want to bore anybody. I’ve always known dolphins were smart, and growing up there were my favourite animal, but I never realized just how many amazing things they do until this post. I think I’ll go try and find a book on dolphin behaviour now.

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3 thoughts on “Oceanic Dolphins (Family Delphinidae)

  1. Oh, 8 year old me would be so happy to read this! I also love that they use leaves and other floating debris as toys, carrying them around until they get bored with them. Crazy awesome animals!

  2. Pingback: Cookiecutter Shark (Isistius brasiliensis) | Our Wild World

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