Streaking, Acrobatics, and Organised Debauchery: Just Another Day For a Striped Dolphin!

The grey bottlenose may steal the limelight, but the striped dolphin has some tricks and kinks of its own. In more ways than one.

Signature move

It always has a blue-black side stripe and back blaze, but otherwise its body pattern is as different as a human face and accent. As well as chasing ships to ride their bow waves, and “breaching” in the air up to 3 times its length, this oceanic dolphin brings its own move to the party too: “roto-tailing”, or twirling its tail in mid-air.

It’s entertained many a sailor in temperate and tropical seas, and in the eastern Pacific it’s sometimes known as the “streaker”. Before you start pointing and laughing, that’s after its speedy getaway, and not for reasons of public nudity. No, it’s for much darker and depressing ones.

In deep water

Every year there are drive and hand-harpoon dolphin hunts in Japan – with casualties up to 21,000 – after which the captured dolphins are killed for meat or sold to aquariums. So you can’t blame it for making a swift retreat at up to 37kph (23mph). Being tangled in tuna nets also adds to the fun, especially when it can “only” hold its breath for 10 minutes.

Not all dangers are obvious, though. In the Mediterranean in the 1990s, likely due to pollution, a group of striped dolphins fell victim to a measles-like infection, stranding themselves before dying. If this wasn’t awful enough, as intelligent and social animals they can be hit hard by the loss of a comrade.

And I thought colouring outside the lines was bad.

Sad song

For instance, in 2016, a male striped dolphin was found circling and nudging his dead female companion for over an hour. Since staring at the body seemed way more important than predators or boats of curious humans, he may have been grieving.

Well this post took an extremely dark dive. Fortunately it’s not the type usually made by the striped dolphin, when it plunges as deep as 700m (2,296 ft) into the “twilight” zone to cram its gullet with fish and squid. But let’s get back up to the sunlight zone where there’s more chance of help, hope, and the aforementioned dolphin debauchery. Because that’s why you really clicked on this post, wasn’t it?

While it’s true that humans and nature can suck in various ways, all isn’t lost, because the striped dolphin is protected in most areas, and with a relatively healthy population of 2 million, is Least Concern on the IUCN Red List. It would be a different story without said protection, but it’s enthusiastic about keeping its numbers up.

Emotion of the ocean

Gathering in hundreds during the mating season, the striped dolphin sensibly organises into mixed (adult and baby), juvenile, and adult schools, with the latter splitting into “breeding” and “non-breeding” groups so everyone knows where the party is. For said partygoers it’s pretty much a free-for-all, although some females have favourites, and once they’ve all enjoyed some male company, the males leave. About a year later, it suddenly becomes a mixed school!

The calf stays with Mum until weaning at 16 months, moving to a juvenile group soon after. As for Mum, she takes another 3 years off before plunging back into the dating game. And the pool is much bigger than at first glance.

We’ve recently discovered that the Clymene or “short-beaked spinner” dolphin may be a natural hybrid, descended from striped and spinner dolphins rolling with each other as much as the waves.

So humans aren’t the only other species impressed by their acrobatics! It’s also nice to know that for a dolphin, casting a wider net isn’t always a bad thing.

TLDR

LatinStenella coeruleoalba, after its blue and white stripes

What? Clue’s in the name, but it’s a dolphin with blue and white stripes

Where? Warm and temperate waters worldwide. It’s also the most abundant cetacean in the Mediterranean.

How big? Males up to 2.6 m / 8.5 ft long, females 2.4 m / 7.5 ft long

Endangered? Currently Least Concern, as there are about 2 million worldwide. At the same time, it’s considered “conservation dependent”, so without any protection in place it would be at risk, especially from tuna nets, dolphin hunts, and pollution.

Probable motto: I’m having so much fun, I want other species to join in!

They look cute. Do they need my help at all?

Pollution, net entanglement and hunting are the main sources of un-fun for a striped dolphin.

The Blue World Institute looks out for its interests in the Mediterranean and Adriatic seas, and the Whale and Dolphin Conservation Society is campaigning to end the dolphin hunts in Japan.

Just to prove I’m not fibbing:

Choi, Charles Q. 2014. “DNA discovery reveals surprising dolphin origins“. National Geographic.

Daley, Jason. 2018. “Study suggests dolphins and some whales grieve their dead“. Smithsonian.com.

Moreno, Ignacio B. et al. 2005. “Distribution and habitat characteristics of dolphins of the genus Stenella (Cetacea: Delphinidae) in the southwest Atlantic Ocean“. Marine Ecology Progress Series 300:229-240.

Morrell, Virginia. 2018. “Do dolphins feel grief?” Science.

Savage, Melissa. No date. “Stenella coeruleoalba“. Animal Diversity Web.

Stenella coeruleoalba“. No date. ASCOBANS.

Stenella coeruleoalba“. No date. IUCN Red List of Threatened Species.

Stenella coeruleoalba (Meyen, 1833)”. No date. Food and Agriculture Organization of the United Nations.

Striped dolphin”. No date. Cetacean Research and Rescue Unit.

Striped dolphin“. No date. Hebridean Whale & Dolphin Trust.

Striped dolphin“. No date. National Oceanic and Atmospheric Administration.

Striped dolphin“. No date. Whale and Dolphin Conservation Society.

Striped Dolphins, Stenella coeruleoalba”. No date. MarineBio.

Featured image credit: “Dolphin while jumping in the deep blue sea at sunset” by Andrea Izzotti

 

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