Marine Creature of the Month Famous Fish May '20

Marine Creature of the Month

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Common Bottlenose Dolphin

Our famous fish this month won by a landslide - sorry Squiddy. So let's dive a little deeper and take a look at Flipper!

Kingdom: Animalia

Class: Mammalia

Conservation Status: Least Concern (LE)

Picture from Pinterest

WHAT IS FLIPPER?

Flipper is a dolphin. He is the most dolphin-y dolphin you can get. And I think that is largely down to having a television presence since the sixties! All dolphins are mammals, meaning they breath air and give birth to live pups - and bottlenoses are no exception. Despite having a nose-like snout, they have a blow hole on the top of their head, which is used for breathing.

Common bottlenose dolphins are grey and bear all the body features we expect from dolphins. Flippers, check. Dorsal fin, check. Adorable face, double check. They grow between 2 and 4m (6.6 and 13.1ft) and can weigh as much as 650kg (1,340lbs)! For some context, I would say I am the very average weight of 77kg (169lbs), so a dolphin can weigh up to nearly ten mes! I find this very surprising, for such a streamlined and relatively small creature to be so heavy.

As with many mammalian species, dolphins show sexual dimorphism - meaning there is a difference in appearance between the males and females. It is the males which tend to be bigger and heavier. But that is the only real difference in appearance, the males aren't darker or striped or anything else like that. Something both males and females do have is flexible necks. This is due to five of their seven vertebrae not being fused. This is not common across dolphin species, found only in bottlenoses.

It is a well known fact that dolphins are incredibly intelligent. The common bottlenose's brain is bigger than a human's. (Honestly, is that surprising? Look at our political leaders right now!) They have demonstrated the ability to self-recognise, which is not common in animals. Who else has put their dog in front of a mirror and laughed at their reaction? They can also use artificial language, categorise objects, and have a great capacity to be trained. It's because of this intelligence that they feature so much in our entertainment industry. Dolphin shows at aquariums, movie parts, swimming with dolphin experiences... They have even been known to co-operate with fishermen, driving fish into their nets and catching the escapees.

HOW DOES FLIPPER LIVE?

Common bottlenose dolphins are found worldwide, with the exception of polar waters. They prefer temperate and tropical waters to the icy polar regions. They can be found across the globe. However, until recently, they were considered a single species, but further study has shown genetic differences. Two species have been split from the common bottlenose, with potential for more, and "bottlenose" has become an umbrella term for the genus.

They live in either offshore or inshore populations. The offshore populations tend to be larger and darker, living in a bigger space and deeper part of the ocean. They also migrate further than inshore populations – again, more space to do so! – travelling up to 4,200km (2,600miles). Being larger means they are more suited to deeper dives and are better protected against predators, as well as being able to retain heat. The smaller inshore populations are better adapted for living in warm and shallow waters, being nimble and able to disperse heat.

In the wild, bottlenoses can live up to between 40-50 years old although in the wild they average around 17 years old. Whether this is down to predation or human interaction, I cannot say. In captivity they have been seen to reach 51 years of age. Males mature somewhere between the age of 8 and 13, while females mature at a younger age, between 5 and 10. “Courting” involves an alliance of male dolphins separating a female from her home range, mostly in the spring but also at any time of the year. It is a polygamous affair. Females gestate for a year and give birth to a pup about 1m (3.3ft) long.

Dolphins are social creatures. They live in pods. Pod sizes vary, depending on location and population needs. Nursery group sizes would differ to those of adult males – the former being larger to protect the young. They have developed effective communications (and even regional accents, according to Qi). They can emit squeaks through their blow holes and whistle through the nasal sacs below. In rather fabulous displays, they can also communicate by slapping and breaching the water, and even have developed their own body language. All of this is giving me serious So Long and Thanks for all the Fish vibes!

Picture from Oceana

WHAT DOES FLIPPER EAT?

The answer to this is: a lot. Most people would answer with tuna – due to their association “dolphin safe” tuna. But they also eat squid, eels, shrimp, and other fish. Whole. Yeah, you read that right. They eat their food whole. Anyone else gagging at the thought of eating an eel whole? You’d be able to feel it all the way down!

Their diets largely depend on where they live. Populations on the US Atlantic coast will eat Atlantic croakers while those living near to South Africa will eat olive grunters. Eat what’s available – simple really. 

Being intelligent creatures, they have some nifty hunting methods. In groups, they harvest schools of fish. Individually, they use echolocation to hunt down and find their prey. It’s not quite up to orca standards of inventive hunting, but it’s still pretty clever. 

 

WHAT THREATENS FLIPPER? 

On the whole, common bottlenose dolphins are not threatened. Their conservation status is Least Concern which means their populations are abundant and stable. However, the human fascination with dolphins does come with its problems. There are many groups which protest their captivity, highlighting it to be cruel and inhumane to keep such intelligent creatures in small spaces. They are also migratory creatures and are denied the natural instinct to travel.

As with many larger marine creatures, they fall victim to bycatch and ghost fishing.  Famously, this occurs with tuna fishing which has led to the “dolphin safe” branding on tuna packaging. But, as with all my MCotM, the main threat to their lives is pollution. And I don’t just mean the vast quantities of plastic floating in our oceans either.

Coastal populations are affected by human populations affect the water quality. Agriculture and changing water drainage increases the ammonia in the water, which fuels the growth of algae. This creates a massive imbalance in the ecosystem. Some species thrive but many more are starved as the algae suffocates other food sources. Being the apex predator of coastal ecosystems, this has a knock on effect on the dolphins too. The fish which have been feeding on the excessive and harmful algae often become toxic as a result, which is then passed onto the dolphins. It causes respiratory and neurological problems, often resulting in death.

Plus, many diseases found in bottlenose dolphins have been linked back to the water quality. Oil spills occur in areas which are vital to dolphins – for calving, feeding, and foraging. Not only does it massively damage their environment, it has an effect on their health too. Oil spills have been connected to lung and reproductive diseases in female dolphins. This is having a long term effect on their ability to reproduce and the calves which are born. There has been a drastic decline in successful pregnancies in certain populations of bottlenose dolphins and it is believed to be directly related to oil spills.

 

Picture from NPR

FUN FACTS

• They are referred to as common bottlenose dolphins or Atlantic bottlenose dolphins.
• It is the largest species of beaked dolphin.
• But not the largest species of dolphin, we know that to be orcas!
• Their "bottlenose" name comes from the resemblance of their snout to old gin bottles.
• Dolphins are so intelligent that they can be trained to locate sea mines for the navy.
• There is a solitary male dolphin living in Dingle harbour, Ireland, called Fungie. Having been there since 1983, it is believed to be more than one dolphin which has become a symbol of the town.

 

Picture from WWF

I hope you enjoyed finding out about Flipper. Sorry it got a little dark towards the end there, but that’s humanity for you! Well, that’s the agriculture and fuel industry for you, maybe. The demand for more, more, more is affecting the balance of our planet and definitely needs to be addressed.

Anyway, before I rant further. Do you know any fun facts about bottlenose dolphins? Which is better: Flipper (1963) or Flipper (1996)? Lemme know below!

And to end on something fun, So Long and Thanks for all the Fish!

Listening to: This is Norah Jones (Although, honestly, my internet had a fit while writing this, so it was just The Long Way Home on repeat! Good job I like the song.)