Water on Earth

Earth would not be Earth without water, but have you ever wondered about the records that lie behind our blue planet?

Here, we take the plunge into the watery composition of our world and also turn the spotlight on some of record-breaking creatures that inhabit our oceans.

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A world of colours

Blue is the colour that guarantees our survival.

Magnificent oceans, flowing rivers, rain and snow falling from the sky - water is a treasure we experience (and sometimes abuse) every day.

Taking many different forms, it exists in our lives, in our blood, and in the air we breathe.

Our own body is majorly composed by water (a staggering 60% of our body and 90% of our blood) pivoting around a tiny but life-changing chemical formula: H2O. You might be surprised to hear that most freshwater, however, is locked away under the Earth's surface or exists in non-liquid forms.

In fact, more than two-thirds of freshwater available on our planet are frozen in ice caps and glaciers.

The largest one is the the Antarctic Ice Sheet, extending 13,924,000 square kilometres (5,376,100 square miles), including its floating sections (known as ice shelves).

That is almost 1.5 times the size of the entire USA.

Far from being barren, these breathtaking frozen lands host plenty of life forms and, as well as being home to flourishing biodiversity, they also regulate the overall temperature of Earth.

Acting as a mirror and effectively reflecting the Sun's rays, vast expanses of ice have stabilized Earth’s climate for millennia, absorbing solar heat energy and reflecting light back into space.

“The more area covered by ice, the more heat reflected to space,” writes NASA.

Overall, oceans comprise the vast majority of habitable space on the planet.

Impressive in its immensity, the crown for the largest ocean in the world goes to the Pacific: it covers a surface that measures over 16 times the size of the USA, and represents almost half of all ocean across the world.

A gargantuan size that inspired awe in many an adventurer, especially when measured against the smallest ocean on the planet, the Arctic. Covered in ice for the vast majority of the year (though this is changing in the last few decades) and home to a wealth of marine fauna, this frozen kingdom exists on a delicate environmental balance and spans for "only" 6.1 million square miles.

With an average depth of 3,953 feet (1,205 m), it's also the shallowest ocean.

Another outstanding body of water is the largest of the Earth’s seas: often a cause of political friction, the South China Sea measures a total of 3,500,000 square kilometres (1,400,000 square miles) and embraces several countries - from China to the Philippines and Indonesia, but also Malaysia, Brunei, Singapore and Vietnam.

Water on earth

A matter of…scale(s)!

In this year's GWR 2024 book, we turn the spotlight on some of the biggest animals that live in the ocean.

Have you ever wondered what’s the world’s largest fish?

With its outstanding size and immediately recognizable features, the largest fish living in our oceans today is the whale shark (Rhincodon typus).

Despite its daunting name, this giant of the sea is known to be shy (like many other mega-sized marine animals) and it can grow to be very old – although only 10% of the total whale sharks population is estimated survive to adulthood, the ones who do can live for 150 years!

They are normally found in the warmer areas of the Atlantic, Pacific and Indian oceans.

Often referred to as “gentle giants,” these shy but majestic animals are filter eaters, meaning that they can’t bite.

Armed with tiny teeth, they can process over 6,000 litres of water an hour but their diet is limited to small shrimp, fish and plankton by using their gill rakers as a suction filter.

These elusive fish can migrate for long distances, and their size can vary drastically depending on their region, age and sex.

However, those measured to date have averaged 4–12 metres (13 feet 1 inch–39 feet 4 inches) long.

The largest scientifically documented specimen is a female whale shark that was caught in the Arabian Sea off Veraval in Gujarat, India, on 8 May 2001; she measured 18.8 metres (61 feet 8 inches).

Although a regular whale shark is impressive in size, it’s not the overall largest animal that roams the seas.

That title goes to the blue whale (Balaenoptera musculus).

The average specimen of blue whale measures around 20–30 metres (65–100 feet) and weighs c. 160 tonnes (176 tons), and it can reach a maximum confirmed length of 33.57 metres (110 feet 1 inch).

Having inspired stories, folklore and adventure novels throughout history (such as Herman Melville’s classic Moby Dick), these majestic animals have kindled the fantasy of humankind for ages and even larger historical specimens have been recorded by both length and weight.

The average specimen of blue whale measures around 20–30 metres (65–100 feet) and weighs c. 160 tonnes (176 tons), and it can reach a maximum confirmed length of 33.57 metres (110 feet 1 inch).

The heaviest blue whale overall, and the heaviest animal ever weighed, was a female specimen that tipped the scales at 190 tonnes (418,878 lb) and measuring 27.6 metres (90 feet 6 inches) in length. (The longer 33.57-m blue whale mentioned above sadly wasn't ever weighed but was likely significantly heavier than this one.)

At the other end of the scale, the record for the smallest sea mammal goes to a very special otter.

Incredibly rare, the South American marine otter (Lontra felina, translated as "otter-cat") is a small predator that likes to sunbathe along the rocky, kelp-rich shorelines of south-west South America.

Marine otters can be found in quiet littoral areas of northern Peru, Chile and in the extreme southern coasts of Argentina.

These predators are known to actively avoid humans, and they can measure between 87 and 115 centimetres (2 feet 10 inches–3 feet 9 inches) and weigh no more than 5 kilograms (11 pounds).

A hairy crustacean?

Everybody has seen crabs and crustaceans at least once in their lives, and we all have a mental image of how they should look.

But crustaceans can vary immensely in scale, shape and colour, and a lot of species have adapted to live in specific environments with very special requirements: some of these animals are impressively heavy, and some others are even covered in fur-like filaments.

For example, the Stygotantulus stocki, a tantulocarid, is a teeny tiny inhabitant of the oceans. Almost invisible, it has been recognized as the smallest species of crustacean (and also arthropod of any kind).

Diver in ocean

This amazing genus of crustacean measures only 0.094 mm long; that's less than a sewing needle tip.

On the contrary, the dramatic size of the American lobster (or North Atlantic lobster, Homarus americanus) made it the heaviest marine crustacean ever recorded. Thanks to its asymmetric claws and bright orange-red colour, this specimen is widely recognizable at a first glance.

On 11 February 1977, a giant lobster weighing a whopping 20.14 kg (44 lb 6 oz) and measuring 1.06 m (3 ft 6 in) from the end of the tail fan to the tip of the largest claw was caught off Nova Scotia, Canada.

Sadly, it was later sold to a New York restaurant owner.

Size isn't everything though: the yeti lobster (Kiwa hirsuta) has been described as the "furriest" crustacean.

This unique creature greatly differs from the image we normally have of crustaceans, and it lives in a very specific environment in the deep sea: hot hydrothermal vents on the seafloor in the South Pacific Ocean.

With a unique shape and a spooky white colour, the yeti lobster sports long claws and limbs covered in silky, blond-coloured filaments called setae that appear like fur.

Measuring an average of 15 cm (5.9 in) and considered blind, this little crustacean was discovered in 2005.

The name Kiwa takes inspiration from the goddess of shellfish in Polynesian mythology.