(BBC Earth) Humans can be tall or short, narrow or wide, but we don’t tend to talk about how long our bodies are.
That might explain why extreme length often catches our eye.And in any discussion of long animals, there are obvious leaders: snakes, the longest animals on land.

In April 2016, construction workers building a motorway in Penang, Malaysia claimed to have discovered a reticulated python (Python reticulatus) that was 26ft 3in (8m) long.
However, that figure was reduced to 24ft 7in (7.5m) by officials. Worse still, the snake reportedly died after it was captured so we will never know what size it could have grown to.
According to Guinness World Records, the longest reticulated python in captivity is Medusa, who lives in Kansas City, US. She is 25ft (7.67m).
But there have been claims the animals can reach almost double this length. Indonesia’s Fragrant Flower was famously said to measure 47ft 6in (14.5m) – until tape measures embarrassingly confirmed it to be closer to 23ft (7m).
“In my experience, most claims of maximal length and mass in snakes are over-exaggerated,” says Dan Natusch of the University of Sydney, Australia, who has spent several years researching large pythons.
“Reticulated pythons are harvested in large numbers for their skins. Over the last two years we have examined approximately 8,000 retics collected for this trade, of which two were longer than 7m [23ft] – just over, from memory. Traders claim the snakes do not get much larger.”
“My gut feeling is that 8m [26ft 3in] is probably maximal size for the species. That being said, it is plausible that the odd specimen might grow larger. The record of a 10m [32ft 9in] specimen from Sulawesi early last century may well have been true, but we cannot verify the accuracy of historical measurements.”
Natusch lists several species that are said to exceed the reticulated python record for length. These include the Australian scrub python, African rock python and probably the best known: the green anaconda (Eunectes murinus).
Native to the rainforests of South America, the green anaconda has been a subject of fascination ever since early adventurers first told tales of this seemingly impossibly long reptile.
Its remote home and secretive habits make it an ideal candidate for fiction, since it is very difficult to find specimens for accurate factual records. In the right conditions, without human disruption and with plenty of prey, it could grow to a gargantuan size and we would be none the wiser.
“The green anaconda is probably the only species with reliable size records near 8m [26ft 3in],” says Natusch. “Records of maximal length in the other species are dated, and I personally think they’re doubtful.”
That is pretty long, but animals on land can only grow so large. Most of Earth’s surface is ocean, and it is there that the true giants are found.
As the biggest animal ever to have lived, the blue whale (Balaenoptera musculus) seemingly obliterates any other animal’s chances at the length title. Even a new-born blue whale is longer than a giant reticulated python.
The largest blue whales are found in the southern hemisphere. There, length estimates for the Antarctic sub-species regularly nudge the 98ft (30m) mark.
The longest on record was a female 110ft (33.58m) long, captured by whalers in the South Atlantic. However, sightings of the leviathans are rare following their exploitation by such hunters. Scientists are now tracking populations via their songs to understand how they are faring following the ban on whaling.
It turns out there are some marine challengers to the blue whale. Rather than nose to tail, the first must be measured bell to tentacle.
The lion’s mane jellyfish (Cyanea capillata), named for its red-gold colour and mass of hair-like tentacles, is one of the largest jellyfish in the world. It is found in waters around Australia but reaches its biggest proportions in the cold waters of the northern hemisphere.
There, its bell can grow to 6.5ft (2m) in diameter and its tentacles are rumoured to reach 196ft (60m).
But it is clearly difficult to whip out a yard stick underwater and measure the translucent stinging tentacles of a moving jellyfish, so its true maximum length is unclear. You might have seen a doctored image of a jellyfish towering over a diver that regularly resurfaces on social media, further fuelling the rumour mill.
The largest specimen on record washed up at Nahant, Massachusetts, US in the 1860s. Its tentacles were measured at 120ft (36.5m) long.
In a 2015 review of marine giants, Craig McClain of the National Evolutionary Synthesis Center in Durham, North Carolina, US, points out that the lion’s mane jellyfish’s tentacles are fragile. That means it is particularly difficult to measure and we may never know how long it can grow.
If the relative thinness of its tentacles causes people to overlook the lion’s mane jellyfish’s extreme length, the same can be said of the bootlace worm (Lineus longissimus).
Living in and around rock pools along the west coast of the UK, it is a species of ribbon worm. It is dark brown in appearance, usually around 5mm thick, and produces stinky mucus when handled.
That description might make it sound pretty unremarkable, unattractive even, but when one was found on the shore at St Andrews, Fife in 1864 it got plenty of attention. It measured a whopping 180ft (55m) long and became officially the longest animal in the world.
As with all historical records, we have no way of knowing if the truth was stretched. The flexible worm could literally have been extended to satisfy record hunters.
In the scientific community, bootlace worms are said to average 16 to 32ft (5 to 10m) long but can contract their muscles to shrink their bodies when threatened. So next time you see a looping tangle of worm at the seaside, remember it could be the longest animal in the world.