Ageing Differences Amongst Organisms

Abhidyu Ajila
7 min readOct 29, 2022

Throughout evolution, we’ve studied many organisms that have existed on Earth, some huge as Sauropods from the Cretaceous to modern-day organisms as small as a ferret. Various studies are conducted to understand their way of functioning and get a clear picture of how these organisms have adapted to this rapidly evolving world. Whether it be by completely changing their diet to adapting to a slow lifestyle, there are a plethora of evolutionary and behavioural changes occurring due to changes in the ecosystem around these organisms such as lack of food, changes in physical or chemical parameters such as temperature and pH of the water and so on. But one of their most unique things is how these organisms age. In this article, I’ll talk about some organisms and how some of them have different lifespans.

Picture Credit: The Guardian

Organisms Of The Past

To start with, let’s discuss some megafauna of the past and how some of them managed to survive for longer lifespans than others. For starters, longer lifespans are associated with larger organisms so the sauropods of the Cretaceous and Jurassic periods would take the crown on this one such as Diplodocus and Brachiosaurus.

Picture Credit: Pinterest

These massive sauropods were plant eaters and had an estimated lifespan of around 80 to 100 years, making them one of the longest-living organisms on our planet. But how did they have such longevity compared to theropods of that time such as Tyrannosaurus Rex and Carnotaurus Astrei?

Picture Credit: Jurassic Wiki

See even the big one in the picture above is trying to scratch its head but hear me out. Predatory dinosaurs like the Tyrannosaurus Rex lived for only 28 years, while they were ferocious predators known as the tyrant lizard for a reason, they also had high assimilation and metabolic rates compared to Brachiosaurus which meant they had to eat whenever they were hungry. While dinosaurs like Brachiosaurus were massive organisms that required around 400 kgs of food every day, the Tyrannosaurus Rex required around 140 kgs of meat every day.

Picture Credit: Quora

This allowed them to grow around 26 metres tall long and weigh 28 tonnes or more- that’s equivalent to 4 African elephants compared to the Tyrannosaurus Rex which weighed around 8 tonnes and measured 12 metres. This constant eating allowed them to grow in massive sizes and helped them avoid predators like Tyrannosaurus Rex in turn allowing them to live for longer periods than the carnivores of that time.

Another factor was the availability of food, while the carnivorous dinosaurs had to hunt down prey with minimal chances of success, the herbivores had an abundance of food at their disposal. These factors allowed brachiosaurus and other sauropods to have a longer lifespan compared to predators

Modern-Day Organisms

You might be wondering if there are any organisms in our present world to have a long lifespan like the Sauropods mentioned above, the answer is yes! Certainly, we have many creatures that are surviving alongside us on our planet in the 21st century that have greater lifespans and I’ll be talking you through some of them.

Bowhead Whale (Balaena mysticetus)

Bowhead Whale Picture Credit: David Briggs

Bowhead whales are baleen whales that are extensively found in the Arctic. These whales are one of the most intriguing organisms that measure around 60 feet in length and weigh in at 90,000 kgs, they are one of the only large whales that have adapted to live in icy waters thanks to their blubber that’s 1.6 feet thick. Bowheads also possess one of the strongest skulls by which they can easily crush sea ice 7 inches thick in front of them. Adults of these species are completely black except for a portion that’s under their faces. What’s more interesting is that Bowhead whales are the longest-living mammal to exist on our planet, the recent studies of sharp harpoon tissue and their eye tissue gave researchers an indication that they can survive for more than 200 years, but what’s their secret to this longevity?

Picture Credit: World Wildlife Fund

One of the reasons is the ability to reduce their metabolic rate per the surrounding temperature. Along with that, despite having 1000 times more cells than humans which should make them more susceptible to diseases like cancer, Bowhead whales have well-developed anti ageing and anti-cancerous cells that provide cancer resistance and also better DNA repair boosting their ability to live longer.

Galapagos Giant Tortoises ( Chelonoidis niger)

Galapagos Tortoise Picture Credit:

One of the most intriguing organisms on our planet just as ancient as time itself, These inhabitants of the Galapagos Archipelago are one of the large tortoises on Earth. This tortoise species is one of the longest-living members of the family Testunidae and can live up to 200 years respectively. These tortoises reach lengths exceeding 5 feet and can weigh around 400kgs. Their shell sizes and carapace shape varies amongst the 15 subspecies that are found across the island chain. They are one of the dominant megafaunas of these islands which are also home to some unique organisms and the birthplace of many theories postulated by well-known naturalist Sir Charles Darwin during his voyage to the Galapagos Islands on the Beagle during the 1800s. These tortoises have an unusual carapace shaped like a saddleback which allows more vertical reach that helps them browse higher vegetation such as Opuntia that grow in arid areas. Galapagos tortoises are herbivores that feed on milkweed, lichens, opuntia, berries and grass.

Picture Credit: The New York Times

The primary reason behind their longevity is thanks to their slow metabolism along with their high number of anti-cancerous cells and better DNA repair mechanism that's pretty similar to Bowhead whales that allow them to, you guessed it live longer!

Greenland Shark (Somniosus microcephalus)

This one is an animal that I'm pretty fascinated with, this one is called the Greenland Shark and it is one of the most interesting fish found in the waters of the Arctic towards the warmer waters of the Northern Pacific Ocean they measure around 23 feet long and weigh around 1000 kgs and are pretty much found in depths of around 2200 metres (7200 feet). Their diet majorly consists of fish, seals, and squids and are known to eat carrion (leftover meat from other prey killed by another predator). They are also known to hunt Polar Bears.

Picture Credit: Awesome Ocean

These sharks are related to sleeper sharks and tend to move at a slower pace at around 3kms in an hour. Along with that, these sharks are well-known to be docile and not aggressive, but don't let that fool you they are fearsome predators that even the fishermen hate in the Arctic waters due to their habit of getting tangled in fishing nets while scouring for prey, which in return destroys the fishing equipment on their ships. But there is something unique about them in that they are the longest-living fish in the world with a lifespan between the 250-500-year mark.

Picture Credit: Live Science

The most intriguing fact about this is that their hearts beat super slow about a heartbeat every 12–25 minutes compared to humans at around 60–100 every minute. They also possess a strong immune system and a pretty slow metabolism that allows this creature to have such longevity.

Surprisingly, humans have an ability that even these organisms mentioned above don't have, do you'll know how? I'll leave you guys the readers to answer this question. If you'll know how then feel free to share the answer in the comments section. As always if you like what I write then please like and consider sharing it with your friends and fellow nature enthusiasts.

As always have a great day and take it easy 😁

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Abhidyu Ajila

A zoology student who talks animals, conservation, evolution and geography