Extreme Longevity: The Hydra lives for centuries
More than 500 millions years ago, a group of creatures seemed to have developed the key to eternal life and extreme longevity. The hydra is an animal in this group, and is a member of the Phylum Cnidaria (1-2).
The Hydra is a small 1 cm (0.4 inches)-long creature. It resembles a long cylindrical balloon with strings poking out of its head. This balloon structure is a hollow tube made up of a 2 cells-thick layer. The tentacles on the head have thousands of cells on their tips. Each cell contains a nano-sized dart-like thread structure, the cnidocyte (Latin: cnīdē (nettle) + –cyte (cell)). This can harpoon into a prey and immobilize it with toxins (3-4). Once paralyzed, the prey is swallowed whole into the hollow tube.
How does this Hydra live year after year after year? It is estimated to never grow old and live for centuries (5, 6, 7). Not only that, it is capable of restoring lost parts of its body. Cut it in half and a new head will arise out of the bottom half and a new foot out of the top half (8-9). In the image above, you can see the central hydra budding 3 fully developed baby hydra and a small bump suggesting the formation of a fourth.
In this article - the first of the series - I will walk you through the first step of 3 that allows animals to live for more than 500 years. You see, there is longevity and there is the extreme longevity that the hydra, giant barrel sponges, quahog clams, and the immortal jellyfish have.
- How to have extreme longevity: 1. Adapt to water (this article)
- How to have extreme longevity: 2. Add more stem cells
- How to have extreme longevity: 3. Keep adult stem cells young
How to have extreme longevity: 1. Adapt to an aquatic environment
Would you like to live to be hundreds of years old? And live those years - for the most part - without aging?
First: You’d have to adapt to living in water. Most of the creatures that enjoy extreme longevity - like clams, bowhead whales, Greenland sharks, sea urchins easily live 200 or more years: They all live in water. The only land-based creatures that have lived more than 200 years are the Giant Tortoises. Now, granted, you may not want to live as a tortoise; it would take you 15 minutes to move from your couch to go to the kitchen to get a snack.
Suppose you miraculously adapted to a watery environment, what species would you emulate?
Extreme longevity: Greenland sharks
How about a Greenland shark? They live about 400 - 500 years. But the disadvantage for this species of shark is that it’s pretty cold as they live in the Arctic in ice cold water with temperatures under freezing. Water can reach below freezing temperatures because of its saltiness as well the pressures that exist in the deep ocean (7,000 feet deep). Another disadvantage of Greenland sharks is that they plod along relatively slowly at 2 miles/hour; it’ll take you forever to get anywhere in the ocean. And to cap that, Greenland Sharks don’t reach sexual maturity for 150 years (10). So much for having a fun time in the water.
Extreme longevity: Quahog clams
How about emulating a quahog clam? Large quahog clams can live a long time (11) . Ming (aka Hafrun) has been identified as the oldest clam. Ming was found off the coast of Iceland in 2006; the clam was estimated to have hatched in 1498 or 1499 // 507 years earlier. He was named Ming since he was living at the time of the Ming dynasty in China.
As in Greenland sharks, quahog clams that take longer to reach sexual maturity live longer (11). This pattern - longer time to reach maturity = longer life - holds true for many animals (12). But an additional advantage that long lived clams have is that their reproductive ability continues and even strengthens in older ages (13).
The reason that quahog clams are so fertile is that they don't exhibit aging (14, 15, 16, 17) As noted in a previous article, low oxygen environments, cold water living, and food scarcity encourage cells to be healthier and longer lived. In fact, quahog clams are champions at surviving adverse conditions: They can stay buried for weeks to avoid predators. Experiments have documented survival after anoxia for 50 days (18). Living as a quahog clam gives you the triple advantages of extreme longevity, prolonged fertility, and strong endurance.
Extreme longevity: Hydra
It you’re not excited about living in cold waters, then your next best bet is to consider living as a Hydra. As noted above, those are under-an-inch creatures live in freshwater at temperatures of 65-70 º F . What they lack in size, they make up in agility and longevity. They have these tentacles that can spread much further than the length of their body to grab something to eat (19). You don’t have to look for the remote control anymore. You can stay on your couch and reach the TV monitor and even the fridge in the next room. Heck, the Hydra can have 6 -12 tentacles. You can be cooking supper in the kitchen while lounging on your couch.
And you don’t have to worry about injury if you’re a Hydra. If someone chopped off your head, you would create a new one within 3-4 days. There’s definitely a lot of advantages to morphing oneself into an underwater creature.
That’s the first thing you have to do to live hundreds to thousands of years: adapt yourself to an aquatic environment.
Next article: How to have extreme longevity: 2. Add more stem cells
Having strong stem cells - a lot of them - equals agelessness (20, 21). Complex animals (for example, vertebrates) don't have the luxury of a huge amount of stem cells (20).
In the second article in this series, I will discuss how extreme longevity seems to relate to the volume of stem cells that an animal has. This series of articles sets the stage for describing the key elements that keep stem cells healthy and vibrant - the key to a longer and healthier life.
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