But why is that? Why do living things steadily deteriorate as they age? While there are strategies to slow (or speed) the onset of senescence, it wɪʟʟ nonetheless happen one way or another. Only a few animals, however, are immune to the aging process.
A microscopic jellyfish known as Turritopsis ᴅᴏᴏᴍ, or more often known as the immortal jellyfish, is at the top of our immortal animal list. If a jellyfish is ɪɴjᴜʀᴇᴅ or ᴜɴᴡᴇʟʟ, it returns to its polyp stage for three days, converting its cells into a younger state before grᴏᴡɪɴɢ into adulthood again.
The scientific community is divided on whether these red ocean dwellers are physiologically immortal species; sɪᴄᴋness, not old age, is the most common ᴄᴀᴜsᴇ of ᴅᴇᴀᴛʜ, and they grow and ʙʀᴇᴇᴅ until they ᴅɪᴇ—though not with the same spouse, as these lifelong monogamous ᴍᴀᴍᴍᴀʟs do. According to Smithsonian, one lobster caught off the coast of Newfoundland was believed to be 140 years old, although most ᴍᴀʟᴇs live into their early 30s, while feᴍᴀʟᴇs live an average of 54 years. A fun fact about lobsters is that the larger they are, the older they are.
These ᴄʀᴇᴇᴘʏ crawlers, also known as planarian worms, are well-known for their ability to regenerate, since a worm sliced across or lengthwise can split into two independent worms. According to a study from the University of Nottingham, this seemingly infinite regeneration also extends to aging and ᴅᴀᴍᴀɢᴇd tɪssᴜᴇ, allᴏᴡɪɴɢ the worms to ᴀᴠᴏɪᴅ ᴅᴇᴀᴛʜ indefinitely.
THE PLANET’S MOST INDESTRUCTIBLE SPECIES
Anything that tries to kɪʟʟ a tardigrade wɪʟʟ rapidly learn that they are ᴅᴇᴀʟing with near-immortal crᴇᴀᴛures. “By entering a state of ᴄʀʏptobiosis, when their metabolism comes to a halt,” Pastor ᴀʀɢᴜes, these species can survive for thousands of years or even indefinitely. Here’s everything you need to know about the world’s most inᴅᴇsᴛʀᴜᴄᴛible animal, other from the fact that it’s exceedingly tough to kɪʟʟ.