Deep-water creatures, and most especially some invertebrates, are widely renowned for their ability to keep themselves alive longer than any other living creature on the Earth. Some of these species, such as deep-water sponges, certain types of jellyfish and clams, or the famed long-finned eel, are among the deep sea creatures who are able to adapt to their environments so efficiently, that they can increase their longevity to a great extent. Commonly placed among the oldest living organisms ever discovered, they are known for their ability to adapt to harsh environments and survive even when resources are extremely scarce.
Scientists are only just beginning to study and reveal some of the secrets of the underwater world. One of these secrets may actually be the key to longevity, with so many deep-water invertebrates and fishes being capable of living extremely long lives, in spite of – and possibly even as a result of – their ability to thrive in harsh environments where the water pressure is increased and the temperature is much lower than at the surface of the ocean. While these might be viable reasons for why some individual deep-sea creatures, such as deep-water sponges, may be capable of living in excess of 200 years, the complete explanation for these creatures’ increased longevity is still a mystery to science.
At first glance, sea sponges are just a regular type of sea-dwelling creature that lives at most for a few years in temperate climates. However, tropical deep-water sponges are far more impressive. A few calcified demosponges are known to only grow about 0.2 mm per year. While reproduction starts very early, the life span of the sponges is estimated to reach up to 200 years, or even more, depending on the stability of their habitats over long period of time.
Invertebrates are some of the most resilient creatures on Earth, and the invertebrates that have adapted, over millions of years, to thrive in our planet’s seas and oceans are also quite capable of extremely long lifespans, comparable in some cases to that of long living trees. Deep-water sponges are a good example of this, but there are also creatures such as sea urchins that are able to live for up to 200 years, as well as the ocean quahog clam. The latter has been known to reach the staggering age of 400 years. Probably the most impressive example of a long living invertebrate, however, is the Turritopsis Nutricula jellyfish – a species of invertebrate that can actually cycle itself back to the stage of immature polyp once it reaches maturity. This basically means that the creature may be able to live indefinitely.
Compared to the creatures listed above, very few mammals, birds or reptiles might even come close to the same level of longevity. While animals like the macaw might reach the respectable age of 80, only large underwater creatures have the ability to compete with deep-water invertebrates. Some of these include the koi fish (with some members of the species known to survive for up to 100-200 years), the 200 year old Greenland shark and the Galapagos giant tortoise, with a life span of about 100-150 years.