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Sea Creatures with Incredibly Long Lives

Suprita Biswas
The fact that an organism can live for hundreds of years, is quite astonishing in itself. Life for such creatures is an amalgamation of adaptability, evolution, and some unique physical features, that make them what they are; near immortals.
Turritopsis nutricula, or the immortal jellyfish, can only die due to diseases or predatory attacks, and NEVER due to old age. They are the only creatures known, to have this unbelievable ability.
The diversity of the marine biome is not unknown to anyone. From fish to octopuses, and microscopic picoplankton to whales, marine wildlife contains the highest number of life forms on the Earth.
Two-thirds of the Earth is covered with water (oceans, seas, freshwater rivers, lakes, ponds, etc.), and it is enthralling to know that some of these fascinating animals have lived under the layers of the water since hundreds of years.
Most of the creatures with incredibly long lives, are mostly found below the depths of oceans and seas, and very rarely will you find a creature of the land, to have a very long lifespan. The most common characteristic among these creatures is the growth rate.
You would be surprised to know that a slow growth rate helps these creatures to live for such a long period of time. Physical and sexual maturity eventually leads an organism to perish. Therefore, a slow growth rate, slows down the entire process of its life cycle, thus increasing its years on Earth.

Sea Creatures that Live Long

The Immortal Jellyfish

The immortal jellyfish, or Turritopsis nutricula, is the only known organism to have the ability to revert to the immature state, after achieving complete sexual maturity, and therefore, is rendered immortal.
This creature was first identified in the year 1983, on the floor of the Mediterranean Sea. While conducting a research on hydrozoans, a scientist named Sommer discovered this enthralling being, which showed the ability to age in reverse, i.e., grow younger and younger.
Upon maturity, on facing mortal crisis, starvation or predatory attack, it reverts to its initial state and starts its life cycle, all over again. This creature achieves this uniqueness of immortality by a cell development process called transdifferentiation; wherein it is able to alter the cells and transform into polyps of a polyp colony.
A Turritopsis, however, does die. It can only revert upon achieving sexual maturity, and therefore, is equally vulnerable to diseases or attacks in the polyp stage. This species is now being closely observed with the hopes of some breakthrough.
Sea Turtle
Any account about long-living creatures is incomplete without the mention of turtles/tortoises. These animals are famed to live very long; the record of which is held by one aldabra giant tortoise called Adwaita, who lived for more than two centuries.
There are currently seven living species of sea turtles; hawksbill sea turtle, loggerhead sea turtle, olive ridley sea turtle, Kemp's ridley sea turtle, flatback sea turtle, leatherback sea turtle, and green sea turtle.
Like all other sea creatures with a long lifespan, turtles too are blessed with a very slow growth rate, and can take decades to reach sexual maturity. Though the marine turtles breathe air, they have adapted to sustaining underwater for a very long period. Their size varies from 100 pounds to 1000 pounds, depending on the species.
Sadly, all the species of sea turtles are listed in the threatened/endangered animals records. These beautiful creatures face many threats, illegal shell trade, marine pollution, entanglement, coastal armoring, harvesting for consumption, and climate change, being just a few of them.
Bowhead Whale
The bowhead is a baleen whale (Balaena mysticetus), meaning, that instead of teeth, these whales have baleen plates for filtering food from the surroundings.
The name comes from the fact that they have a bow-arching mouth, and the size of the head is nearly 40% of the entire body. Adults are entirely black, with a white patch around the chin area.
This huge mammal can grow up to 55 - 60 feet in length, and can weigh between 70 - 100 tons. Surprisingly, a bowhead comes next to the blue whale in weight, however, several other whales are bigger in size. A bowhead whale is among the longest-living whales, and after analysis, scientists have concluded that they can live for more than 100 years. These whales reach sexual maturity around the age of 20.
A bowhead is capable of breaking through an ice layer of minimum 7 inches thickness. It can achieve this feat due to its huge head and extremely strong body. This huge and interesting creature has suffered serious exploitation, and the number has depleted considerably. However, the good news is that apart from a few populations, these whales do not fall under the endangered species.
Red Sea Urchin
Red sea urchins or Strongylocentrotus franciscanus are found in a range of colors, from red and orange, to burgundy, and sometimes even black.
Sea urchins crawl slowly over the surface of the floor using their spines. They are only found in the Pacific on shallow waters, between 90 meters to about 300 ft.
The body of a sea urchin is encased in a hard shell, known as 'test', which is again completely covered by spines. Their size ranges between 15 to 18 centimeters. The animal has a mouth, which is located at the bottom of its body. Sea urchins have the ability to regrow their spines. They are known to mostly live beyond 30 years, however, some specimens have been found which have lived beyond two centuries.
These animals can be called the porcupines of the sea. The spines on their body protect them from predators. The sea floor covered in sea urchins is a spectacle in itself, however, proximity to them can be dangerous, as their spines are poisonous and can cause infections. There are, however, a few harmless varieties like the purple and green sea urchins.


Geoduck (pronounced as 'gooeyduck'), belongs to a species of saltwater clams, and is the largest burrowing clam in the world.
The clam is not very huge in itself, however, the long siphon of a geoduck, which can be as long as 2 meters in length and is mostly known as the 'neck', makes the clam quite long.
Geoducks filter water using their siphon, derive the necessary nourishment in the form of plankton, and eject the water through another hole present in the siphon. These help them to remain in one place for long periods, without going through much activity. The long life of geoducks can also be attributed to the fact that they do not have many predators. Geoducks have a life expectancy of 100 years, and the longest known lifespan is of about 165 years.
Geoducks are known to have aphrodisiac properties, and are therefore, on a high demand, mostly in Asian countries. They are farmed and harvested, as the demand for them is ever increasing, along with the rise in prices.
Rougheye Rockfish
Considered among the longest-living marine fish, rougheye rockfish is known to live for as long as 200 years. On most occasions, this fish is confused with the Shortraker rockfish, due to the likeness in features.
Rougheye belongs to the family Scorpaenidae, and its name comes from the most distinct feature of the fish; the spines that are present along the lower rim of their eyes. It has a red or pink body, with gray patches. It is also sometimes referred to as the 'blacktip' rockfish, as the ends of its pectoral fins are marked black. Rougheyes live at a depth between 550 to 2000 feet. This fish has a very slow growth rate, and matures at an equally slow pace.
These creatures are vulnerable to overfishing, and many get caught before even reproducing. High fishing for rockfish has reduced their population, however, laws and regulations in many parts of the world have contained this process, and species of rockfish are slowly recovering.
Ocean Quahog
Mostly found in the North Atlantic Ocean, ocean quahog is a bivalve mollusk (a species of clam), found at a depth of about 8 - 400 meters, and not beyond a water temperature of 16 degrees on the Fahrenheit scale.
It is interesting to know that quahogs are one of the slowest-growing animals on the earth, and age is calculated by the number of rings on the shell, much like the tree rings. The shell is mostly thick, glossy, and brown in color.
They mostly bury themselves completely in the soft sand, with a tube extending up to the surface, for maintaining the supply of oxygen and food. Quahogs grow very slowly, which is one of the main reasons for their long life, and may take up to 50 long years to reach the proper size. They may then live up to 400 years.
Quahogs are at a risk from bottom fishing, and belong to a species of clams which are edible. Like any other slow-growing species, it is difficult to recover the population of quahogs, in case of excessive fishing/consumption. Quahogs have found their way into the OSPAR list of threatened/declining species.
Antarctic Sponge
As the name suggests, Antarctic sponges are found in the Antarctic Ocean, and are counted among the oldest living creatures that dwell the Earth. They are known to live for centuries, if they are left untouched by predators.
Interestingly, sponges were considered plants before Aristotle discovered their true identity. Sponges are immobile, and this feature is considered one of the prime reasons of their long life, the other being extreme low temperature of the ocean. These sponges come in different colors, shapes, and sizes; however, all varieties live on the sea floor.
These amazing sponges lack any protective outer shell, and therefore, are highly vulnerable. However, with age, these creatures have developed many defensive mechanisms (in most cases, chemicals), which protect them from sea stars, turtles, invertebrates, and creatures which primarily feed on sponges.
They are also believed to use their brightly-colored bodies to scare away predators.

Antarctic sponges follow the process of filter feeding, using the specialized feeding cells. Their bodies are extremely simple, when it comes to design. However, they are known to be complex, primitive animals, and definitely carry many secrets deep under.
These creatures are among those beautiful animals that have survived the numerous natural threats and calamities, and have adapted themselves to the changing surroundings. However, constant human interference is bound to threaten their existence, and therefore, it is of utmost importance to spread awareness. The lives of all living beings are equally important. If they die, we cannot survive either!