Can Starfish survive out of water? How long can they survive?

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Can Starfish survive out of water?

No, starfish can’t survive out of the water. They will soon die if exposed to open air.

These are water breathing and can use only their dermal gills present on the upper surface of the body to breathe.

Their breathing mechanisms has a lot to explain about why they can’t survive for a much longer time when out of water.

Starfish can only breathe underwater. Their gills are not true gills but partial ones.

They use their Papulae (singular: papula), also known as dermal branchiae or skin gills, that are projections of the coelom that serve in respiration and waste removal.

Papulae are really very soft skin gills of the starfish. These soft structures remain covered externally by the epidermis and lined internally with the peritoneum. They remain protected by pedicellariae while extending through the mesodermal ossicles.

The thin tissue of papulae allows gasses to move through it very easily, whether it is dissolved oxygen or carbon dioxide by a process called diffusion across the surface gradient.

This allows the exchange of gases in the dissolved form when underwater. That is by taking in dissolved Oxygen and giving out dissolved Carbon dioxide.

Now, when out of water these papulae, can take in oxygen from the air, and also can’t give out the exhaling carbon dioxide out of the body of the starfish.

As of now, when they are out in the open air they cannot exchange gases and as a result, they suffer from intoxication, usually with carbon dioxide or carbon monoxide. This causes them to die.

How long can Starfish last out of water?

A majority of the Starfish species won’t last more than 3 to 5 minutes out of the water and if exposed to the open air for so long they will surely die.

However, there are many that can only hold their breath for not more than 30 seconds and then they die. A vast majority of these species lies in the coral reefs and a lot of them in the deep ocean beds.

Talking about the largest starfish ‘Crown of thorns’ starfish (Acanthaster planci), they are only known to survive for not more than 4 minutes if exposed to the open air out of the sea coral bed.

A marine fish has a much longer lifespan if it is out of the water (just maybe 5 to 10 minutes), however, starfish don’t as their gills are not true kind of gills and only adaptable under the water.

There are other species as well that can last for hours that is between 2 to 28 hours out of the water. It’s because they can hold on to their breathe for a much longer time tolerating the stress.

Just for example, Sunflower Star (Pycnopodia helianthoides) is a kind of sub-tidal starfish from the Pacific sea that can last for about 1 to 2 hours on an average. However, some individuals can die as they can’t tolerate much of the stress.

Another example is the Ochre Star (Pisaster ochraceus), an intertidal star from the NE Pacific. They are known to survive out of water for about 28 hours but not all of the individuals will survive. It depends on their breath-holding stress tolerating level.


Should you take starfish out of the water?

No, it is not at all suggested that you take a starfish out of the water. It’s because taking starfish out of the water could be life-threatening to them.

The first reason for not to do such an act is because, if you bring them to the open-air they will die within 3 to 5 minutes due to carbon dioxide intoxication.

Even without taking them out of the water a lot, the constant handling, taking them out and putting them in the water many times, stacking them, putting them together, or placing them on top of each other as if they were a toy for our creativity, are conditions outside the way of life of these animals, which can also cause them to death.

They may also die out of mental stress that is the stress that can occur due to rough and wear and tear type handling of the starfish. This can also occur due to the change in the environment as the starfish is now out of the water.

It is also to be noted that they are very soft creatures and are born with intricate and fragile arms and tiny body structures.

And yes, starfish have a great regeneration capability to regenerate their lost arms. And also, do you know that, in spite of its regeneration capabilities, even the slightest touch or poke may hurt or damage them.

And so, when most people carelessly throw them out of the water, it’s very much obvious that it may damage or hurt them, thus leading them to death.


Can starfish come back to life?

If a starfish is dead then, it can’t come back to life. However, if that starfish have lost some of its body parts (as one of its arms) to predators then it can regenerate its lost part and can come back to life.

Incredibly, if the starfish is not dead, it can heal itself and even regenerate its parts resulting in a genetically identical starfish.

Regeneration is one of the most incredible biological features that they do have. This helps them to come back to life that is in that position as it was.

Regenerating their own arms is perhaps one of the most useful things a starfish can do. This genetic characteristic can be used in many different ways.

They can lose their arms when the starfish come in contact with a predator, or one of its arms maybe amputated (cut-off) in order to hide or escape from its predators.

However, regeneration can take time. Regenerating of one arm can take about 6 to 9 months, and even years to fully regenerate.

So, the starfish has to be in a pretty serious and emergent situation to lose one.

Their regenerating power is much more rapid when they are in their larval stages of the life cycle.

It has been seen that when the tiny transparent larvae of a starfish are being cut in half, each half is then able to regenerate to become a whole larva within a matter of days.

Scientists have found 9 different types of cDNAs, each one representing expressed genes or pieces of genes, that were only present in regenerating larvae owing to its regenerating genetic characteristics.


How do you know if a starfish is dying?

In order to know if a starfish is either dead or alive then the first thing you can easily notice are its tube feet.

Its tube feet are small suction-type feet with tentacles holding them, and these help them to hold the substrate and move from place to place.

When they are dead, these tube feet won’t move and will have lost their power of the vacuum to get on hold of the substrate it is on. If you see these tiny tentacles-shaped tube feet moving then it’s surely alive.

You will often find a dead starfish floating along with ocean water waves, as it will have lost its power to hold on to the substrate when dead.

You will also find it lying like a non-living rock at the ocean bed or coral reef. The ventral surface of the body where the stomach is present will often lie upward, while the dorsal part of the body downwards when it is dead.

Moreover, if you see one lying on the sand in the shoreline and there comes a rotten and disgusting smell from the starfish, then it’s surely dead.

For a majority of the people, it is very difficult to tell if the starfish is dead or alive. It’s because starfish are not very mobile animals and so it can be difficult to tell whether a starfish is dead or alive.

If you pet a starfish in the aquarium and you have known that the starfish is dead, then it should be removed from the tank immediately to prevent contaminating the tank.


Are starfish dead when they wash ashore?

Yes, starfish die almost instantly when they get washed ashore. It’s because when it is exposed to the open air it can no more breathe and so die within minutes.

It all happens because of their breathing mechanism and processes that only allow them to breathe when they are underwater and not out of the water.

Comparing starfish to that of a normal fish, you will often find a fish remain just fine if exposed to fresh air for just a moment, and starfish does the same as well if exposed to fresh air for just a moment.

But, that isn’t true. And yes, they can remain alive only for a few minutes but with excessive stress to breathing, as they don’t have true gills and not enough air tolerating power like those of the true fishes.

They get washed up to the seashore because the stormy weather can sometimes be another reason for the large masses of starfish getting washed ashore.

It is seen that starfish may appear to be stranded when they get exposed to open air for a very long time.

And just like fishes, they also have the ability to return back into the water when they’ve been exposed to the open air for too long.

So is not at all recommended to touch them if you find them lying at the beach and moving.

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