How Long Does It Take for a sea Anemone to Split?

Anemones are unusual creatures that have some rare behaviors. They get their name from the anemone flower, giving them the moniker “flower of the sea.” They are amazing with vibrant color arrangements and beautiful tentacles, which give them their flower-like appearance.

One of their unique behaviors is splitting. When you see an anemone begin to expand and separate, you might be wondering how long this process will take and if it’s an indication of poor health. 

What Is the Length of Time It Takes for an Anemone to Split?

It can take up to 24 hours for a sea anemone to split.  So, it could take only a few hours or even more than a day.  Observation of anemones splitting in the wild can take anywhere from three to five days.  But this depends on various factors, like reproduction time, environmental stress, and age.

Seasonal Changes

This splitting can happen at any time of year, but it most often occurs in the wild between August and February.  It is during this time their body size is larger than in fall and winter.  Researchers found that there is a positive correlation between the seasons when they split versus when they reduce in size.

How To Tell If an Anemone is Splitting?

If your anemone’s body is getting bigger, it’s a sign of splitting.  Various species will have different ways of doing this, so study your particular one.  There is no way to tell it’s going to split beforehand, you’ll know the day it happens.

The process begins with the body expanding.  Then splitting begins when the mouth or foot stretches more than usual.  You’ll see this activity most often during the day and it will split through the night. 

The Process

Here’s how the splitting process works step by step (generally speaking):

  1. The sea anemone elongates after attaching its most basal part to a rock.
  2. It then stretches into an oval, hourglass, or figure-eight shape.
  3. As it stretches, the tissue separates at the narrowest area.
  4. This stretching continues from where it’s attached to the rock all the way up to its mouth or oral area.
  5. The sphincter muscle surrounding the oral area is the last part to separate.
  6. Once divided in two, each half folds in on itself where the edges fuse together in a sort of healing process.  It is during this time it can regenerate damaged or missing internal structures.  This clone is literally an exact replica with the same DNA.

Why Does an Anemone Split?

There are two reasons why anemones split.  The first is because it feels in danger due to not enough food or bad water conditions.  This is a survival mechanism because it’ll have a better chance of living if there are two rather than one. 

The other reason is that it’s reproducing, making a clone of itself for propagation.  This splitting, or longitudinal or binary fission, is an asexual activity where there is budding off into identical twins. 

Do Anemones Multiply?

Yes, anemones multiply.  They can do this by asexual means, or binary fission, as mentioned above.  They can also reproduce through sexual means by broadcast spawning; meaning they release sperm and eggs into the water. 

External Fertilization

Ergo, fertilization happens in the water where larvae swim around until they find a place to reside.  When they find a suitable resting spot, they then become young anemones.  This process takes a few weeks. 

Internal Fertilization

In some varieties of anemones, fertilization occurs internally rather than from larvae.  The larvae come from the mouth, down the column, and sink into small depressions at the base of the parent’s foot where they change into a young anemone. 

They remain close to their parent until around three months old.  They then glide away and strike out on their own.  Anemones produced by sexual means aren’t the same as when they split, their DNA is completely different than that of their parents.

How to Know If an Anemone Is Healthy?

Sea anemones are beautiful because of their rare combination colors and unusual hues.  So, if their color is off, it’s an indication of poor health.  They are easy to contract diseases and experience health problems, so treating them the moment you spot issues will be crucial to their survival.

Anything like color loss, shrunken tentacles, lack of activity, or loss of appetite will indicate signs of health problems.  For instance, if they turn white, this could mean they’re stressed because of something in their environment not being right, like temperature, or not having enough food.

Copper is Poisonous

If you’re feeding medicine to other fish in the tank, ensure the medicine is free of any amount of Copper.  Copper will make anemones sick because it’s poisonous to them, they can die from it.

Unsuccessful Splitting

In the event of splitting, if your anemone doesn’t divide successfully, this isn’t a sign of bad health.  Sometimes, you’ll see the fission process begin and, for reasons unknown, will stop and retain its original form.


If you notice a scar on your anemone’s body after it splits, know this is normal.  This scarring will go away within a month or so, for the most part.  There’s always going to be a noticeable mark on their body from where they duplicated themselves.

Are Anemones Hard to Keep?

Yes, anemones are very difficult to keep.  Out of the 1,100 anemone species, only a handful can survive the environment of a reef aquarium.  Anemones have specific needs and an owner must attend to them throughout the day, every day.  Only experienced aquarists should have them.

Caring for Anemones

To keep an anemone, it’s imperative to understand their living requirements.  A lack of anything will create problems that often result in death.  But, if you’re able to provide all they need and maintain close observation, their mystery and wonder is something to behold.  Splitting is one of those amazing behaviors that indicate their happiness or stress.


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