Did you know white beach sand is fish poop?

Nov 08, 2011 · Curiosities

White Sand Beach

Yes, and I’m not joking!!   But if at the moment you find yourself on one of these beaches, and barefoot, you don’t have to rush for your sandals!  Now that you know that the sand you are walking on is made up of minute excrements of this fish, here’s the explanation why you shouldn’t feel sick or be put off.


So, why doesn’t it smell?

Well, the truth is that the excrement is really small pieces of coral which the parrot fish spend their time nibbling during the day.  It doesn’t feed off the coral, it eats seaweed and polyps from the surface but, at the same time and because of its beaked mouth, it gets a ‘plus’ of hard coral which it breaks up with the teeth in its throat.

The parrot fish can’t metabolise this coral so it ‘throws it overboard’ in the form of grains.  The existence of this species of fish is essential to the survival of the coral as it acts as a ‘natural cleaner’ of parasites, etc. that grow on it, so without the help of the parrot fish the coral would die. If you find yourself near one of these fish you will find them munching and making crunching sounds with every bite.

Parrot Fish Beak Mouth

Another reason is that they need to do this constantly in order to keep their beaks clean and that they (the beaks) don’t grow too much.  We’re talking about an insatiable fish that spends the whole day eating and ‘discharging’ without a break and that’s why just one parrot fish can produce 100 kg of white sand every year!!  Thinking about this then, to those of us who adore paradisiacal beaches, it’s obviously important that there is an abundance of the parrot fish.

Just imagine, 100 kg of white sand a year for every year of the life of the fish… taking into account that it is one of the most abundant in the coral reefs.. and after thousands upon thousands of years of existence….. imagine the amount of white sand these colorful fish have produced.

Beach Sand Magnified Zoom

Of course, this doesn’t mean that all the white sand to be found on tropical beaches comes from the back end of this fish: scientists confirm that these fish are responsible for about 70 per cent of all the sand on the tropical beaches. I have magnified the photo of the sand about 30 times and you can see it on the right: together with other sediments dragged along by the rivers into the sea, among the grains of sand you can see tiny fragments of shells that get crushed by aggressive waves from the sea, especially during storms.  All of this ‘paints’ our beaches a little so that they aren’t as white as talcum powder…..

With 100 kg of white sand a year it’s a pity that the currents aren’t strong enough to carry some of these grains of sand to the coasts of the colder countries in the world, don’t you think that this would brighten up their beaches! Although sometimes the sand can be even whiter than snow like that of the Hyams beach in Australia, that holds the Record Guinness for having the whitest sand in the world. We have visited Hyams to analyze its unusual sand and make a video which you can find on this other article. 

However, thank god we have parrot fishes in our desert islands!

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{ 35 comments… read them below or add one }

Juan V Cruz May 24, 2012 at 6:17 am

So I will not go to the beach anymore!

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Frank Southwell April 12, 2013 at 2:35 pm

Juan.. you can't be that naïve. If you knew what was in your sandwich, you would not eat that hotdog either.. LOL

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Alvaro Docastaway April 14, 2013 at 4:41 pm

haha However, I guess Juan was being ironic :)

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Alicia Gimenez Hidalgo May 24, 2012 at 6:56 am

very interesting Alvaro!

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D. Erik Emison September 9, 2012 at 9:42 am

What an amazing fact supported with other colorful taken for granted scientific aspects in where nature’s and humankind’s ideal of beauty correlates. Excellent writing!

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Alvaro Cerezo November 26, 2012 at 8:32 pm

Thanks a lot!

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Ryan Supan Leis September 18, 2012 at 4:01 am

So dark beaches are biologically dead? no coral reefs!

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Alvaro Docastaway October 11, 2012 at 7:40 pm

Dark beach sand is a mixture of sand from rivers and other sediments. That's one of the reasons why beach sand on mainland has darker colour

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James Curtis February 20, 2013 at 4:50 am

The term black sand beach has been used only for beaches dominated by grains of black volcanic glass

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Alvaro Docastaway March 3, 2013 at 2:23 am

Right!

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Frank Southwell April 12, 2013 at 2:34 pm

Ryan.. you did say something correct.. "no coral reefs". On the volcanic islands of the Caribbean, namely Montserrat and Dominica, the beaches have fine grained, black, volcanic sand, which provides the abrasive ingredient for pumice hand cleaner and sandblasting. As Alvaro Docastaway mentioned, sand is created by different means which accounts to the great variation in size, colour, density and texture. The island of Barbuda has one of only two PINK sand beaches in the world. That pink sand is the crushed shells of the conch.

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Alvaro Cerezo April 14, 2013 at 5:45 pm

Thanks Frank for your interesting explanation

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Alvaro Docastaway May 8, 2013 at 2:40 am

Thanks for your input Franck!

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Alvaro Docastaway May 8, 2013 at 2:42 am

Thanks Franck, appreciate your input

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Fernando Santos Jr November 8, 2012 at 6:38 pm

Nice to know lol.

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Alvaro Cerezo January 26, 2014 at 6:02 pm
James Curtis February 20, 2013 at 4:52 am

This is why I don't go to the beach…It's a litter box.

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Alvaro Docastaway March 3, 2013 at 2:21 am

hahaha

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Ariel Padigos March 6, 2013 at 6:15 am

haha

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Maya April 2, 2013 at 4:46 pm

Wtf

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Maya April 2, 2013 at 4:48 pm

Wtf
No it’s not its white coral

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Alvaro Cerezo April 14, 2013 at 5:51 pm

It’s fish poop!! :D

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Noemi meza April 2, 2013 at 4:48 pm

Thanks ALOT !!!!!!!

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Alvaro Cerezo April 14, 2013 at 5:53 pm

You are welcome!

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Frank Southwell April 7, 2013 at 2:52 pm

That's why the Parrot fish should be protected.. It keeps the coral alive and clean and produces sand at the same time..

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Alvaro Docastaway April 14, 2013 at 4:38 pm

exactly!

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kim sweeney June 30, 2013 at 9:20 am

Can any of this sand get into our pores and continue to grow as reef?
our pores are warm and wet with saline solution. I go to Hapuna Beach exclusively, and have always wondered about this.
Aloha

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Alvaro Cerezo July 29, 2013 at 5:00 am

That’s a difficult question. Better for a doctor. However, I guess it is impossible for 2 reasons:

1 – Coral needs a hard surface to start growing. Check this video http://vimeo.com/5712168

2 – I guess humans have got some protection in our skin that stops the process

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UNKOWN October 10, 2013 at 4:51 pm

Boobies are nice for men

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Idrees January 23, 2014 at 8:50 am

this is wrong! its not fish poop. coral beach sand is a result of years of coral erosion. corals are made by a small creature called polyps. polyps extract calcium from sea water and create coral structures in the form of reefs. these reefs are then eroded by natural forces and we get coral sand and the sand forms islands with white sandy beaches.

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Alvaro Cerezo January 26, 2014 at 6:11 pm

Hi Idrees

Thanks for your remark. All you said is true, but parrot fish is a big responsable of sand creation.

It is easy to understand by comparing how much sand one parrot fish can defecate in a day, and how much sand it is created by erosion also in a day.

If you have time, please have a look at wikipedia
http://en.wikipedia.org/wiki/Parrotfish#Feeding

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Bob Palik February 14, 2014 at 3:36 am

I have seen black sand beaches on the island of Moorea in French Polynesia. Moorea is surrounded by a coral reef. So both black and white sand beaches do occur on the same islands. That is due to concentrations of volcanic glass in some places and parrot fish excrement in others.

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Alvaro Cerezo February 16, 2014 at 5:04 pm

Thanks Bob for your interesting input! :)

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Hugh Jasol September 1, 2014 at 6:09 pm

Daddy! Daddy! Where do the dirty needles and used beer cans come from?

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Alvaro Cerezo September 1, 2014 at 6:30 pm

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