How much plankton do mantas eat?

Feb 26, 2018 | About Manta Rays

One of our Facebook Live Broadcasts is about the diet of a manta ray. In that live video, I aimed to answer one of the most frequently asked questions we receive: “How much plankton do manta rays eat?

So, How Much Plankton Does Your Average Manta Ray Eat?

19,200,000.

Nineteen million two hundred thousand, give or take a few thousand.

That is the number of plankton pieces a ten-foot manta ray must consume weekly to stay alive.

WOW! This is a big number!

And now you’ve got the answer, let’s back up and explore how we came to that number.

How did we come to this conclusion?

I am not an expert on plankton, but we know over 5,000 species exist. This article on the National Geographic website can tell you more about plankton species.

When you turn on a light in the ocean at night, plankton is drawn to that light – like moths to light above water.

As you can see in the picture below, once the lights are on, the illuminated area looks like a snowstorm – these are all small pieces of plankton.

Large amount of plankton is attracted the big lights in the ocean to feed the reef manta ray

Plankton is attracted to the lights in the ocean.

Now, I cannot imagine how we would track how much plankton a manta ray eats in the wild, even if we could count how much they consume when at one of the manta ray viewing sites at night.

So… this research had to be done in a controlled environment.

Only four places are known for keeping mantas in aquariums – you can read about where to see mantas in captivity in this article.

Huge tanks are needed to keep a manta alive, and swimming and huge amounts of plankton must be fed to each manta ray weekly.

So the aquariums in Georgia (USA), Lisbon (Portugal), Atlantis (Bahamas), and Okinawa (Japan) came up with this number and discovered that a manta ray needs 12% of its body weight in plankton per week to survive.

Anyway, this leads to the following math equation for a manta with a 10’ wingspan… if you’re into stats and numbers, you are going to love it 😁

Let’s do the math…

  • Every foot of a manta ray weights 100 lbs
  • This makes our example 10-foot manta ray a 1,000 lbs creature
  • 12% of 1,000 lbs equals 120 lbs of plankton

A few years ago, Kara Osada-D’Avella studied the plankton on the coastline and established that 10,000 pieces of plankton weigh 1 dry ounce.

There are 16 ounces in 1 lb, concluding that a manta ray consumes (120 x 16 x 10.000) 19,200,000 pieces of plankton weekly.

What an awesome number, and yes, Mother Nature created a beautiful ocean angel and a gorgeous creature with one big mouth!

To learn more about how manta rays feed on this amount of plankton, find additional in-depth information in the articles linked below.

Recommended reading

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