What Do Green Sea Turtles Eat?

The green sea turtles is one of the biggest turtles species in the world. They commonly grow to an average size up to 5ft and can weight over 600 pounds. Such a big turtle surely has to have a big appetite too, right? So it’s no wonder you’re probably thinking to yourself, what do green sea turtles eat?

Luckily for you there’s no need to look any further because we have all the answers you need. We’ll detail all the foods in which a green sea turtle eats in order to survive in the open ocean, so we hope you enjoy our article on, “What do green sea turtles eat”.

Green Sea Turtle Background

Environmental Habitat

There are two types of green sea turtle species. At this point in time, we’re still not sure if they are subspecies or completely separate species to one another. What we do know is, the Atlantic green turtle is found in the coastal seas surrounding Europe and North America. Whilst the Eastern Pacific green turtle can be located around the coastal regions from Alaska to Chile and further afield to North Australia.

Green sea turtles are currently listed as an endangered species. Unfortunately this has stemmed not form predatory threats but by human encroachment. Green turtles are still being illegally killed for their meat and eggs, as well as being accidentally caught in commercial fishing nets and drowning as a consequence. 


As we’ve stated before, green sea turtles are one of the biggest species of sea turtle in our oceans, with only the leatherback turtle commonly exceeding its size. Green sea turtles are usually sized anywhere between 80cm – 120cm in length, with the biggest recordings all being around the 150cm region. Relatively speaking, compared to an average sized human male, a green sea turtle would come up to their shoulders.

It’s very usual that male green sea turtles are bigger than females, and they also have longer tails too. Their heads are seemly small in comparison to their body size, which makes them easily identifiable in the wild.

Although green by name, the green sea turtle isn’t always green in colour. They’re commonly composed of colours including Brown, Olive, Grey, Black and Green. The “green” actually comes from the turtles fat being green in colour. The only species of turtle believed to be like this.

A green sea turtle has a smooth shell that is shaped like a heart. This is another identifiable feature, however it has to be in comparison to its size as the Olive Ridley turtles species also has a heart shaped shell, but only grows to be 60cm in length. 


Whilst most sea turtles species swim close to the waters surface to warm their bodies, green sea turtles will actually come on land to bask in the sun. Many people believe that turtles only leave the water to nest and lay their eggs. Whilst this is true for the majority of sea turtles species, it’s not the case for green turtles. They’ll sometimes come up onto coast line beaches to bask in the sun alongside other basking sea animals such as seals.

Green sea turtles, just like many other species, undertake a mammoth migrations from their favourite feeding grounds to the best nesting beaches. Sometimes these two locations can be tens of thousands of kilometres apart, which is a reason they only mate every 2 – 4 years.

Green Sea Turtle Diet 

What do green sea turtles eat? Did you know that throughout some point in a green sea turtles early years they will switch from being Carnivores to Herbivores. Thats right, juvenile green sea turtles are born to be invertebrates. This means they will feed on foods such as Worms, Jellyfish and Sponges for the first few years of their lives. Once they have matured into adult green sea turtles, they then switch their diet to become herbivores. Which means they will commonly only eat Sea grass, Seaweed and Algae. 

It is for this reason that the “Green” sea turtle gets its name. Before a green sea turtle is fully mature it will change its diet from carnivore to herbivore. This change in diet actually changes their bodies attributes. Becoming herbivores means that mostly their foods are green. This new green diet changes the colour of turtles fat, meaning their skin changes to a greenish colour as a consequence.

Juvenile Carnivore Diet

Marine Worms

Young green sea turtles will eat a variety of marine worms if they get the opportunity too. Marine worms are high in proteins which are crucial to its early growth. Feather Duster marine worms are amongst the favourites along the Atlantic coastal areas of North America. Once the young turtles mature and convert into herbivores, their growth rate seriously declines as a result of the lack in nutrients. 


From sea slugs and snails, to mussels and clams. These molluscs species are only a handful of typical foods for a young green sea turtle. With over 400 species of molluscs, it’s not hard to believe they these make the list of foods for young green sea turtles.

Plentiful and nutritious, these foods are a key part of a juveniles diets. Being located in all the green sea turtles oceans, these foods are available all year round, no matter where the turtle may be. 

Fish Eggs

Fish lay their eggs in hard to reach areas, mainly in reefs. Due to a juvenile green sea turtles size, they are able to access these hard to reach areas in which fish lay their eggs. Once they grow to a certain size, they simply cannot reach these areas any more. 

Fish eggs are harder to find than other foods, so these will be more of a treat for a young green sea turtle. Sometimes the easy access of other foods will usually take priority. Only when food is scarce will young green sea turtles find to find fish eggs. 


Small crustaceans are sometimes on the menu for juvenile green sea turtles. For example, time crabs and krill are amongst a few of a juvenile green sea turtles favourite. They are commonly much harder to eat than other foods available, but hold the most protein value. 

Crustaceans can be hard to swallow if not broken down properly priory to digestion and can cause internal cuts and abrasions as a result. These foods will only be consumed for the first couple of years, and will soon be discarded as meals.


Jellyfish can be found in all ocean waters, so for this reason they are a great starter food for young green sae turtles. Although they won’t be able to tackle big jellies, young green sea turtles will feed on small jellyfish to begin with. Jellyfish are easily accessible as they are fairly slow and in a large abundance. 

Jellyfish will also rise to the water surface to the young green sea turtle won’t have to dive down too far to find a meal, the jellies will come to them.


Sea sponges are another food which can be found in every ocean of our planet. These foods are easy picking for a young green sea turtle as they are commonly located near reefs which are full of aquatic life. They’re full of protein and nutrients which help young turtles to grow in the early stages of life.

Sponges are again very slow. Yes they do move along the sea bed, rocks and coral, however as a very slow pace. Therefore sponges are an ideal food for young green sea turtles when foraging. 

Adults Omnivore/Herbivores Diet

Although adult green sea turtles diet mainly consists of Grass, Seaweed and Algae, some do occasionally still feed on jellyfish and sponges. They will usually stay away from these foods, but in desperate times they will still feed on some Jellies and Sponges.


Seagrass is found in the shallows of salty water. It is commonly found around the coastal areas, rather than at depths. This makes it a perfect food for adult green sea turtles as they usually swim in the shallows to keep warm. Seagrass is commonly miscalled and confused with seaweed. Although very similar, seagrass is actually closer to the grass we see on land, then it is seaweed. Seagrass has roots, stems, leaves and sometimes even flowers and seeds. 

There are 72 known species if seagrass, all of which can be eaten by green sea turtles. Seagrass is often over looked as a food, but actually has more of an abundance than any other sea specie. It can even be seen in large quantities from space.


Seaweeds are macro algae what are again found all over the planet, in every one of our seas and oceans. They are a huge part of the aquatic eco-system, providing food for hundreds of animal species, including the green sea turtle. 

There are three main types of seaweed, each of which have subspecies within them. These three types are;

  • Brown seaweed  
  • Green seaweed
  • Red seaweed
Brown Seaweed

Brown seaweed grows in sub-tidal areas. The deeper down the seaweed grows, the darker its colour will be. These types of seaweeds tend to grow much larger than the other two types, and commonly create underwater forests. The most well known brown seaweed is called Kelp. Which is probably the seaweed you hear about most. (Specially in wildlife documentaries).

Green Seaweed

Green seaweeds are found in shallow waters. They are commonly the seaweeds you may see around shorelines as they need the most natural sunlight of all three types. The most common green seaweed is, Sea lettuce. This seaweed will most likely be the usual type of seaweed a green sea turtle may feed on due to it location in shallow waters.

Red Seaweed

This type of seaweed is the most recognisable, simply because of its colour. It is found on the lower shore, in tidal pools and coral reefs. It is most commonly harvested around the west coast, but can be found in locations including the polar waters to the tropics. 


Algae are aquatic, plant like organisms which young green sea turtles commonly feed on. They are a simpler form or structure of seaweed, structured from single celled phytoplankton. Algae is eaten by many aquatic marine life species and is believed to be “the food of the sea”. 

Different from seagrass and seaweed, algae lacks roots, stems and leaves. This means it floats on the waters surface or just below, and moves wherever the current or trades take it. Algae is believed to have been in our oceans for over 1.6 billion years. It is what has oxygenated our seas for millennia, as oxygen is the by-product of photosynthesis. 


Well that’s everything you need to now about “what do green sea turtles eat”. We hope you’ve enjoyed the article. Amazingly green sea turtles change their dietary requirements as they mature into adults.

Green sea turtles are the only sea turtle to come herbivores. However if times get tough, and food is scarce, they will eat jellyfish and sponges still.

Seagrass, Seaweed and Algae are a green sea turtles main diet when they’ve reach adulthood. Their diets will stay like this for the remainder of their lifespan which should range between approximately 60-70 years.

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