Seagrass species spotlight: green sea turtle

20 April 2022  /  By Esther Farrant, Education Officer

Esther Farrant

Esther Farrant

Seagrass meadows can be found on every continent of the planet, except Antarctica, therefore they are habitats for both temperate populations and tropical residents.  One such resident is the majestic green sea turtle.

Here at the National Marine Aquarium in Plymouth, we have a resident green sea turtle of our very own. He is a rather cheeky chappy called Friday who can be visited in our Atlantic Ocean Exhibit, the deepest tank in the United Kingdom!

Green sea turtles start their lives feeding omnivorously on crustaceans, jellyfish, squid, algae, and seagrasses.  As they age and become teenagers, green sea turtles no longer need an omnivorous diet profile, and become herbivores.  Adult green turtles will consume around two kilograms of seagrass every day in the wild, highlighting why it is such an important habitat.  Here in the Aquarium, we attempt to replicate this herbivorous diet when feeding Friday; we provide a gourmet selection of vegetarian delights, including broccoli, lettuce, cucumber, bell peppers, and cauliflower. However, despite a delicious selection of natural diet options, Friday still reverts to childhood behaviours and attempts to steal squid and fish from the shark feeds!

Turtley amazing

Green Turtles are not named based on their external shell colour which is usually a dappled brown shade. They are called green turtles because their fat under their skin is green from the large quantities of plant matter that they consume.  Weighing up to 320kg, green turtles are among the largest turtles in the world.  Our turtle, Friday, is the heaviest of our marine residents, weighing in at 130kg. But he still has a lot of growing to do!

Ocean Image Bank/Amanda Cotton

Green Turtles are travellers. Like other sea turtles, they undertake lengthy migrations from feeding sites to nesting grounds, normally on sandy beaches. They are listed as an endangered species. Despite this, they are still killed for their shell, their meat, and sadly their eggs. Their numbers are also reduced by boat propeller accidents, getting tangled in ghost fishing nets which causes drowning, and the destruction of their nesting grounds by human encroachment.  Most relevant to us here at ReMEDIES is the sad degradation of the green turtles’ seagrass habitat and food source.  The expansion of essential habitat restoration projects such as ours are evermore important for spectacular marine creatures like the turtle.

Top Facts:

  • Green Turtles are older than the dinosaurs! Sea turtles are reptiles whose ancestors took to the sea about 150 million years ago. They are one of the few species so ancient that they watched the dinosaurs evolve and become extinct.
  • Bum snoring – Turtles breathe with their lungs so have to surface every 10 to 30 minutes to breathe from the air. However, when sleeping their activity level is reduced and the turtle can remain underwater by breathing through its butt for around 4-7 hours! A process called cloacal respiration.
  • Faster than they look; on land turtles are slow, but in the water, their powerful flippers allow them to swim gracefully at speeds up to 35 mph!
  • Sex of turtles is based on environmental factors; Less dense, warmer sand decreases incubation time and results in more female hatchlings, whereas colder temperatures generate male turtles.