Sea Turtles of Costa Rica

Right, let's start with the facts.

All tortoises are turtles, but not all turtles are tortoises.

But what does this even mean?

Oftentimes, many people use the two words interchangeably. However, this is incorrect. 

Unlike tortoises, which spend the majority of their lives on land, turtles are found in freshwater or marine environments. Sea turtles spend nearly all their lives in the ocean, only coming to shore to lay their eggs. In Costa Rica, there are 5 species of sea turtles.

In this article, we'll be exploring exactly what a turtle is and the different species of sea turtles that can be found in Costa Rica. 
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I have been fortunate enough to work with 4 of the 7 species of sea turtle found across our globe, aiding with vital scientific data collection. In other words, I know a thing or two about sea turtles.

What Is A Turtle?

A lone olive-ridley sea turtle coming ashore to lay eggs

A turtle is a type of reptile that has its body encapsulated within a bony shell.

Yes, many animals have shells. However, the architectural ingenuity of the turtle shell is what sets it apart.

The shell of a turtle consists of two sections: the top (carapace) and the bottom (plastron). The two sections are made of bone and cartilage.

A turtle cannot survive without its shell.

Not only is it a vital component in the protection against predation, the shell of a turtle contains important anatomical structures, such as their rib cage, spinal cord, blood vessels and nerve endings.

The shell also acts as an essential reservoir of fat, water, minerals and waste products.

The top carapace and bottom plastron are fused together at the side of the body, creating what's known as a skeletal box. This, in part, ensures that the shell of the turtle remains in place and cannot be shed.

Unlike tortoises, which are found solely on land, turtles live both on the land and in aquatic environments - both marine and freshwater.

The anatomical differences between turtles and tortoises will allow you to distinguish between the two groups. 
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Whilst tortoises have stubby legs with distinct claws, turtles have flat, oar-like flippers. These anatomical differences correspond to the particular habitat the animal can be found in - be it the open ocean or on the desert floor.

Sea Turtles In Costa Rica

I have had the privilege of working with a range of sea turtle species across the globe.

Sea turtles have a large geographical range and, as such, can be found in a large variety of countries.

I have worked with green and loggerhead turtles in Cyprus. However, I have also worked with green turtles in Costa Rica.

In Costa Rica, I have also worked with olive ridley and leatherback turtles. Here. I worked with marine biologists to collect geometric data and satellite tag individuals. 

Below are the 5 species of marine turtles that can be found in Costa Rica:

1. Olive Ridley Turtle

A marine biologist monitors a nesting olive-ridley sea turtles. Her eggs will be translocated

Olive ridley turtles are the most numerous sea turtle species on the planet.

In fact, they are so populous, that at certain times in the year, hundreds of thousands can be seen nesting in just one place.

These large aggregations of olive ridley sea turtles are known as arribadas, or, in English, mass arrivals.

There are 6 known arribada sites in the world, two of which are found in Costa Rica: Playa Ostional and Playa Nancite - both beaches of which are found in the province of Guanacaste, Northeast Costa Rica.

Although arribadas can occur throughout the year, the largest aggregations occur in the rainy season, between the months of September - November.  The event is thought to be triggered when the moon enters its final quarter.

Each female can lay anywhere between 70 - 110 eggs. During an arribada, millions of eggs can be laid.

Of course, not all these eggs survive. Many are crushed and destroyed by the continuous onslaught of determined nesting females. Others are predated on by a range of animals, including crabs, birds and mammals.

Olive ridley's get their name from their distinct olive hue to their carapace - a colour that develops with age.

As far as sea turtles go, olive ridleys are relatively small. Their distinctive hump-shaped shell measures no more than 70 cm - I spent many sleepless nights collecting shell measurements of olive ridleys.

Once hatched, olive ridleys will spend the vast majority of their life out in the open sea. Here, they forage for a range of food, including fish, jellyfish and algae. However, not much is known about this stage of the turtle's life histories.

When the time is right, olive ridleys will migrate for thousands of miles to reach the beach where they once hatched to lay eggs of their own. Males, characterised by their longer tail, wait in the shallows and attempt to mate with females as they make the arduous journey.

So, are you wondering when the best time to visit Costa Rica would be? Will the prospect of seeing thousands of sea turtles in the rainy season sway you? It's enough to persuade me!

2. Green Turtle

Jack with a green sea turtle in Cyprus

Green turtles are so called not because of the colour of their shell, but the layer of green, fatty tissue under their skin.

In Costa Rica, however, a sub-species of the green turtle can be found: tortuga negra - or black sea turtle. Unlike their close relatives, this sub-species of green turtle is named after its black shell.

Second only to the leatherback turtle, the green turtle is one of the largest sea turtles in the world. The largest one I measured was on a remote beach called Playa Cabuyal, in Northern Costa Rica. It measured 118 cm (shell length only).

You may think that taking measurements is rather intrusive and stressful for the turtle. But you'd be surprised.

When females begin laying eggs, they enter a trance-like state. They become hyper-focused, intent on depositing their future offspring. Only drastic movements will cause a turtle to abandon the egg-laying, and this is when we can collect measurements and biometrics.

After approximately 60 days, baby turtles hatch en-masse, flooding the beach with thousands upon thousands of the tiny reptiles. This is an anti-predatory strategy - after all, safety in numbers.

Young green turtles are omnivorous, preying on small crustaceans, molluscs and sea grass. However, once they reach adulthood, green turtles lead a vegetarian lifestyle. They feed heavily on seagrass and algae.

Green sea turtles are one of the longest lived vertebrate species in the world, reaching ages of over 70 years.

3. Leatherback Turtle

Leatherback's are the largest extant species of sea turtles

The leatherback turtle is a record breaker.

Not only is it the largest species of turtle in the world, with some measuring an astonishing 2 metres in length and over 900 kg in weight, it is also the deepest diver of all marine turtles.

Leatherback turtles have been recorded diving to depths of over 1,000 metres, where they hunt deep-ocean jellyfish.

Unlike other species of sea turtles, which have a hard shell, the leatherback, living up to its name, has a soft, leathery shell. Whilst diving, their flexible shell stores excess nitrogen and can help the leatherback adapt to the high pressure of the deep ocean.

In addition, leatherbacks have a high oxygen affinity. This means that they can store high quantities of oxygen in their blood and muscles, allowing them to stay submerged for several hours at any one time.

In Costa Rica, populations of leatherbacks are critically endangered. Once a regular sight in beaches such as Playa Grande, populations have now crashed by over 70%.

I worked with The Leatherback Trust - now one of our partners - which monitored populations of leatherbacks, as well as other sea turtle species. During peak season, just 7 leatherbacks were recorded in a season. 

With our conservation itinerary you could find yourself working alongside The Leatherback Trust, or other turtle conservation groups across Costa Rica.
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However, populations on the Caribbean side of Costa Rica remain stable. They can commonly be seen in Tortuguero National Park throughout February to August.

4. Hawksbill Turtle

Scientists collect data from hawksbill turtles to understand growth metrics

Named after their pointed, hawk-like beak, hawksbill sea turtles are one of the rarest turtle species found in Costa Rica - despite their global distribution around tropical coral reefs.

Their pointed beak allows them to forage a rather unique prey species - sponges. They are one of the few species that can survive primarily on these ancient invertebrates. The narrowness of their jaw allows the hawksbill to access otherwise hard to reach areas.

A resident population of hawksbills can be found in Golfo Dulce; a rare tropical fjord in Southwest Costa Rica. However, due to the deep waters of the fjord, the small size of the turtle and the conservation status, sightings are few and far between.

Fortunately, I had the privilege of recently working with the Latin American Sea Turtle organisation. Together, we collected data on the resident population of hawksbills in the Golfo Dulce. 

Today, the best spots to see wild hawksbills are along the Caribbean coastline, in places such as Cahuita, Gandoca and Tortuguero national Parks.

Despite their rarity, they are one of the most spectacular species of sea turtles. Their mottled shells are adorned with shades of amber, orange, olive, yellow, brown and red. Alongside the colourful patterns, hawksbill turtles have serrated edges to the posterior region of their shell.

Because of the uniqueness of their shells, hawksbill's are highly valuable and targeted for the use in "tortoise-shell" jewellery and accessories.
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A fully grown adult hawksbill can reach just 80 cm in length, making them one of the smallest extant species of sea turtle.

5. Loggerhead Turtle

Not to judge a book by its cover, but loggerhead turtles are rather peculiar looking.

As babies, they have a large head in comparison to its body, complete with large, bulging eyes. As it matures, they remain somewhat disproportionately large, giving rise to its namesake.

However, their large heads are an evolutionary adaptation, not some kind of genetic mutation. The large heads of a loggerhead turtle support powerful jaw muscles - the perfect weaponry to help crush their hard shelled prey of clams and sea urchins.

Whilst loggerheads are mostly sighted in the Mediterranean (where I have conducted research), small populations can be found on the Caribbean coast of Costa Rica.

Between the months of May to October, loggerhead turtles come ashore around the beaches of Tortuguero. Like the hawksbill, loggerhead turtles are quite a rare sight in Costa Rica.

Final Thoughts

Sea turtles have been roaming the world's oceans for millions of years. They are one of the oldest living vertebrate species living today.

In Costa Rica, 5 species of sea turtles can be found - all of which are threatened with extinction.

The most common sea turtle, the olive ridley, can be seen on the Pacific shores of Costa Rica in their hundreds of thousands at certain times of the year. 

Other species, such as the hawksbill and loggerhead, can be seen infrequently in small hotspots across the Caribbean coastline and a small fjord in the Puntarenas province.

In our next article, we'll be looking at some of the threats sea turtles in costa Rica are facing, as well as the work being done to safeguard future populations.