The natural world shows an incredible range of life forms of all different sizes and appearances, adaptations and behaviours. Yet, among this remarkable diversity, some animals still cause identification issues because of their similarities. This article will explain the differences between the different types of turtles around the world and discuss which ones you can find in the Algarve and throughout Portugal.
Turtle is a term used to describe a group of animals, reptiles of the order Testudines. This order includes sea turtles, freshwater turtles and tortoises. In common, they all share the unique characteristic of having their bodies enclosed in a bony or cartilaginous carapace.
Sea turtles
Sea turtles spend most of their lives in open seas. They have roamed our oceans for 100 million years and are perfectly adapted for aquatic life. Their limbs are not legs but fins that they use to swim. They can hold their breath for long periods of time and feed on a variety of prey, such as fish, jellyfish, seagrass and algae. Their main threats come from predators, such as sharks and orcas, illegal fishing, bycatch, pollution and beach strandings.
Among the seven species of marine turtle is the colossal leatherback turtle (Dermochelys coriacea), so-named for its soft rubbery shell. Leatherbacks can grow over two metres in length and weigh a whopping 900 kilograms. These formidable creatures can dive a mile deep and hold their breath for 85 minutes. Their annual migration takes them tens of thousands of miles around the oceans and, for females, ultimately back to the beach where they were born, where they lay impressive 100-egg clutches to secure the next generations.
Although sea turtles do not nest in Portugal, sightings of loggerheads, leatherbacks and green turtles are frequent along the Portuguese coast. The longest-living of the sea turtles are the green turtles which can live more than 80 years.
Tortoises
Land turtles, or tortoises, are terrestrial animals. They cannot swim and will only stand by the edge of the water to drink or cool down. If in deep water, they risk drowning as they cannot hold their breath underwater. Tortoises are slow-moving creatures that walk on four legs and are mainly vegetarian, feeding on a variety of plants and fruits. Among the 50 species of tortoises are the impressive giant Galapagos tortoises, famous for the study Charles Darwin published after his voyage aboard the HMS Beagle in 1831. Worldwide, there are around fifty different species of tortoises, including five that live in the Mediterranean region, but no land turtles live in Portugal, so you are only likely to see them if they are kept as pets.
Freshwater turtles
Terrapins, or freshwater turtles, are the spanner in the works, they are neither sea turtles or land turtles. These are a group of smaller turtles that live in fresh or brackish water systems and show distinct behavior and adaptations, such as having legs with partial webbed feet. They are also referred to as pond turtles or pond sliders. In Portugal, there are two endemic species: the Mediterranean pond turtle (Mauremys leprosa) and the European pond turtle (Emys orbicularis).
Similar in size, distribution and behaviour, the European pond turtle can grow to 18 cm in length and has a distinctive dark shell with yellow markings. Their Mediterranean cousin is bigger and more common in Portugal. It can grow to 25 cm in length and has a more discrete brownish-green appearance.
Both species feed on pond vegetation, invertebrates, insects, larvae and the occasional unaware fish. During cold winters, they can decide to hibernate. This is a strategy used by many animals to endure tougher winter times. Being cold-blooded animals, they rely on the sun to warm up and activate their metabolism. As such, it is no surprise that in the north of Portugal, this behavior is more frequent than in the south. The balmy temperatures of southern Portugal and the availability of sunshine mean that our resident terrapins in the Algarve do not often need to hibernate. When they do, the hibernation only lasts for a couple of months. These animals live around 30–40 years in the wild.
The main threats to our resident terrapins are illegal catching, predation from wild and domestic animals, and competition from exotic pond turtles. American-native species of terrapins were once a common pet in Portugal. Due to their longevity, many were released into natural waterways, where they found ideal conditions to thrive. Bigger, and with faster breeding cycles, they can quickly overcome the native species wherever they are introduced.
Native or exotic species, they all seem to enjoy basking in the sun, perched on rocks or tree branches over the water.
This ancient and adaptive species proves the moral of the children’s fable, The Tortoise and the Hare. Slow and steady wins the race!
