Crete is one of the most important places for the reproduction of the threatened loggerhead sea turtle (Caretta caretta), which is very famous throughout Greece. However, there are more sea turtle species found in the seas of Crete, which do not nest on the island. These are the green turtle, the leatherback turtle and the hawksbill sea turtle. All sea turtles have lungs, but can hold their breath for a long period under water.
Loggerhead sea turtle (Caretta caretta)
The loggerhead sea turtle (scient. Caretta caretta) is the most important sea turtle species of Greece, which is strictly protected by the Greek laws. In Greece, two organizations are involved in the protection of sea turtles, namely ARCHELON and MEDASSET, actually doing a great job.
The caretta turtle has a hard shell with 5 scutes on each side and its length extends to 100-120cm. Its weight usually reaches 100-150kg, but sometimes exceeds 450kg and the turtle lifespan is 47-67 years. It feeds mainly on jellyfish, molluscs, crustaceans, and rarely with algae. Unfortunately, a large number of turtles lose their life by swallowing plastic bags, confusing them with jellyfish.
Crete is one of the most important places for Caretta caretta breeding, as hundreds of loggerhead turtles lay their eggs on the island’s sandy beaches every summer. That's why associations for the protection of the sea turtles operate in the northern beaches of Chania and Rethymno cities, and in the Gulf of Messara, where the birthrates are higher than in other beaches of the island.
The female turtle approach the shores of Crete only for giving birth, every 2-4 years, from May to September. This is the time when beaches are filled with people. Once it finds a beach with no lights, it comes out in darkness and gives birth to 20-200 eggs, which are buried in the sand. When eggs hatch (after 2 months) the young turtles head to the sea. The female turtles live in the open sea till they become mature and return to the same beach to lay their eggs.
The problem with the life cycle of turtles is that the deterioration or destruction of the beach where they were born makes them actually incapable of reproduction (as they always lay their eggs on the same beach). For this reason, on beaches where turtles usually reproduce, it is not allowed to use lights, speakers, driving in the sand and walking in the evening, so as not to disturb turtles.
In Crete, turtles lay their eggs on all the sandy beaches of the island, so it is advisable to avoid evening walks on the beach during these hours. Also, if you locate a nest, you must call the relevant association and mark the spot temporarily, so as to avoid walking there. When informed, the association ARCHELON places metal cages over the nest. Also, for those interested, ARCHELON accepts donations and volunteers to support the association’s activities.
Leatherback turtle (Dermochelys coriacea)
The leatherback turtle (scient. Dermochelys coriacea) is the largest reptile in the world, with its shell growing up to 250cm and its weight, sometimes, exceeding 900kg. Infrequent appearances of the species have been reported in Greece (and in Crete), while there has not been reported any case of breeding on Greek beaches.
The leatherback turtle takes its name after its shell, covered by thick leather, rather than hard scutes, as the other sea turtle species. It lives permanently in the sea, usually in very deep and cold waters (up to 1200m depth), where it feeds on jellyfish and invertebrates. Its blades remind of paddles, helping it move very fast and to travel vast distances.
Like other turtles, the leatherback female turtles come ashore every 1-4 years just to give birth. The females dig a deep pit in the sand and lay 80-120 eggs therein, up to 12 times in the same breeding season. The buried eggs hatch after about 2 months.
Unfortunately, thousands of leatherback sea turtles lose their lives every year, after eating plastic bags that look like their favorite food, jellyfish.
Green Sea Turtle (Chelonia mydas)
The green sea turtle (scient. Chelonia mydas) has been met very rarely in the Greek seas and there are no indications for nesting on Greek shores. It is also found rarely off the Cretan seas and is the largest sea turtle with hard shell in the world.
It is the only herbivorous sea turtle, feeding primarily on algae. Its name does not come from the color of the turtle, but the color of its fat due to its algae-based diet.
It has a hard carapace with 4 scutes, with beautiful black, gray, brown and yellow shades, while it has a relatively small head. Its length can exceed 120cm, its weight usually reaches 100-150kg, and can live up to 80 years.
It lives permanently in the sea and the females come out on the sandy beach, where they were born, every 2-5 years, to lay 50-240 eggs. The eggs hatch after approximately 2-2.5 months. In the Mediterranean Sea, the green turtles breed in the eastern coasts (south-eastern Turkey, Cyprus).
This species is seriously threatened with extinction worldwide, as it is hunted by humans for its flesh. Moreover, many newborn turtle lose their life after swallowing plastic bags, considering them as food.
Hawksbill sea turtle (Eretmochelys imbricata)
The hawksbill sea turtle (scient. Eretmochelys imbricata) is an endangered sea turtle species found primarily in tropical seas. Some of them (very few) have been met in the open sea south of Crete and in other Mediterranean areas.
The hawksbill sea turtle is perhaps the most beautiful sea turtle and is named “tileturtle” by Greeks because its shell is composed of scutes that resemble tiles. The carapace has a length of up to 110cm and weighs 125kg. It feeds mainly on jellyfish and other marine invertebrates. However it is omnivorous species, as the juvenile turtles seem to prefer vegetable food.
Females approach the coasts every 2-6 years, digging deep pits into the sand and lay 50-200 eggs, up to 4 times in the same reproductive period. The eggs hatch after about 2 months.
The hawksbill sea turtles are eaten in some countries. Moreover, their carapace is the main source of articles of natural celluloid. Hence, fishermen often kill them or remove their carapaces while still alive. These practices threaten E. imbricata populations with extinction.