About Sea Turtles
Sea turtles are a group of reptiles more than 100 million years old, perfectly adapted to life in the ocean, where they play unique and crucial ecological roles. For example, they are vital for the functioning of coral reef ecosystems. Hawksbill turtles, whose main diet consists of sea sponges, help control sponge overgrowth on reefs. In this way, they directly influence the composition, structure, and biodiversity of these ecosystems.
Families and Species
Modern sea turtles are divided into two families: Dermochelyiidae, represented by the leatherback turtle (Dermochelys coriacea), and Cheloniidae, which includes six other species. Cheloniidae turtles are characterized by keratin plates covering a strong bony shell. In contrast, the leatherback turtle has a shell made of a thick, flexible layer of skin reinforced with thousands of small bony plates – an adaptation that allows deep diving in search of food.
Ancient. Beautiful. At risk.
Population Decline
Populations of all seven species of sea turtles are declining sharply. The situation is relatively better in the Atlantic Ocean, where beach protection programs are more common. In the Pacific Ocean, however, populations are dropping exponentially, and in the Indian Ocean many populations have already disappeared.
The threats they face are closely tied to their life cycle. During the terrestrial phase – which represents only a tiny fraction of their lives – females, eggs, and hatchlings are exposed to numerous dangers. Nest flooding by tides, predation, or even nest destruction by other turtles are all risks. While some of these threats are natural, human activity greatly intensifies them. Rising sea levels caused by climate change increase the risk of nest flooding. Introduced predators such as dogs and rats raid nests. Coastal development reduces available nesting beaches, and artificial lights from urban areas disorient hatchlings.
Population decline over recent decades.
Human Exploitation
The greatest problem in many regions remains the harvesting of turtle eggs and the killing of females for meat. Adult sea turtles have almost no natural predators in the ocean – the biggest threat to them is humans. Hawksbill turtles, in particular, have been hunted for their beautifully patterned shells, which are still illegally traded despite international bans.
Fishing, however, represents the leading cause of sea turtle mortality worldwide. Industrial fishing fleets not only deplete fish stocks but also kill countless non-target species (bycatch) – including turtles, marine mammals, birds, and sharks. Turtles get caught on baited hooks or entangled in nets. Some survive, but those trapped too deep often drown because they cannot reach the surface to breathe. The impact of these activities on turtle populations is enormous, and only recently has bycatch become a global conservation priority.
Life Cycle and Reproduction
Adult sea turtles migrate repeatedly between feeding grounds and nesting beaches, often thousands of kilometers apart. Because of the extreme energy demands and dangers of migration, turtles do not reproduce every year. When they do, males and females meet near the beaches where the females themselves once hatched. Each female lays several clutches of 60–100 eggs during a breeding season lasting about two months.
The sex of the hatchlings is determined by nest temperature: higher temperatures produce females, lower ones produce males. After hatching, the tiny turtles must quickly reach the sea and escape predator-rich coastal waters to find food and safety in deeper areas.
Sea turtles grow slowly, and their age of maturity varies by species, usually between 20 and 50 years.
