Vegan Life investigates how human activities are pushing species like the hawksbill turtle closer to extinction
There are seven species of sea turtle and all are considered to be threatened. However, the hawksbill turtle, found in the tropics of the Atlantic, Pacific and Indian Oceans, is the only species that is critically endangered. They have a hooked beak, reminiscent of a hawk, which they use to eat corals and sponges. Adult hawksbills travel enormous distances to nesting grounds and can lay up to 180 eggs which incubate in the warm sand for two months before the baby turtles emerge. Watching hundreds of hatchlings struggle across a sandy beach before plunging into the ocean must be one of earth’s cutest phenomena and is something that we want to see continue into the future.
- According to the International Union for Conservation of Nature (IUCN), the population of mature nesting females has declined by over eighty per cent over the last three generations of hawksbills and the species has now been listed as critically endangered.
- The main reasons for the decline in this species are; accidental capture in fishing nets, consumption of hawksbill turtle eggs and poaching for their carapaces (shells). The hawksbill is the only turtle poached for tortoiseshell and, despite the trade being banned by CITES in 1973, there is still an illegal market in some areas of the world.
- Light pollution is also a substantial danger for sea turtles. Hatchlings can confuse light pollution for the reflection of the moon/stars on the ocean and this can disorientate the youngsters leading them towards towns and campfires, not the shoreline.
- Juvenile hawksbill turtles have a heart-shaped carapace (shell) which becomes more tear-shaped as they age. Their distinctive shell pattern is fashionable but make sure you are buying synthetic materials, particularly when purchasing overseas. •Sea turtles can see in colour which allows them to see their food and potential predators. They can see underwater in more clarity than on land.
- Turtles don’t have nostrils. Instead, bumps under their chins called barbels allow them to locate food, through their olfactory sense, from great distances.
- Hawksbills are omnivores but primarily eat algae. They also eat molluscs, crustaceans, fish and sponges. Far from the artificial bathroom variety, natural sea sponges are multicellular animals, not plants, and provide turtles with proteins. Sea sponges are one of earth’s oldest and most successful animals; in some areas of the world hawksbills primary diet is sponge. It has been reported that in these areas they can eat in excess of 500kg of sponge per annum.
- Males and females are similar sizes which can make it tricky to tell the difference, although there are a few subtle differences. Males have curved claws on their front flippers and tend to have slightly longer tails — as long as they are over three-years-old!
- Most sea turtles are solitary animals, except for their bi/tri-annual meetings to reproduce. Environmental indicators such as lengthening of the day and increases in temperature trigger the turtles’ instinct to mate.
- Incredibly, turtles have a mechanism, known as temperature-dependent sex determination (TSD), which causes the gender of hatchlings to be governed by the temperature of the ocean. Generally, female turtles are more likely to develop in higher temperatures whereas males prefer it a little cooler. A change in temperature as slight as one degree Celsius can affect the hatchlings and turtles are therefore very particular about the temperatures at which they reproduce. TSD is not confined to turtles, many other reptiles and the majority of fish are highly receptive to small temperature changes.
- The nesting season usually occurs between April and November.