Sea Turtles

Sea turtles have been swimming the world’s oceans for around 110 million years! They belong to the same family as terrapins and tortoises, but sea turtles are adapted to life in the ocean. There are currently 7 known species and sea turtles are found in all oceans but the Polar Regions.

As reptiles they are ectotherms, meaning that they rely on environmental heat sources to control their body temperature. Sea turtles often swim at the ocean surface in shallow waters in order to sunbathe and warm themselves. They are also air breathers and must return to the surface regularly for oxygen; they are very efficient at refilling their lungs, doing it with one large explosive exhalation and rapid inhalation. They can hold their breath for several hours depending on their level of activity. So they can comfortably wedge themselves into the reef to get a good night's sleep.

Most sea turtles have a tough shell on their back to protect them from predators. The outer layers of the shell is covered in scales called scutes which are made of keratin. Keratin is the same substance that your fingernails, whale baleen and a rhino horns are made of. These scutes overlap and make the shell strong.

Scutes overlap which helps to make shells strong.

Baleen is the name given to these brush-like structures in a whale's mouth which they use to sieve small fish and crustaceans out of the water with.

Rhino horns are made from keratin, as are your fingernails!

Scutes overlap which helps to make shells strong.

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Scutes overlap which helps to make shells strong.

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Baleen is the name given to these brush-like structures in a whale's mouth which they use to sieve small fish and crustaceans out of the water with.

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Baleen is the name given to these brush-like structures in a whale's mouth which they use to sieve small fish and crustaceans out of the water with.

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Rhino horns are made from keratin, as are your fingernails!

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Rhino horns are made from keratin, as are your fingernails!

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Leatherback Sea Turtle

The largest species of sea turtle, the Leatherback, is the only soft shelled sea turtle species. Its soft shell allows it to dive to great depths; if it had a hard shell the pressure would crack it. Leatherbacks are also the largest species of sea turtle growing to over 2m! They visit British waters each summer to gorge themselves on delicious jellyfish. (Credit: U.S. Fish and Wildlife Service Southeast Region)

When adults, most sea turtles are omnivorous, which means they eat both meat and vegetation. They eat a wide range of animals and plants including insects, crustaceans, sponges, corals, sea anemones, starfish, seagrass and worms to name but a few. Sea turtles are well known for eating jellyfish and they are able to tolerant jellyfish stings. Sea turtles can even eat the deadly Box jellyfish!

Green sea turtles are a little different. When they are young hatchlings they are almost entirely carnivorous, feeding on small fish, squid and crustaceans, however when they get older they become herbivorous feeding entirely on seaweed, seagrass and algae. This diet turns the fat under their shell bright green which is how they got their name.

Sea turtles love to eat jellyfish!

Phoenix and Boris are SEA LIFE London's Green sea turtles.

Baby sea turtles are called hatchlings.

Sea turtles love to eat jellyfish!

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Sea turtles love to eat jellyfish!

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Phoenix and Boris are SEA LIFE London's Green sea turtles.

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Phoenix and Boris are SEA LIFE London's Green sea turtles.

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Baby sea turtles are called hatchlings.

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Baby sea turtles are called hatchlings.

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Reproduction

A pregnant female sea turtle will often return to the same beach she hatched on to lay her eggs, sometimes migrating thousands of miles to do so. Until recently nobody knew how they managed to find their way back to the same beach after so many years, but they have been found to have magnetite crystals in their head so they can detect the earth’s magnetic field. These crystals work like an inbuilt compass so that turtles can track where they are in the world! 

 

A female can lay up to 200 eggs at a time in a hole she has dug called a clutch. The eggs are soft and leathery so they don’t crack from the fall as she deposits them on top of each other in the hole. Once all the eggs are laid the female will cover them over with sand and leave. Dragging themselves up the beach and digging a big hole is no easy task for a large animal built for the ocean; the whole process is extremely exhausting for the females and they are very vulnerable to predators when they head back out to sea. They will not return to look after their young; the babies, known as hatchlings, will have to look after themselves from day one.

 

 

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The gender of the developing hatchlings is determined by the temperature in the clutch; if it is warmer they will be female, cooler male. This is one of the many reasons why climate change is a threat to turtles; if the planet warms up, there may not be enough males for the species to go on.

When the hatchlings are fully developed they will all hatch on mass. Thousands of baby turtles, around 5cm in length, will all emerge from clutches along a single beach and follow the brightest horizon to reach the ocean. In built-up areas street lighting often causes hatchlings to crawl towards land instead of the ocean.

It’s a perilous journey and many will be taken by foxes, seagulls, crabs, racoons and many other animals (even ants!). Once they reach the ocean more will be taken by sharks, fish, crocodiles, rays and many other predators. Less than 1% will make it to adulthood; starting out so small and defenceless in life is dangerous, but by overwhelming predators with a high volume of hatchlings at the same time, some can survive.

Once they reach the ocean, male sea turtles will not go back to the land again. Females will only return decades later (approx. 30) when they reach sexual maturity. It is this slow reproductive process that makes sea turtles so vulnerable to threats such as overfishing and plastic pollution.

Importance to Ecosystems

(Photo credit: P. Lindgren)

Sea turtles play an important role in keeping marine and land ecosystems healthy. Green sea turtles are one of the few creatures that eat sea grass. Sea grass must be constantly cut short to help it grow across the sea floor so without sea turtles grazing on it, sea grass beds would struggle to develop. These beds provide breeding grounds and nurseries for many species of fish, seahorses, shellfish and crustaceans. 

Hatched and unhatched eggs, and the bodies of hatclings that didn't make it to the sea, form an important source of nutrients for dune vegetation on beaches. When dune vegetation thrives, this in turn means the health of the entire beach and dune ecosystems thrives too. Stronger vegetation and root systems help to hold the sand in the dunes and protect the beach from erosion. A great example of how all ecosystems, marine and terrestrial, are interlinked!

Threats

Plastic Pollution

Plastic pollution is a huge problem for all marine life. Scientists estimate that up to 26 million tons of plastic waste end up in the ocean each year, killing millions of marine creatures. Drifting through the world’s oceans are hundreds of tons of plastic that will not fully break down and disappear for centuries.

Around 80% of this plastic comes from the land as litter is carried out to sea by rivers and blown by the wind from landfill into the ocean. The other 20% comes from ships at sea.

One of the biggest threats to sea turtles are plastic bags which often get blown into the ocean and look a lot like jellyfish. Turtles regularly try to eat plastic bags and choke on them.

So, how can we help?

 

Get yourself some reusable string, canvas or cotton bags instead. (Photo credit: Jonasek22)

Avoid plastic packaging where possible. Reuse your plastic products as many times as possible. Recycle everything that you can!

When products come with too much, unnecessary packaging, be sure to complain!

Get yourself some reusable string, canvas or cotton bags instead. (Photo credit: Jonasek22)

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Get yourself some reusable string, canvas or cotton bags instead. (Photo credit: Jonasek22)

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Avoid plastic packaging where possible. Reuse your plastic products as many times as possible. Recycle everything that you can!

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Avoid plastic packaging where possible. Reuse your plastic products as many times as possible. Recycle everything that you can!

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When products come with too much, unnecessary packaging, be sure to complain!

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When products come with too much, unnecessary packaging, be sure to complain!

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You can take part in large organised beach cleans to stop plastic pollution reaching the ocean; contact your closest coastal SEA LIFE site or the Marine Conservation Society to find one near you. Or you can simply do your own mini, five minute beach clean every time you go to the seaside.

If you don't live near the ocean you can still help! Rivers and streams carry plastic pollution out to sea. Here at SEA LIFE London we often join local charity Thames21 to clean areas of Thames riverbank of plastic.

Visit the SEA LIFE Trust page for more information on plastic pollution and top tips of ways you can help.

You can take part in large organised beach cleans to stop plastic pollution reaching the ocean; contact your closest coastal SEA LIFE site or the Marine Conservation Society to find one near you. Or you can simply do your own mini, five minute beach clean every time you go to the seaside.

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You can take part in large organised beach cleans to stop plastic pollution reaching the ocean; contact your closest coastal SEA LIFE site or the Marine Conservation Society to find one near you. Or you can simply do your own mini, five minute beach clean every time you go to the seaside.

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If you don't live near the ocean you can still help! Rivers and streams carry plastic pollution out to sea. Here at SEA LIFE London we often join local charity Thames21 to clean areas of Thames riverbank of plastic.

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If you don't live near the ocean you can still help! Rivers and streams carry plastic pollution out to sea. Here at SEA LIFE London we often join local charity Thames21 to clean areas of Thames riverbank of plastic.

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Visit the SEA LIFE Trust page for more information on plastic pollution and top tips of ways you can help.

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Visit the SEA LIFE Trust page for more information on plastic pollution and top tips of ways you can help.

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Bycatch

Sea turtles are often caught by accident by fishing boats as bycatch. Examples of fishing methods which have particularly high sea turtle bycatch levels are:

  • Long-lining is a method used to catch large predatory species such as swordfish, marlin and tuna. It involves letting out up to 60 miles of floating lines with baited hooks hanging at intervals. This fishing method kills millions of unwanted species including turtles but also sharks, sea birds, seals and more.
  • FAD purse seine fishing tuna is a method used widely to catch tuna. A Fish Aggregation Device (FAD) is an object that is left floating on the surface of the water to attract small fish looking for refuge. These small fish attract bigger fish which prey on them and these in turn attract bigger predators and so on. After a period of time an FAD floating in the ocean attracts a wealth of marine life from tuna to sea turtles, to sharks and seals. Enormous nets are dropped around the FADs in a circle and draw together at the bottom like a drawstring purse, indiscriminately catching everything. You will often see tuna that has been caught using this method labelled as 'dolphin friendly', however it is not sea turtle, shark, seal, bird etc. friendly.

So, how can we help?

We have free MCS Good Fish Guides available for all of our guests! These booklets help you to make sustainable choices when buying seafood and therefore help to protect all kinds of marine life including sea turtles.

Marine Stewardship Certification is one of the most reliable labels to look for when choosing sustainable seafood and MSC certified products are readily available in many supermarkets and restaurants around the world! Be wary of vague 'sustainably sourced' and 'responsibly fished' claims on packaging and restaurant menus; when not backed up with any explanation of what makes the product sustainable, or any actual certification, these labels can too often prove meaningless.

If you are buying tuna fish, ensure it has been caught using the 'pole and line' method which has no bycatch and allows fishermen to easily return undersized fish to the ocean. You can also often find MSC certified tuna which has been responsibly sourced. (Photo credit: Paul Hilton) 

We have free MCS Good Fish Guides available for all of our guests! These booklets help you to make sustainable choices when buying seafood and therefore help to protect all kinds of marine life including sea turtles.

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We have free MCS Good Fish Guides available for all of our guests! These booklets help you to make sustainable choices when buying seafood and therefore help to protect all kinds of marine life including sea turtles.

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Marine Stewardship Certification is one of the most reliable labels to look for when choosing sustainable seafood and MSC certified products are readily available in many supermarkets and restaurants around the world! Be wary of vague 'sustainably sourced' and 'responsibly fished' claims on packaging and restaurant menus; when not backed up with any explanation of what makes the product sustainable, or any actual certification, these labels can too often prove meaningless.

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Marine Stewardship Certification is one of the most reliable labels to look for when choosing sustainable seafood and MSC certified products are readily available in many supermarkets and restaurants around the world! Be wary of vague 'sustainably sourced' and 'responsibly fished' claims on packaging and restaurant menus; when not backed up with any explanation of what makes the product sustainable, or any actual certification, these labels can too often prove meaningless.

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If you are buying tuna fish, ensure it has been caught using the 'pole and line' method which has no bycatch and allows fishermen to easily return undersized fish to the ocean. You can also often find MSC certified tuna which has been responsibly sourced. (Photo credit: Paul Hilton) 

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If you are buying tuna fish, ensure it has been caught using the 'pole and line' method which has no bycatch and allows fishermen to easily return undersized fish to the ocean. You can also often find MSC certified tuna which has been responsibly sourced. (Photo credit: Paul Hilton) 

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Prawn Farming

Mangroves are an important habitat for sea turtles, but today less than half of the world’s original mangrove forest cover remains. In countries such as America, mangrove forests are being cleared out almost twice as fast as tropical rainforests.

There are many reasons for mangrove destruction including development for tourism, agricultural land and harbours. They are over-harvested for wood, overfished and polluted. However by far the biggest threat to mangroves is shrimp and prawn farming; as much as 50% of the mangrove destruction in recent years is due to clear cutting for shrimp and prawn farms.

These shrimp and prawns are being bred to supply many countries around the world, with the leading consumers including the USA, Japan and Europe (including the UK). When a farming project has run its course the land is simply abandoned; the salinity levels leave it useless for other agriculture. Hundreds of thousands of farmed hectares of shrimp and prawn farmland now lie abandoned because of disease and pollution.

So, how can we help?

Unless they have been organically farmed, they have probably come from farms built on deforested mangrove. Look for MSC certified prawns!

Find out more about mangroves and what you can do to help protect them.

Unless they have been organically farmed, they have probably come from farms built on deforested mangrove. Look for MSC certified prawns!

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Unless they have been organically farmed, they have probably come from farms built on deforested mangrove. Look for MSC certified prawns!

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Find out more about mangroves and what you can do to help protect them.

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Find out more about mangroves and what you can do to help protect them.

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Poaching and the Curio Trade

In some parts of the world turtle meat and eggs are a delicacy and so turtle nests are raided for eggs and hatchlings whilst adult turtles are hunted. Sea turtle shells are often used to make jewellery, ornaments and other knick-knacks which are often sold to tourists. Hawksbill sea turtle shells are particularly sought after because of their stunning marbled quality. Products made from sea turtle shell are usually labelled 'tortoiseshell'.

So, how can we help?

Jewellery, hair accessories, guitar picks, knitting needles, ornamental boxes, frames for glasses and musical instruments are a few examples of products which can be made from sea turtle shell.

If you spot anything on the menu that contains sea turtle or turtle eggs, for example Chinese turtle soup, then don't be tempted to try it. (Photo credit: Chensiyuan)

Jewellery, hair accessories, guitar picks, knitting needles, ornamental boxes, frames for glasses and musical instruments are a few examples of products which can be made from sea turtle shell.

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Jewellery, hair accessories, guitar picks, knitting needles, ornamental boxes, frames for glasses and musical instruments are a few examples of products which can be made from sea turtle shell.

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If you spot anything on the menu that contains sea turtle or turtle eggs, for example Chinese turtle soup, then don't be tempted to try it. (Photo credit: Chensiyuan)

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If you spot anything on the menu that contains sea turtle or turtle eggs, for example Chinese turtle soup, then don't be tempted to try it. (Photo credit: Chensiyuan)

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Boat Strikes

Each year many sea turtles are injured or killed after being struck by boats and jet skis. If hit, turtle shells are often cracked and can get an air bubble trapped within so turtles can no longer dive to find food or safety.

Sometimes extreme weather conditions can cause sea turtles to lose their way. Oil spills are also a huge threat to sea turtles as they are to a whole host of other marine species.

SEA LIFE sites often rescue, rehabilitate and where possible release lost, sick and injured sea turtles. 

Find out more:

 

 

Find out what happens to sea turtles that have been tagged and released by SEA LIFE sites in Australia and New Zealand with support from the SEA LIFE Trust.

Follow the SEA LIFE Trust on facebook to keep up with their work and find out more about marine conservation.

£5 from every Turtle Feed Experience goes to the SEA LIFE Trust!

Find out what happens to sea turtles that have been tagged and released by SEA LIFE sites in Australia and New Zealand with support from the SEA LIFE Trust.

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Find out what happens to sea turtles that have been tagged and released by SEA LIFE sites in Australia and New Zealand with support from the SEA LIFE Trust.

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Follow the SEA LIFE Trust on facebook to keep up with their work and find out more about marine conservation.

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Follow the SEA LIFE Trust on facebook to keep up with their work and find out more about marine conservation.

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£5 from every Turtle Feed Experience goes to the SEA LIFE Trust!

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£5 from every Turtle Feed Experience goes to the SEA LIFE Trust!

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