How Fast Do Different Sea Turtles Grow? [Growth Rate]

The information is current and up-to-date in accordance with the latest veterinarian research.

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Sea turtles are larger than any aquatic or semi-aquatic turtles. So, it goes without saying that this species must have a faster growth rate.

Baby sea turtles go through the fastest growth, and the rate slows down once the creatures hit maturity. The green sea turtles experience 4 to 5 cm/year growth during the early age. This growth rate is 11.8 and 32 cm/year for loggerhead sea turtles and leatherback sea turtles, respectively.

Well, there are flaws or limitations in each growth measuring technology. For example, skeletochonology and mark recapture can show errors in the results. Also, some studies are a specific area or condition based. Keep these factors in mind when going through the below article.

Growth Rate of Different Sea Turtles

I have come across several studies when researching the growth of sea turtle species. Each study is focused on 1/2 specific factors. It means these papers share no universal growth rate of sea turtles and include some limitations.

But the good part is we can make an educated guess from the available data. Such as,

Green Sea Turtle Growth Rate

Baby green sea turtles are only 2 inches (5 cm). But these turtles grow 3 – 4 feet (83 – 114 cm) with 300 – 350 pounds (136 – 159 kgs) when they are adults.

You can not say how long it takes for complete growth. Generally, green sea turtles gain maturity at 26 – 40. By this age, the turtles reach absolute carapace growth, and the development process slows down after maturity.

One experiment on Hawaiian green sea turtles helps us to assume the approximate growth rate of the species. The researchers concluded that the mean growth rate of the baby and juvenile Hawaiian green sea turtles is 4/5 cm per year. This is quite healthy as the turtles need fast development during the early days.

However, the mean growth rate drops to 2 cm per year when the turtles reach 10 years. The study also shows that the adult green sea turtles with 90 – 100 cm carapace exhibit the least growth of 0.6 cm per year. It means the carapace growth is declining with increasing age.

Loggerhead Sea Turtle Growth Rate

Typically, adult loggerhead sea turtles are 2.5 – 3.5 feet (80 – 110 cm) in size. They weigh around 250 pounds (113 kgs). But some loggerhead turtles up to 1000 pounds are recorded over time.

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The baby loggerhead turtles are not more than 2.3 inches (6 cm). They experience a faster development in the early days, and the growth rate slows down as the creatures hit sexual maturity. 25 – 35 is the age range when the loggerhead turtles become sexually active.

In 2009, a group of Italian researchers published their findings on the age size and growth rates of juvenile Loggerhead sea turtles. Their study is only limited to the loggerhead turtles of the Mediterranean Sea, specifically, Italian water.

As per the paper, the loggerhead hatchlings experience a growth rate of 11.8 cm/ year for the first 6 months. The rate drops to 3.6 cm/year for the next 2.5 – 3.5 years.

Another study was conducted on the loggerhead sea turtles of the Western North Atlantic. The paper concludes that these turtles take 16 – 23 years to grow 50 cm to 80 cm. Again, during the early or juvenile ages, the estimated growth rate of loggerhead turtles is 7.3 cm per year.

The growth rate difference between the Atlantic and Medeterrian loggerhead sea turtles is due to geography, diet, or error.

Flatback Sea Turtle Growth Rate

The baby flatback sea turtles are born large, approximately 2.4 inches (6 cm). So, these hatchlings are born with a larger carapace than other subspecies. But their adult size is not more than 2.4 to 3.25 feet (73 – 99 cm). Even their body weight barely crosses 198 pounds (90 kgs).

To address the growth rate, a group of scientists initiated research on Australian flatback sea turtles. They collected rare bone samples and conducted the experiment by skeletochronology.

As per the data, the flatback sea turtle hatchlings experience faster growth. For example, the babies grow from 6 cm to 10 cm (approximately) within the first 7 weeks. Likewise, the mean SCL (straight carapace length) of the flatback sea turtles is 12.7 cm by 11 weeks and 12.6 cm by 19 weeks.

They have also concluded that mature flatback sea turtles go through minimum growth. As per the report, the mother turtles experience even slower carapace development prior to the first nesting (for 1 – 10 years).

Generally, flatback sea turtles reach sexual maturity between the ages of 7 to 50. The curved carapace length of the nesting females is between 75 to 95 cm.

So, it is assumed that flatback sea turtles, both male and female, become sexually active when they hit this curved carapace length.

Hawksbill Sea Turtle Growth Rate

Usually, the hawksbill sea turtle hatchlings are born small, 1 – 2 inches in length, and 0.85 ounces (24g). When adults, these creatures get a carapace size of 2 – 3.8 feet (60 to 110 cm). Their adult self can grow up to 150 pounds (68 kgs).

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A research paper from 2014 concludes that all hawksbill turtles experience a growth rate of an average of 9.3 cm per year. The weight growth of the subspecies is, on average, 3.9 kg per year.

As per the report, the majority of hawksbill sea turtles grow faster in the first 4 – 5 years (22 to 60 cm). The mean adult size for these turtles is 70 cm, which they gain within 20 -25 years.

Apparently, the captive hawksbill sea turtles can experience a faster growth rate, 12 cm per year. But the data resources are limited for a detailed review.

Leatherback Sea Turtles Growth Rate

Well, leatherback sea turtles are the largest of the 7 sea turtle subspecies. These majestic creatures can grow up to 10 feet (305 cm) and weigh over 2000 pounds (900 kgs). When born, the leatherback sea turtles are around 2 – 3 inches and develop this gigantic body over the years.

A research team worked on the growth rate of leatherback sea turtles in captivity and the wild. The group observed several turtles in captivity for over 2 years.

These turtles had a stunning growth rate of an average of 32 cm per year (approximately). The hatchlings with 6 cm (approx) length developed a carapace of 72 cm (largest turtle) in 2 years.

Of course, a 32 cm per year growth rate is huge, and not every leatherback sea turtle experiences the same development. Also, the turtles under constant observation may show better growth because of the extra care.

Anyhow, the leatherback sea turtles will reach adult size soon. The creatures gain sexual maturity at an early age, 9 – 20, and the growth rate falls after that.

Kemp’s Ridley Sea Turtle Growth Rate

Among all the sea turtle subspecies, Kemp’s ridley sea turtles are the smallest. In adulthood, the creatures reach around 2.6 feet (82 cm) and weigh up to 100 pounds (45 kg). Even the hatchling size is not more than a dollar coin with 0.5 ounces (14 g) body weight.

A recent study reveals somewhat the approximate growth rate of Kemp’s ridley sea turtles.

Scientists have discovered that the annual growth rate of Gulf Mexican Kemp’s ridley sea turtles is 3.6 to 5.4 cm per year. It is definitely less than the sea turtles of the Atlantic Ocean ones (5.9 – 8.8 cm per year).

The report also shows how the growth rate of Kemp’s ridley differs with age. For example, the development for sea turtles with 30 – 40 cm carapace length is 4.6 cm per year. Again, the rate is 6.2 and 4.6 cm per year for Kemp’s ridley sea turtles with 40 – 50 and 50 – 60 cm, respectively.

Moreover, the sexual maturity age of the Kemp’s ridley sea turtle is 11 – 16. An assumption is that a turtle with 18.8 to 72 cm CCL is somewhat between 2 to 15 years old.

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Olive Ridley Sea Turtle Growth Rate

The Olive ridley sea turtles have similar growth to the Kemp’s ridley sea turtles. Babies of these subspecies are born about 1.5 to 2 inches, and the adults have a carapace up to 2.5 feet (76 cm). Their weight is, on average, 100 pounds.

A study in 2006 concluded that 50% of olive ridley sea turtles mature at age 13. The turtles with a 35 – 40 cm carapace length are around 10 years old. Likewise, if the length exceeds 60 cm, the age of the creatures is approximately 13 – 14 years.

Growth Chart Of Sea Turtles

As mentioned, the above-stated information is not universal but an estimated guess. You can also develop the idea of the physical development of these turtles by assessing their size, maturity age, and lifespan. See if the below chart comes of any help,

Sea Turtle SubspeciesHatchlings SizeAdult SizeMaturity AgeTotal Lifespan
Green Sea Turtle2 inches3 to 5 feet26 to 40 years80 to 100 years
Leatherback Sea Turtle2 to 3 inches4 to 6.5 feet9 to 20 years30 to 50 years
Loggerhead Sea Turtle2.3 inches2.5 to 3.6 feet25 to 35 years70 – 80 years++
Kemp’s Ridley Sea Turtle1 inch1.7 to 2.6 feet11 to 16 years30 to 50 years
Olive Ridley Sea Turtle1.5 to 2 inches2 to 2.5 feet13 – 14 yearsUp to 50 years
Hawksbill Sea Turtle1 to 2 inches2 to 3.8 feet20 – 35 years50 – 60 years
Flatback Sea Turtle2.4 inches2.4 to 3.25 feet7 to 50 yearsUp to 100 years

Sea Turtle Growth Factors

It is quite difficult to process the actual growth rate of sea turtles due to their mysterious living style. Yet, the researchers have tried to pull off an estimated guess by working on several concentrated areas.

But remember, the growth rate of turtles from one area can be different from other regions. So, it indicates that the physical development of these sea turtles is not constant and depends on several factors. For example,

1. Area Status:

The growth rate of sea turtles significantly depends on the region the creatures live in. If the turtles are around a foraging ground, they will experience fast development. It is because they have plenty of food around them.

2. Captive or Wild:

Research centers sometimes volunteer to hatch the sea turtle clutches and raise the babies for a few years. Again, the teams may take care of the wounded turtles or healthy turtles for research purposes. As the turtles in captivity get regular meals and extra attention, they may go through healthy and fast physical development.

3. Body Size or Age:

All research studies have indicated that the growth process depends on the carapace length or age, to be particular. You can expect a high growth rate for the smaller turtles. The development process slows down as the turtles grow older.

4. Genetics:

Of course, you can not expect all the leatherback sea turtles to grow 7 feet. Some turtles stay small because of genetic disorders. Similarly, a few of the subspecies can reach 10 feet of growth.

Before You Go

Don’t you want to know the growth rate of your regular pet turtles? Yes, they have an overall development different from sea turtles. The attached article below will offer you a clear idea of the growth process of aquatic or semi-aquatic turtles.

Turtle Growth Chart: How Fast Do Turtles Grow? 

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About Author

Muntaseer Rahman started keeping pet turtles back in 2013. He also owns the largest Turtle & Tortoise Facebook community in Bangladesh. These days he is mostly active on Facebook.

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