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Animals · Seas and oceans

Sea turtle

Caretta caretta

Returns to nest on its birth beach

A female sea turtle uses her hind legs to dig the deep hole where she will lay her eggs.
A female sea turtle uses her hind legs to dig the deep hole where she will lay her eggs.
  • Status: Threatened
  • Temperate seas of the Atlantic, Mediterranean, Black Sea, Indian, and Pacific

Numbers

Weight
287 lbintermediate value of the range from 220 to 350 lb; the Mediterranean subspecies is smaller and exceptionally reaches 310 lb
Length
43 inintermediate value of the range from 31 to 55 inches; at birth it measures about two inches
Lifespan
50 yearsfrom 50 to over 80 years in the wild
Speed in water
22 mphachieved with synchronous movement of the front flippers
Eggs per nest
200 eggsthe ritual can be repeated several times in the same season, at intervals of 10 to 20 days
First swim without stopping
24 hoursperformed by hatchlings to move away from the coast and reach the continental shelf

Ten fun facts

  1. at birth it measures about two inches and as an adult it can reach fifty-five inches, twenty-eight times as much.

  2. young turtles have two claws on their front flippers, which are reduced to just one in adults.

  3. plastic bags mistaken for jellyfish, bottle caps, hooks, and lines mistaken for seaweed have been found in their stomachs.

  4. to break out of its shell it uses an egg tooth, a structure that is absorbed within a couple of weeks.

  5. hatchlings orient themselves toward the brightest light source within an arc of fifteen degrees above the horizon.

  6. a female can nest several times in the same season, at intervals of ten to twenty days.

  7. females mate with multiple males and store sperm to fertilize subsequent clutches during the same nesting season.

  8. incubation lasts between 42 and 65 days, but in one case of late nesting it reached 90 days.

  9. global warming can skew the sex ratio of hatchlings up to ninety-nine females for every single male.

  10. off the Capo Spartivento lighthouse in Calabria, hundreds of individuals of similar age live together before their big migration.

The quiz answers

The first one is the question printed in your book: here is the answer. The other four are extra.

Question 1 of 5★ this one is in your book

What determines the sex of sea turtle hatchlings?

Question 2 of 5

How many eggs can a female lay in a single nest?

Question 3 of 5

Why are city lights dangerous for hatchlings?

Question 4 of 5

What is the dark period for this species?

Question 5 of 5

Why are plastic bags found inside their stomachs?

Try it yourself

Experiment 1

Pick up a ping-pong ball. It is the size of a sea turtle egg. Now imagine two hundred of them packed into the same sandy nest.

Experiment 2

Stand in your yard in the dark and see which light you turn toward. Hatchlings do the exact same thing, and bright city lights trick them.

Experiment 3

Mark two inches and then fifty-five inches on a paper ribbon. That shows how much a sea turtle grows from hatching all the way to adulthood.

Data from Wikidata (Q192095) and Wikipedia (Loggerhead sea turtle).