The shell of a sea turtle holds the history of the ocean like the annual rings of a tree

Sea turtle shells are made up of hard plates called scutes that grow in layers throughout their lives.

Each new layer

• retains chemical traces of the environment
• reflects the turtle's nutrition
• records changes in ocean conditions

In effect, the shell "records" the life of the animal and the environment around it.

Details

Scientists examined the shells of 24 sea turtles and separated them into very thin layers.

It turned out that:

• one such layer takes about seven to nine months to form

This allowed them to build a chronology of each turtle's life.

They found periods in the shells when growth slowed down.

These periods coincided with major changes in the ocean, such as:

• toxic algal blooms ("red tides")
• massive aggregations of sargassum

This means that the shell does indeed record stressful events in the marine environment.

Why it's important

Sea turtles spend most of their lives in the open ocean, where they are difficult to observe.

Now scientists can

• understand where the animals forage
• track changes in their diet
• detect the impact of environmental crises

The discovery provides a new tool for studying the ocean:

• tracks changes in ecosystems
• helps assess the impact of pollution and climate
• provides data to protect marine animals

Source

The study was conducted by scientists from the University of Miami together with an international team.

The results are published in the journal Marine Biology.