European Green Crab: a two-minute wildlife lesson

At the Seaside · day 6 of 7

Five facts

1. A female green crab can produce more than 400,000 eggs. Her larvae grow up offshore, then settle on the shore as tiny crabs.
2. Green crabs survive from 0 °C to 30 °C, so they can even live under the ice in winter.
3. A green crab can crush up to 40 small clams, 13 mm long, in a single day.
4. First recorded in San Francisco Bay in 1989, it reached British Columbia in 1999, extending its range by about 750 km in ten years.
5. In 2025 scientists finished sequencing the entire European green crab genome, creating a detailed genetic map.

The quiz

1. How many eggs can a single female green crab produce?

• About 400
• More than 4,000
• More than 400,000 (correct)
• Only a few dozen

A single female can produce more than 400,000 eggs.

2. What temperature range can green crabs survive?

• 0 °C to 30 °C (correct)
• 10 °C to 15 °C
• 20 °C to 50 °C
• -10 °C to 10 °C

They can survive from 0 °C to 30 °C.

3. How many clams can a green crab crush per day?

• Up to 4
• Up to 400
• Up to 4,000
• Up to 40 (correct)

It can crush up to 40 clams per day.

4. In which year was the green crab first recorded in San Francisco Bay?

• 1959
• 1989 (correct)
• 1999
• 2009

It was first recorded there in 1989.

5. What did scientists finish sequencing in 2025?

• The entire green crab genome (correct)
• A green crab's shell
• A clam's genome
• The ocean's salt levels

They completed the sequencing of the entire genome.

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