Grey Reef Shark: a two-minute wildlife lesson

Coral Reef · day 1 of 7

Five facts

1. The grey reef shark was the first shark seen warning others with a threat display: it hunches its back and drops its pectoral fins.
2. In the daytime, grey reef sharks often hang out in groups of 5 to 20 near steep reef edges. At nightfall they spread out to hunt.
3. Grey reef sharks hunt alone or in teams. Sometimes they trap schools of fish against the outside wall of a coral reef.
4. Grey reef sharks mostly stay in water less than 60 m deep, yet some have gone as deep as 1,000 m.
5. A grey reef shark has one to six pups every other year, after a gestation that can last 9 to 14 months.

The quiz

1. What posture does a grey reef shark take in a threat display?

• Upside down, still
• Tail up, nose down
• Hunched, with dropped pectoral fins (correct)
• Straight and stiff

The display is a hunched posture with dropped pectoral fins.

2. When do grey reef shark groups split up to hunt?

• In the evening (correct)
• At dawn
• At noon
• Never, they always hunt together

Their daytime groups break up in the evening when the hunting starts.

3. Against what do grey reef sharks pin schools of fish?

• The sandy seabed
• The outer walls of coral reefs (correct)
• The surface of the water
• A fishing net

They sometimes trap schools of fish against the outside wall of a coral reef.

4. How deep have grey reef sharks been known to go?

• 100 m
• 10 m
• 60 m
• 1,000 m (correct)

They mostly stay above 60 m but some have gone as deep as 1,000 m.

5. How long can a grey reef shark's gestation last?

• 9 to 14 days
• 2 to 3 months
• 9 to 14 months (correct)
• 20 to 24 months

Gestation can last 9 to 14 months.

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