What happens on Delaware Bay beaches each spring?

Sea turtles hatch by the million

Why is their blood valuable?

It helps test medicines for bacteria

Delaware Bay Quiz: Horseshoe Crabs and Red Knot Migration

This Delaware Bay quiz watches the beaches where ancient horseshoe crabs spawn and hungry shorebirds refuel. Play 10 interactive questions on spawning tides in May and June, why horseshoe crabs are not true crabs, their blue blood, red knots flying from South America to the Arctic, the 2014 threatened listing, Cape May and Cape Henlopen.

Start Delaware Bay Quiz

🎯 Daily Trivia Challenge • 🧠 10 Questions • ⏱️ 150 Seconds

Question 1 / 10 Time: 150s

Event
What happens on Delaware Bay beaches each spring?
Season
When does spawning peak?
Relative
Which animals are horseshoe crabs more closely related to?
Blood
What color is horseshoe crab blood?
Medicine
Why is their blood valuable?
Bird
Which shorebird depends on the crab eggs?
Route
Where do red knots fly after Delaware Bay?
Status
When was the red knot listed as threatened in the US?
Capes
Which two capes guard the bay's mouth?
Age
How old is the horseshoe crab lineage?

Explanations: answer key for all 10 questions

Q1: What happens on Delaware Bay beaches each spring?
Answer: Horseshoe crabs spawn
It is the largest spawning in the world.
Q2: When does spawning peak?
Answer: Late May and June
High tides around full and new moons matter.
Q3: Which animals are horseshoe crabs more closely related to?
Answer: Spiders and scorpions
They are not true crabs.
Q4: What color is horseshoe crab blood?
Answer: Blue
Copper carries its oxygen.
Q5: Why is their blood valuable?
Answer: It helps test medicines for bacteria
A test called LAL relies on it.
Q6: Which shorebird depends on the crab eggs?
Answer: Red knot
It refuels during migration.
Q7: Where do red knots fly after Delaware Bay?
Answer: To the Arctic to breed
Some start at Tierra del Fuego.
Q8: When was the red knot listed as threatened in the US?
Answer: 2014
Fewer eggs meant fewer birds.
Q9: Which two capes guard the bay's mouth?
Answer: Cape May and Cape Henlopen
They lie in New Jersey and Delaware.
Q10: How old is the horseshoe crab lineage?
Answer: Hundreds of millions of years
They are often called living fossils.

Horseshoe Crabs and the Red Knot Stopover

Every spring, Delaware Bay hosts the largest horseshoe crab spawning in the world. On high tides in late May and June, especially around full and new moons, crabs crowd the beaches of Delaware and New Jersey to lay billions of tiny green eggs in the sand.

Horseshoe crabs are not true crabs; they are closer to spiders and scorpions and belong to a lineage hundreds of millions of years old. Their blue, copper-based blood is used in the LAL test, which checks medicines and vaccines for bacterial contamination.

Red knots, shorebirds that may fly from Tierra del Fuego to the Arctic, stop here to feast on crab eggs and nearly double their weight. As crab numbers fell, the red knot was listed as threatened in 2014. Birders gather from Cape May to Cape Henlopen to watch this spectacle.

What This Quiz Teaches

Nature fans will enjoy these questions.

When spawning happens
What horseshoe crabs really are
Why their blood matters
Which birds rely on them
How they are protected

Did You Know?

Volunteers flip stranded crabs back onto their legs.
Horseshoe crabs have ten eyes.
Their tail, the telson, helps them steer and flip over.
Laughing gulls also eat the eggs.
Harvest limits now protect the crabs in the bay.