Q 01/05

Despite the name, horseshoe crabs are not true crabs and are more closely related to which animals?

A) Lobsters

B) Spiders

C) Starfish

D) Sea snails

Answer · why

B) Spiders

Spiders, along with ticks and mites, are far closer kin than any lobster. Some genetic studies even place horseshoe crabs inside the arachnid family t...

Q 02/05

Which colour does a horseshoe crab's blood turn when it meets the oxygen in the air?

A) Green

B) Purple

C) Blue

D) Orange

Answer · why

C) Blue

Blue is the colour it turns in air, while inside the body the blood is closer to grey-white or pale yellow. The protein that carries its oxygen has no...

Q 03/05

What does a horseshoe crab mainly use its long, spiky tail for?

A) Flipping itself upright

B) Injecting venom into prey

C) Stinging its attackers

D) Spearing small fish

Answer · why

A) Flipping itself upright

Flipping itself upright is the tail's main job when a wave rolls the animal onto its back, and it doubles as a rudder. The tail cannot sting, but lift...

Q 04/05

What does horseshoe crab blood do on meeting bacterial toxins that makes it vital for testing drugs?

A) Glows in the dark

B) Turns bright pink

C) Bubbles and foams

D) Clots into a gel

Answer · why

D) Clots into a gel

Clots into a gel is the reaction, and even a tiny trace of toxin sets it off. Drug makers use an extract of the blood cells to check that vaccines and...

Q 05/05

Which body of water on the US Atlantic coast hosts the world's largest population of horseshoe crabs?

A) Chesapeake Bay

B) Cape Cod Bay

C) Delaware Bay

D) Long Island Sound

Answer · why

C) Delaware Bay

Delaware Bay draws hundreds of thousands of spawning crabs to its shores each May and June. The gathering is so dependable that scientists run a bay-w...