Question 1

True or false: Horseshoe crabs are venomous and can deliver a painful sting with their tail spine.

Accepted Answer

False. Their tail (telson) is harmless—used for flipping over, not stinging. They lack venom glands.

Question 2

True or false: Their blue blood is used to detect bacterial contamination in medical vaccines and devices.

Accepted Answer

True. The blood contains amebocytes that clot around endotoxins, making it vital for sterility testing.

Question 3

True or false: Horseshoe crabs are found only in the waters off the Atlantic coast of North America.

Accepted Answer

False. Four species exist; one lives along the Atlantic coast, but others inhabit Asia, including Japan and Indonesia.

Question 4

True or false: They can survive out of water for up to a week by breathing through their book gills.

Accepted Answer

True. Their book gills retain moisture, allowing them to stay alive on beaches during spawning.

Question 5

True or false: Female horseshoe crabs are smaller than males and lay eggs only once in their lifetime.

Accepted Answer

False. Females are larger than males and return to spawn multiple times each breeding season.

Question 6

True or false: Horseshoe crabs are more closely related to spiders and scorpions than to true crabs.

Accepted Answer

True. They are chelicerates, belonging to the same subphylum as arachnids, not crustaceans like true crabs.

Question 7

True or false: Horseshoe crabs have ten eyes, including light-sensitive cells on their tail.

Accepted Answer

True. They have two compound eyes, three simple eyes, and five additional light receptors, including on the telson.

Question 8

True or false: These animals are considered living fossils because they haven't evolved in over 200 million years.

Accepted Answer

False. While ancient, they have evolved gradually; molecular studies show genetic changes over time.

Horseshoe Crab Trivia Questions