Atlantic horseshoe crab

Atlantic horseshoe crab Introduction

Atlantic horseshoe crabs may appear alien, but their history as earthlings is pretty impressive. They’ve been around for 450 million years, predating the dinosaurs by more than 200 million years. They live on the Atlantic coast of North America, from Maine to down and around the Florida coast to Alabama and Mississippi. They also live around the northern Yucatán Peninsula in Mexico. Despite their common name, horseshoe crabs are more closely related to spiders and scorpions than to “true crabs,” which are crustaceans. They’re in the class Merostomata, which means “legs attached to the mouth” because their mouths are literally in the center of all 10 legs. Horseshoe crabs also have 10 eyes—a pair of compound eyes on the front shell and more photo receptors along their tail. Horseshoe crabs’ bodies are divided into three segments. The head, or prosoma, houses most vital organs, including the heart and the brain. The middle segment, the opisthosoma, contains the back gills and ridges that help with movement. The third segment is the tail, or telson, which looks like a big stinger but is used to help these animals flip if overturned and acts as a rudder as they move across the ocean floor. Horseshoe crabs molt their distinctive shells about 17 times before reaching maturity at age 10.

Keywords to learn

Receptors: An organ or cell able to respond to light, heat, or other external stimulus and transmit a signal to a sensory nerve

About Me

Hey Kids, my name is Asher the Atlantic horseshoe crab and I am very happy to meet you. Learn more about me and my species @



Key Data

  • Order:
  • Lifespan:
    20 to 40 years.
  • Class:
    Euchelicerata .
  • Scientific Name:
    Limulus polyphemus.
  • Mass:
    Up to 10 pounds.
  • Length:
    Two feet long; one foot wide.
  • Region found:
    Gulf of Mexico and along the Atlantic coast of North America.
  • Population Status:
    Near Threatened .
  • Current population trend:
  • Diet:
  • Sexual maturity:
    9-12 years.


Atlantic horseshoe crabs may appear alien, but their history as earthlings is pretty impressive. They’ve been around for 450 million years, predating the dinosaurs by more than 200 million years. 


Now that you know more about the Atlantic horseshoe crab by learning the key data above, be sure also to check out the fun facts. When you are finished learning the facts, try answering the questions in the Q&A corner on the bottom right side of the page.



Download questions about the Atlantic horseshoe crab here: Atlantic Horseshoe Crab (answers are on this page)


Teachers. For more in depth work sheets on the crab. Click on Kidskonnect Worksheets



Atlantic horseshoe crab Facts for Kids

  • # 1. Most of us probably owe our lives to horseshoe crabs. Their blue, copper-based blood contains lysate, which reacts to bacterial toxins by clotting. Horseshoe crab blood has long been harvested to test everything from water to intravenous drugs for contamination.
  • # 2. Horsehoe crap key to making vaccines for diseases such as COVID-19. Crabs are returned to the wild afterward but the process may have a negative effect on spawning. 
  • # 3. A synthetic version of the crabs blood has been produced that appears to be on course to eliminate the need to use animals in endotoxin detection.
  • # 4. The pharmaceutical industry is beginning to accept this substitute but it has not yet ended the practice of harvesting these crabs for their blood.
  • # 5. Spawning season comes at different times of year, depending. ing on location, but the largest lovefest happens at Delaware Bay, where thousands of horseshoe crabs crawl onto the beaches in May and June. 

Q&A Corner

# 1. What region does the Atlantic horseshoe crab live in?


# 2. What is the average lifespan of the Atlantic horseshoe crab?


# 3. When is Atlantic horseshoe crab spawning season?


# 4. What is the Atlantic horseshoe crab blood used for?


# 5. How many legs does the Atlantic horseshoe crab have?


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