The Horseshoe Crab – a “Living Fossil”

Posted by on Jan 11, 2013 in Johnsons from the Front | 0 comments


Recently while walking along a Florida beach on the Gulf of Mexico, I found the remains of several horseshoe crabs. I was quite excited, because just a week before I had been able to observe live horseshoe crabs at the Florida Aquarium in Tampa. Here on the beach I had an opportunity to actually hold and study them.

The outer body of the horseshoe crab consists of a hard shell in three sections. The front section protects the soft parts on the underside – the eyes (2 primary compound eyes, and 7 secondary “simple eyes”, 2 of which are on the underside), legs (5 pair used for walking, swimming or moving food into the mouth), pincers, mouth, brain, and heart. The middle section is hinged to the front section and protects the gills and reproductive organs. The third section is the long, straight, rigid tail it uses to flip itself over when turned upside down.

Horseshoe Crab Trivia:

  • It is not a “true crab” (it’s not a crustacean), but an arthropod and is classified with scorpions, spiders, and extinct trilobites.
  • Although they scurry around on the shallow ocean floor, they swim upside down, inclined at about 30° to the horizontal.
  • They find their food (worms, mollusks, crustaceans and small fish) on the soft and sandy or muddy bottom.
  • Rather than hemoglobin in their blood, they have hemocyanin, which contains copper, making their blood blue in color.
  • Their blood contains a protein used to screen drugs and vaccines for contaminants.


Evolutionary scientists call the horseshoe crab a “living fossil” because fossils of the horseshoe crab (supposedly 450 million years old) have been found that are identical to the living horseshoe crab we find today. Hmmm?  Supposedly millions upon millions of years of mutations and natural selection and yet there is no evidence for evolutionary change in this critter.

The horseshoe crab is not a unique “living fossil”. We also find hundreds of other animals and plants that have stayed the same over supposed millions of years. A few examples are sharks, crinoids, Wollemi pine trees, ginkgo trees, tuataras, crocodiles, alligators, coelocanth fish, squids, shrimp, chambered nautiloids, brachiopods, clams and dragonflies.

The evidence of “living fossils” shows very little to no change in these living creatures. “Living fossils” make no sense for the evolutionary model or the long ages required for evolution.


Lanny Johnson

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