Megarachne servinei

Species
Megarachne servinei

Size
Length up to 16 in.

Prey
Tiny invertebrates

Where?
Fossils have been found in Argentina, in South America

When?
About 300 million years ago during the Carboniferous Period

Sound off
meg-a-RAK-nee

Did You Know?
Megarachne used to be listed in Guinness World Records as the largest spider in the world.

In 1980 a scientist discovered a fossil of what he thugh was the biggest spider to ever live. As large as a small dog, Megarachne had a heavily armored body, giant eyes and a leg span of up to 20 inches! For many years, the life of this huge swamp-dwelling creature was a mystery. Only now do we know the true story-Megarachne was a actually a giant prehistoric sea scorpion."What Big Eyes You Have! Megarachne's large compound eyes measured up to half an inch in diameter. When the creature was underwater its eyes probably poked up from the water like a crocodile's.""In Good Company: Like modern spiders and scorpions, Megarachne had a pair of feeding appendages at the front of its mouth called Chelicerae, which it used to pass food into its mouth."

Spider or Scorpion?
The first Megarachne fossil was locked away soon after its discovery. Since no one could examine the specimen, they couldn't prove that it really was a prehistoric spider. Finally, in 2004, a British spider expert was allowed to study the fossil, and he quickly found that Megarachne actually belonged to the family of prehistoric sea scorpions known as eurypterids. Unlike spiders, which have eight small eyes, Megarachne had two big ones. And it had a hard shell with ridges across its back-unlike any spider known to science.

To date, only two Megarachne fossils have been discovered."Clean Sweep: Though most eurypterids were predators, scientists believe Megarachne was a 'sweep feeder.' Its feeding appendages had long combs on them, like baleen plates in a whale's mouth, which Megarachne used to sift through mud and water and filter out food.""Time to Change: Megarachne most likely lived on land and in the water, like a crab. It probably molted, or shed, its outer shell in water-its bare legs would have been too soft to support its weight until its new exoskeleton hardened."Since Megarachne has been reclassified, the title of largest spider in history now belongs to the goliath bird-eating spider. This hairy monster from South America has a leg span of up to one foot!