An Ultimate Guide to Pterygotus: The Sea Scorpion

Leave a comment / / Updated on: 24th September 2023

Name Meaning“Winged One”HeightN/A
PronunciationTeh-ry-go-tusLength0.5 to 1.75 meters (1.6 to 5.7 ft.)
EraPaleozoic – Silurian to DevonianWeightN/A
ClassificationArachnomorpha, Eurypterida, PterygotioideaLocationAustralia, Europe, North America, South America

Pterygotus Sea Scorpion Pictures

Pterygotus | CoreyFord via iStock

The Pterygotus

Gage Beasley's Pterygotus Stuffed Plush Toy
Gage Beasley’s Pterygotus Stuffed Plush Toy

Pterygotus is an aquatic arthropod that lived from the Middle Silurian to the Late Devonian periods during the Paleozoic era.

These ancient sea creatures belonged to the Eurypterid order, also called sea scorpions due to the elongated tail some species had.

Pterygotus was one of the largest Eurypterids and were one of the most unique predators to roam the seas. 

First discovered in 1839, Pterygotus fossils have been found in several continents around the globe, suggesting they were not only common but widespread during their time.

Here you will learn about one of the largest arthropods to ever live, and the amazing things that have been discovered about the Pterygotus

Like many other extinct species known through fossils, there have been several mistakes made when studying Pterygotus, but with better studies and fossils, the enigma of this animal becomes more clear.

Gage Beasley's Prehistoric Shirt Collection
Gage Beasley’s Prehistoric Shirt Collection
Gage Beasley's Prehistoric Plush Collection
Gage Beasley’s Prehistoric Plush Collection

Physical Characteristics

Pterygotus was a carnivorous sea scorpion that lived in worldwide seas of the Silurian and Devonian Periods
Pterygotus was a carnivorous sea scorpion that lived in worldwide seas of the Silurian and Devonian Periods | CoreyFord via iStock

Pterygotus is one of the largest arthropods to ever exist, but there are several species of this animal that vary in their size.

These animals had two compound eyes on their side, with smaller ones on the top of their head.

The chelicerae of Pterygotus were long and robust, suggesting they were used to catch their prey.

The claws of these sea creatures were very similar to animals like crabs.

While Pterygotus had teeth on their claws, they lacked any scales or ornamentation that appeared on the rest of their body. 

Pterygotus had four pairs of small walking legs, with a fifth pair that were used to help them swim. 

Since their walking legs were very small they were not capable of walking onto land, and mainly resided in the water.

The body of Pterygotus was made up of segments that got larger toward their head, with their tail being shaped like a fan to help them swim.

With around 17 species, the size of the different Pterygotus species varied.

Gage Beasley Prehistoric's Pterygotus Size Comparison Chart
Gage Beasley Prehistoric’s Pterygotus Size Comparison Chart

The largest species is P. grandidentatus, which had a length of up to 1.75 meters (5.7 ft), while the smallest species only reached a length of around 50 cm (20 in.)

Pterygotus was not the largest of pterygotids, but there were several species that existed, growing more than 1 meter in length (3.3 ft.)

Habitat and Distribution

Pterygotus were fully aquatic and spent their life in marine environments around the globe, and it was impossible for them to go onto land.

When first discovered, Pterygotus were confined to England and North America, with many specimens found across the 20th century.

Fossils from Pterygotus have been found in the continents of Australia, Europe, North America, and South America, and the abundance of their fossils suggests their range was nearly cosmopolitan. 

Larger Pterygotus would have had to stay in deep waters, but the smaller species would have been able to live in more shallow waters. 

Remains from Pterygotus have primarily been found in Upper Silurian beds in Europe, but fossils from around the globe date these animals until the Late Devonian epoch.

Earth during the Silurian was different from the earth of today, and much of life, like Pterygotus lived in the seas. 

The oceans on earth in the Silurian were very widespread and began to grow due to the melting of glacier formations around the world. 

The sea levels on Earth rose greatly and continued into the Devonian period, and Earth’s life in the water diversified, changing the environment that Pterygotus lived in. 

Behavior and Diet

Illustration of a Pterygotus is a genus of giant predatory eurypterid, a group of extinct aquatic arthropods
Illustration of a Pterygotus is a genus of giant predatory eurypterid, a group of extinct aquatic arthropods | Nastasic via iStock

Since there have been no fossils of the gut of sea scorpions discovered, direct evidence of what these marine animals ate does not exist.

The eyes of Pterygotus were very large, and by looking at the interommatidial angle of their eyes, scientists believed these arthropods were predators.

The structure and body of Pterygotus suggest these animals were carnivores, and they also had compound eyes, which would help them track their prey.

The visual activity of Pterygotus was very high, and they had a large number of lenses in their eyes.

Pterygotus had enlarged claws that were curved, but each species’ claw length varied. 

Their claws were designed to puncture and grasp, and this was likely the main way they hunted.

To eat, the Pterygotus would have needed to chop up its prey and cut it into smaller pieces to fit it into their mouths.

Pterygotus 3D illustration
Pterygotus 3D illustration | Warpaintcobra via iStock

The mouth of Pterygotus and other eurypterids were not adapted for eating large portions and were smaller than modern-day crabs.

Like crabs, Pterygotus would have used their claws for ripping and tearing food, so it could be smaller to fit into their mouths.

Their claws would have been strong enough to hold onto animals while eating.

The walking appendages of Pterygotus were not used for eating or moving anything since they were so weak.

The diet of Pterygotus would have included fish, trilobites, and even other smaller eurypterids.

Life Cycle

Three Pterygotus swimming in the ocean
Three Pterygotus swimming in the ocean | CoreyFord via iStock

It is difficult to learn about the Pterygotus life cycle since there are not many defying traits of sexual dimorphism found in eurypterids.

Factors like size, body width, and the ornamentation of Pterygotus fossils and other related species are how scientists have attempted to figure out the sex of fossils found.

Paleontologists have managed to identify two types of appendages that would have been used for breeding by eurypterids, naming them type A and type B.

The genital appendage in Pterygotus is located in its eighth segment, and in fossils, it is represented by an elongated rod with an internal duct.

Gage Beasley Prehistoric's Pterygotus Concept
Gage Beasley Prehistoric’s Pterygotus Concept

While it is still not certain what appendage belonged to what sex, paleontologists believe that fossils with the type A appendages are females, while type b would represent males. 

The type A appendages are longer than type b, and it is believed it was like this since this was used for depositing eggs and storing sperm.

Type b sexual organs of sea scorpions are believed to belong to males, and this would have been used for producing and depositing sperm.

Scientists believe that the type b appendage belongs to male Pterygotus since it is much simpler than type A.

There is still a lot unclear about Pterygotus and how they reproduced, and in the future, what is accepted about these animals’ reproduction may change with new evidence. 

Evolution and History

Pterygotus head
Pterygotus head | CoreyFord via iStock

The first fossils of Pterygotus were found in Scotland, and western England, in beds, dating to the early Devonian period.

Their discovery was sent to Louis Agassiz, who described the fossils in 1839, naming them Pterygotus.

Pterygotus translates to “winged one”, and when first discovered, it was believed these remains belonged to a large fish, and this mistake was just one of many that would occur when describing these fossils.

The first species named in this genus was Pterygotus problematicus by Agassiz, but this species is no longer considered valid since it was based on a fossil with very few characteristics. 

The type species of Pterygotus was discovered in the Old Red Sandstone rocks in Scotland and was named P. anglicus in 1849.

P. anglicus is one of the most extensively known species of Pterygotus, but later findings like the species of P. cobbi found in New York in 1859 would expand this animal’s range.

The naming of several species of Pterygotus allowed for different subgenera and the Pterygotidae family to be created. 

Pterygotus fossils
Pterygotus fossils | Ghedoghedo via Wikipedia CC BY-SA 3.0

There have been more than 200 fossils of Pterygotus discovered, which have allowed for the extensive study of these animals.

Eurypterids first began to emerge in the Ordovician and continued to diversify until their populations began to peak in the Sulrian. 

Pterygotus and other eurypterids began to decline in the Devonian until going extinct.

It is believed that the competition from cephalopods and jawed fish is what contributed to the decline of eurypterids. 

The Late Devonian not only experienced the extinction of Pterygotus but also several other marine life.

It is still unclear what caused the death of a variety of sea animals during the end of the Devonian, but theories include global cooling, a decrease in sea level, or oceanic volcanoes. 

Interactions with Other Species

Digital illustration of the predatory scorpion, Pterygotus
Digital illustration of the predatory scorpion, Pterygotus | CoreyFord via iStock

Pterygotus spent their entire life in the ocean and were apex predators in the marine environments they lived in. 

In the beds where these animals were discovered other marine life also were present such as Leonaspis, Slimonia, Eusarcana, Parastylonurus, Mixopterus, Dolichopterus, Eurypterus, and Carcinosoma.

The animals that Pterygotus lived alongside depended on where they were located in the world and the time period. 

Pterygotus lived in both shallow and deep waters, depending on the species. 

In some regions, Pterygotus was the only eurypterid in their environment, while at other times, they lived alongside several other similar species. 

The claws of Pterygotus were not used for defense and were mainly used for eating. 

Pterygotus predators would have been larger sea life like fish or bigger eurypterids. 

Cultural Significance

Life restoration of Pterygotus
Life restoration of Pterygotus | Junnn11 via Wikipedia CC BY-SA 4.0

Pterygotus is an animal that represents life on earth from the Silurian to the Late Devonian periods when many of the animals lived in the water.

Life began to diversify during this period, and the fossils from Pterygotus helped better understand the environment of Earth more than 400 million years ago.

Today there are around 17 species of Pterygotus accepted, which include:

  • P. anglicus
  • P. arcuatus
  • P. barrandei
  • P. bolivianus
  • P. carmani
  • P. cobbi
  • P. denticulatus
  • P. floridanus
  • P. gaspesiensis
  • P. grandidentatus
  • P. impacatus
  • P. kopaninensis
  • P. lanarkensis
  • P. lightbodyi
  • P. ludensis
  • P. marylandicus
  • P. moroensis

In the past, there have been synonyms and species of Pterygotus that are no longer valid, but the mistakes overall have helped scientists gain a better understanding of these animals overall. 

There have been more than 200 fossils of Pterygotus discovered around the world, which have helped scientists better classify eurypterids and their relatives. 

Pterygotus model in the Czech National Museum, Prague
Pterygotus model in the Czech National Museum, Prague | Meridas  via Wikipedia CC BY-SA 4.0

Pterygotus has been essential in learning about life that lived more than 400 million years and how it changed over time. 


Pterygotus is one of the largest arthropods to ever exist, and there has been an abundance of their fossils discovered around the globe, which suggest these animals were very common in their era.

The body structure and appendages of Pterygotus suggest these marine animals were predators, and they had a similar feeding habitat to crabs, using their arms to rip food up to fit into their small mouths.

The waters that Pterygotus dominated began to diversify as the earth’s climate changed, and there are very few animals alive today that lived alongside this ancient species. 

Pterygotus are believed to have gone extinct in the Late Denovian period, and while they dominated the sea at this point in Earth’s history, life slowly began to take hold of the land. 

Since their discovery in the mid-1800s, it has taken extensive research to truly understand Pterygotus, and there are still many untold secrets waiting to be discovered about this ancient marine arthropod. 


What animals are Pterygotus related to? 

Pterygotus are most related to animals like the horseshoe crab today, which have a similar appearance.

The scorpions we see on land today are also related to the horseshoe crab, then they are related to sea scorpions.

Arthropods are one of the most diverse groups of animals in the world, and they can be found on the land and sea. 

How did Pterygotus swim?

Pterygotus was made up of several appendages, and near their rear had a tail shaped like an oar which was capable of moving up and down.

To swim, Pterygotus propelled itself through the water by flapping its body and tail, allowing them to move very quickly. 

Is Pterygotus the largest arthropod?

While Pterygotus is one of the largest arthropods to ever live, it is not the largest known to exist.

Jaekelopterus is the largest arthropod to exist, which is another type of eurypterid that reaches up to 2.3 to 2.6 meters (7.5 to 8.5 ft.) in length. 


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