Science & Technology
Select a Level
NEW
17 Aug 2026
At roughly a meter long, Praearcturus gigas (illustrated) may have been the largest scorpion to ever exist. Franz Anthony
The Giant Sea Scorpion: A Prehistoric Ocean Monster
Warm-up → Read & Listen → Check Understanding → Language → Use It
WARM UP
Think Ahead: Which detail do you think appears in this story?
a) Sea scorpions lived millions of years ago in the water.
b) Sea scorpions flew in the sky like birds.
c) Sea scorpions were smaller than a tiny ant.
Ask:
(1) Do you like learning about ancient ocean animals?
(2) Would you be scared to see a giant creature in the water?
VOCABULARY
Scorpion
(noun)
Ocean
(noun)
Fossil
(noun)
Giant
(adjective)
Claw
(noun)
Ancient
(adjective)
Hunter
(noun)
An animal with pincers and a tail.
Example: The scorpion lived in the water millions of years ago.
A very large area of sea water.
Example: Big animals swam across the ocean.
The hard mark or bone of an old animal in a rock.
Example: Scientists found a fossil in the stone.
Very, very big in size.
Example: A giant creature swam in the deep river.
A sharp, curved part used by an animal to catch things.
Example: The sea scorpion used its big claw to grab fish.
From a very long time ago in history.
Example: We can study ancient animals from old rocks.
An animal that catches and eats other animals.
Example: The sea creature was a fast hunter in the sea.
Long ago, amazing animals lived in the deep water. Around 415 million years ago, a giant sea creature swam in the oceans. It was an ancient sea scorpion! Today, scorpions are small bugs that live on dry land. However, this ancient sea animal was bigger than a tall human. It grew up to two metres long.
Scientists found a large fossil in the rocks. A fossil is the hard mark of a very old animal. This sea scorpion had two big claws to catch fish. It used these claws to grab smaller animals in the river or sea. It was a fast hunter in the water.
This big sea scorpion did not walk on land. Instead, it used special flat legs like paddles to swim fast. Scientists are excited to learn more about this huge creature from the past!
Listen
Just the 16-centimeter pincer of Praearcturus gigas (pictured) is larger than most modern scorpions.
The Trustees of the Natural History Museum, London
DISCUSSION QUESTIONS
1. How big was the ancient sea scorpion?
2. How did the sea scorpion swim through the water?
3. What did the sea scorpion use its claws for?
4. Would you like to dig for animal fossils in rocks?
5. Why do you think scientists study ancient ocean animals?
FILL IN THE GAPS
FILL THE GAPS
Section 1: Fill in the Gaps
Word Bank: ancient, claws, fossil, giant
Long ago, amazing animals lived in the deep water. Around 415 million years ago, a _______(1) sea creature swam in the oceans. It was an _______(2) sea scorpion! Today, scorpions are small bugs that live on dry land. However, this ancient sea animal was bigger than a tall human. It grew up to two metres long.
Scientists found a large _______(3) in the rocks. A fossil is the hard mark of a very old animal. This sea scorpion had two big _______(4) to catch fish. It used these claws to grab smaller animals in the river or sea. It was a fast hunter in the water.
This big sea scorpion did not walk on land. Instead, it used special flat legs like paddles to swim fast. Scientists are excited to learn more about this huge creature from the past!
Section 2: Main Idea
What is the main idea of this story?
a) Ancient sea scorpions were giant ocean hunters that lived long ago.
b) Modern scorpions like to swim in deep river water.
c) Scientists found a small bird living inside an old rock.
UNDERSTANDING
Section 3: True or False
1. The ancient sea scorpion lived in the water around 415 million years ago. T/F
2. The giant sea scorpion was smaller than a tiny ant. T/F
3. The sea scorpion used flat legs like paddles to swim fast. T/F
Section 4: Put Events in Order
Put the following events in order from 1 to 3:
_____ The giant sea scorpion lived and hunted in ancient rivers and oceans.
_____ Over millions of years, the creature became a fossil in the rock.
_____ Scientists found the fossil and learned about the huge animal.
LANGUAGE
Section 5: Vocab Match
1. Ocean
2. Fossil
3. Giant
4. Claw
5. Ancient
a) Very, very big in size.
b) A sharp part used by an animal to grab things.
c) A very large area of sea water.
d) From a time very long ago.
e) The hard mark of an old animal kept in rock.
USE IT
Section 6: Discussion Builder
Choose the best word to complete each sentence:
1. The sea scorpion used its big _______ to grab fish.
a) claw
b) sky
c) plant
2. Scientists found an old _______ in a large rock.
a) fossil
b) tree
c) boat
Section 7: Sentence Unscramble
Put the parts in the correct order to make a sentence:
1. A) The giant B) swam C) sea scorpion D) in the E) ocean.
2. A) It used B) its big claws C) to catch D) small E) fish.
ANSWER KEY
Warm Up Answer:
a) Sea scorpions lived millions of years ago in the water.
Section 1: Fill in the Gaps
(1) giant
(2) ancient
(3) fossil
(4) claws
Section 2: Main Idea
a) Ancient sea scorpions were giant ocean hunters that lived long ago.
Section 3: True or False
True
False
True
Section 4: Put Events in Order
The giant sea scorpion lived and hunted in ancient rivers and oceans.
Over millions of years, the creature became a fossil in the rock.
Scientists found the fossil and learned about the huge animal.
Section 5: Vocab Match
1 - c
2 - e
3 - a
4 - b
5 - d
Section 6: Discussion Builder
a) claw
a) fossil
Section 7: Sentence Unscramble
A - C - B - D - E (The giant sea scorpion swam in the ocean.)
A - B - C - D - E (It used its big claws to catch small fish.)
Section 8: Discussion Questions
Student's own answers.
Thank you for your feedback!