Arrow worm facts for kids
Quick facts for kids Arrow wormsTemporal range: Lower Cambrian to Recent
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| Spadella cephaloptera | |
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Protostomia (disputed)
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| Phylum: |
Chaetognatha
Leuckart 1854
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Arrow worms, also known as Chaetognatha (say "kee-TOG-nath-ah"), are a group of small ocean animals. They are mostly predators, meaning they hunt other tiny creatures. You can find huge numbers of them floating in the ocean worldwide as part of the plankton.
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Arrow Worms: Tiny Ocean Hunters
Arrow worms are amazing creatures, even though they are very small. They are an important part of the ocean's food web.
What Are Arrow Worms?
Most arrow worms are clear, like glass, and shaped like a torpedo. This helps them hide in the water. Some types that live in the deep sea can be orange. They can be as tiny as 2 millimeters (about the size of a pinhead) or grow up to 120 millimeters (about 4.7 inches) long.
Scientists have found about 120 different kinds, or species, of modern arrow worms. These species are grouped into 20 different genera (which is the plural of genus).
Where Do They Live?
You can find arrow worms in almost every part of the ocean.
- They live in warm tropical waters near the surface.
- They can be found in shallow tide pools along the coast.
- They also live in the very deep parts of the ocean.
- Even in the freezing polar regions, you can find them.
About 20% of arrow worm species are benthic. This means they live on the ocean floor and can attach themselves to algae or rocks.
How Do They Hunt?
Arrow worms are skilled hunters. They use special grasping spines around their mouths to catch their prey. Some species even use a powerful poison called tetrodotoxin to stun the small animals they want to eat. This poison helps them quickly catch their food.
Ancient History of Arrow Worms
Arrow worms have been around for a very long time! Scientists believe they first appeared during the Cambrian Period. This was a time over 500 million years ago when many new types of life first appeared on Earth.
Complete fossils of arrow worms have been found in places like China and the famous Burgess Shale in British Columbia, Canada. These fossils help scientists learn about how these ancient animals looked and lived.
Scientists usually group arrow worms with animals called protostomes. This is a big group of animals that includes insects, snails, and worms.
Images for kids
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The jaw organ of an arrow worm from the genus Sagitta
See also
In Spanish: Chaetognatha para niños
