Chaetognatha
By: Brian Jones, Owen
Klassen, Sean Stoqua
Introduction
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Phylum Chaetognatha are often called ‘arrow
worms’
Live in marine ecosystems
Most are planktonic (80%) while some are
benthic (20%)
Most abundant type of animal present in many
deep sea environments
120 modern species that range in size from 2 to
120 mm
One of the earliest Bilaterians
Evolution
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While early fossils have been found .. Their
fossils do not preserve well …
Have been around since the Cambrian time
period
It has been hypothesized that they are linked to
the deuterstome phyla or acanthocephalan
worms
Characteristics
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Transparent or translucent torpedo shaped
invertebrate
Body is made up of three sections
There is a fin on the tail as well as two sets of
lateral fins
They have a circulatory system, gaseous
exchange organs or excretory system
Hermaphroditic
Gets its name from ‘grasping spines’ around its
mouth
Interesting Facts
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Some have bioluminescent organs in their fins
Some feed on freshly hatched fish and other
arrow worms
Contain neurotoxins used to paralyze and kill
their prey
They were around during the same time period
of the dinosaurs
Today they can be found in every ocean in the
world
More Facts
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They are all carnivores
Although they have been around for 300 million
years, they are still abundant in numbers
Considered a useful model for examining
ancestral bilateran
Their nervous system is relatively simple and
resembles that of a protosome
Also known as “glassworms”
Video
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https://www.youtube.com/watch?v=PkGhxtpK
7IU
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The first 40 seconds of this video demonstrates
the movements of the cool grasping spines of
the chaetognatha
Sources
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http://academic.evergreen.edu/t/thuesene/chae
tognaths/chaetognaths.htm
http://www.helium.com/items/1291972-whatare-arrow-worms
http://eol.org/pages/1740/overview
http://www.princeton.edu/~achaney/tmve/wik
i100k/docs/Chaetognatha.html
http://eprints.lib.hokudai.ac.jp/dspace/bitstrea
m/2115/21862/1/23%282%29_P95-183.pdf