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ChaetognathaChaetognatha
By: Brian Jones, By: Brian Jones, Owen Klassen, Owen Klassen, Sean StoquaSean Stoqua
IntroductionIntroduction Phylum Chaetognatha are often called Phylum Chaetognatha are often called
‘arrow worms’ ‘arrow worms’ Live in marine ecosystems Live in marine ecosystems Most are planktonic (80%) while some Most are planktonic (80%) while some
are benthic (20%) are benthic (20%) Most abundant type of animal present in Most abundant type of animal present in
many deep sea environmentsmany deep sea environments 120 modern species that range in size 120 modern species that range in size
from 2 to 120 mmfrom 2 to 120 mm One of the earliest BilateriansOne of the earliest Bilaterians
EvolutionEvolution
While early fossils have been found .. While early fossils have been found .. Their fossils do not preserve well …Their fossils do not preserve well …
Have been around since the Have been around since the Cambrian time periodCambrian time period
It has been hypothesized that they It has been hypothesized that they are linked to the deuterstome phyla are linked to the deuterstome phyla or acanthocephalan worms or acanthocephalan worms
CharacteristicsCharacteristics Transparent or translucent torpedo Transparent or translucent torpedo
shaped invertebrateshaped invertebrate Body is made up of three sectionsBody is made up of three sections There is a fin on the tail as well as two There is a fin on the tail as well as two
sets of lateral fins sets of lateral fins They have a circulatory system, gaseous They have a circulatory system, gaseous
exchange organs or excretory systemexchange organs or excretory system HermaphroditicHermaphroditic Gets its name from ‘grasping spines’ Gets its name from ‘grasping spines’
around its moutharound its mouth
Interesting FactsInteresting Facts
Some have bioluminescent organs in their Some have bioluminescent organs in their fins fins
Some feed on freshly hatched fish and Some feed on freshly hatched fish and other arrow worms other arrow worms
Contain neurotoxins used to paralyze and Contain neurotoxins used to paralyze and kill their preykill their prey
They were around during the same time They were around during the same time period of the dinosaursperiod of the dinosaurs
Today they can be found in every ocean in Today they can be found in every ocean in the worldthe world
More FactsMore Facts
They are all carnivoresThey are all carnivores Although they have been around for 300 Although they have been around for 300
million years, they are still abundant in million years, they are still abundant in numbersnumbers
Considered a useful model for Considered a useful model for examining ancestral bilateran examining ancestral bilateran
Their nervous system is relatively simple Their nervous system is relatively simple and resembles that of a protosome and resembles that of a protosome
Also known as “glassworms” Also known as “glassworms”
VideoVideo
https://www.youtube.com/watch?https://www.youtube.com/watch?v=PkGhxtpK7IUv=PkGhxtpK7IU
The first 40 seconds of this video The first 40 seconds of this video demonstrates the movements of the demonstrates the movements of the cool grasping spines of the cool grasping spines of the chaetognatha chaetognatha
SourcesSources
http://academic.evergreen.edu/t/thuesehttp://academic.evergreen.edu/t/thuesene/chaetognaths/chaetognaths.htmne/chaetognaths/chaetognaths.htm
http://www.helium.com/items/1291972-http://www.helium.com/items/1291972-what-are-arrow-wormswhat-are-arrow-worms
http://eol.org/pages/1740/overviewhttp://eol.org/pages/1740/overview http://www.princeton.edu/~achaney/http://www.princeton.edu/~achaney/
tmve/wiki100k/docs/Chaetognatha.htmltmve/wiki100k/docs/Chaetognatha.html http://eprints.lib.hokudai.ac.jp/dspace/http://eprints.lib.hokudai.ac.jp/dspace/
bitstream/bitstream/2115/21862/1/23%282%29_P95-183.pdf2115/21862/1/23%282%29_P95-183.pdf