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