Chaetognaths, also known as arrow worms, are small marine animals found throughout the world's oceans. They have a slender transparent body with fins and a tail that aid in locomotion. Arrow worms feed voraciously on plankton and small fish using spines around their mouth. Reproduction is hermaphroditic, with internal fertilization producing planktonic eggs. Locomotion involves bursts of undulating body movements propelled by tail fins and stabilized by side fins.

1. Phylum
Chaetognaths
Submitted by: Mohit Raj
M.Sc Zoology (1 Sem)

2. Contents
➢ Classification
➢ Habitat
➢ General Description
➢ Mode of nutrition
➢ Reproduction
➢ Locomotion

3. Classification
Kingdom : Animalia
Phylum : Chaetognatha
Class : Sagittoidea
Order : Aphragmophora
Phragmophora

4. Chaetognatha
The name Chaetognatha comes from the greek word ( Chaite
- means Long flowing Hair and Gnathos - Meaning Jaw.

5. Habitat
● They found on all marine waters, from surface
tropical waters and shallow tide pools to the deep
sea and polar regions, most species are planktonic,
but a small number of species are bentic.
● About 20% live just above the ocean floor and can
attach to seaweed or rocks.

6. General Description
● Chaetognatha commonly known as Arrow Worms.
● There are more than 120 modern species assigned
to over 20 genera.
● They are coelomates animals.
● Small in size with straight, slender, transparent
body displaying perfect bilateral symmetry.
● They are usually colourless, slightly opaque.

7. ● The body is divided in the parts by
internal partitioning: Head, Trunk and
Tail.
● Has a no circulatory system or gaseous
exchange organs.
● Possesses no excretory system.
● Chaetognaths classed as deuterostomes
by embryologists Lynn Margulis and K.
V. Schwartz in Five Kingdom
classification.
● Thomas Cavalier-Smith places them in the
protostomes in his Six Kingdom
classification.

8. Mode of Nutrition
● Chaetognaths are carnivorous predators.
● These voracious meat-eaters catch large
numbers of copepods, larval fish,
crustaceans, swallowing them whole.
● The large spines around their mouth helps
them grab and restrain their prey and
immobilize with neurotoxins.
● Due to absence of excretory system Waste
materials are simply excreted through the skin
and anus.

9. Reproduction
● Reproduction normally sexual and hermaphroditic. Meaning they all
possess both male and female sex organs.
● The Female organs ( the ovaries) are just behind the trunk.
● The male organs ( the testis) are in the tail.

10. ● Fertilization is internal.
● The eggs are planktonic, develop in
marsupial sacs or attached to algae, and
hatch into miniature versions of the
adult, without a well-defined larval
stage

11. Locomotion
● Chaetognaths swim in short bursts using a
dorso-ventral undulating body motion,
where their tail fin assists with propulsion
and the body fins with stabilization and
steering.
● Their torpedo-like body shape allows them
to move quickly through the water.
● Chaetognatha alternate between swimming
and floating.

12. ● The fins along their body are not
used to swim, but rather to help
them float.
● They usually swim to the surface
at night and descend during
daytime.

13. Reference
● www.Animaldiversity.org/accounts/chaetognatha
● www.earthlife.net/inverts/chaetognatha.html
● www.newworldencyclopedia.org/entry/chaetognatha
● https://en.wikipedia.orh/wiki/chaetognatha
● eol.org/pages/1740/overview
● www.polarlife.ca/organisms/invertibrates/marine/invertibrates/chaetog
natha.html

14. THANK YOU