Presentation Outline: Crown of Thorns Starfish
By: Russell
Smith - Edited
by Ray Rector
I. Introduction
A. Opening
Satetement: The Crown of Thorns starfish has recently become a cancer-
like
agent of destruction to coral reef systems worldwide by consuming coral polyps
at an alarming rate.
Large groups of these starfish, called “outbreaks”, can consume
and destroy a reef very quickly.
B. Purpose of
Research and Presentation
1. Introduce audience to the
environemental crisis created by this reef
pest
2. Inform audience of the characteristics
and behavior of the Crown of Thorns
3. Inform audience of the negative causes
and effects surrounding outbreaks.
4. Inform audience of what is being done to
prevent present and future outbreaks
C. Preview
of Subtopics Covered
1. Anatomy/Biology
1. Habitat &
Locations
2. Life Cycle
3. Movement
4. Feeding
5. Defense Mechanisms and Enemies
6. Cause & Effect
7. History of Research
8. What can be done
II.
Body of Presentation
A. Anatomy
1.
Acanthaster Plansi
1. Generally 14-18 arms
1. Arms may shed and re-grow in 6 months
2. Tube feet
2. Average 25-35 cm in diameter
1. Up to 80 cm
3. Colors
1. Purplelish blue with red tipped spines
2. Brown and redish grey with red tipped spines
3. Greenish brown with yellow tipped spines
B. Habitat
1.
Prefer sheltered areas such as lagoons
2.
Avoids shallow water because of turbulence
3.
Deep water along reef front
C. Locations
1.
Tropics
2.
Indo-Pacific region
3.
Not found on reefs in the
D. Reproduction
1. Females shed eggs into water
a. Up to 60 million per season
2. Males spawn
3. Tend to gather together to spawn
4. High fertilization rate
5. Spawning
a. November to January
b. When
the water is warm
6. After fertilization the egg develops into larvae
7. Larvae feeds on phytoplankton
8. Metamorphosis into juvenile starfish
9. Feeds on encrusting algae for 6 months
10. Initial feeding
on coral at 1 cm size
11. Full grown
and reproductive in 2 years
E. Movement
1.
Does not use their arms directly
a. Tiny tube feet under the arms
b. Tube feet work using hydraulics
2. Unable to swim
3. Browses at .25 m/hr over live coral
4.
Travels 580 m in a week
4. Healthy starfish can move up to 1 km between reefs
F. Defense Mechanisms
1. Molecular sharp crystal tipped spikes
2. Spikes contain toxic compound called Saponin related
to steroids
3. Toxic to marine life and humans
4. Can cause nausea and vomiting
5. Can curl in a ball
G. Feeding
1. Night feeders
2. Predatory
3. Prefered food
a.
Staghorn coral
b.
Plate corals
4. Stinging effect of corals are ineffective
5. Able to shape around the coral
6. Eat the coral polyps out of their carbonate cups
7. Extrudes stomach through mouth over the coral
8. Releases enzymes
9. Digests the food
10. Single starfish can eat up to 13 square miles per
year
11. Can survive 6
months without food
H. Enemies
1. Great Triton
2. White Spotted Pufferfish
3. Titan Triggerfish
4. Yellow-faced Triggerfish
5. Harlequin Shrimp
6. Bristle or Fire Worm
7. Humans
I. Causes
1.
Human Factors
a.
Overfishing
b.
Collection of Triton
2.
Chemicals
a.
Stress the reef
b.
Do not affect the starfish
3.
Harm predators of the starfish
J. Effects
1.
Outbreaks consume entire reef systems
a. Primary Outbreaks
i.
Change in nutrients, temperature, salinity
b.
Secondary Outbreaks
i. Nearby outbreaks, Adult migration, Larvae Drift
ii. Larvae may drift up
to 400 km to infect new areas
c. Becoming
more frequent
2.
Destruction of the coral
a.
Ecosystem suffers
b.
Less Food
3.
No reef – Increased waves – shore erosion
K. What Can Be Done
1. Geographical surveys of outbreak-ridden areas
2. Tracking of movement
3. Starfish hunts
4. Save and replenish the Triton
5. Make interesting ornaments – sell at ocean gift
shops
6. Put more money and effort into research
III. Summary and Conclusion
A. Review of Subtopics Covered
1. Outlined the environmental threat to coral reefs caused by Crown of
Thorns.
2. Described the characteristics and behavior of the starfish pest.
3. Examined the cause and effect relationship of Crown of Thorn
outbreaks.
4. Offered several approaches to reduce and hopefully elliminate
outbreaks.
B. Concluding Thoughts:
1. Crown of Thorns Starfish are a great threat to the world’s reef ecosystems.
2. Over fishing of their enemies
disrupts the balance to control spread of starfish.
3. I
think it is important to continue research to see if there is a feasible way to
control the
population spread of the Starfish.
Bibliography
Walker, Pam. 2005.
The Continental Shelf. p. 80.
Walker, Pam. 2005.
The Coral Reef. P. 77.
Orme,
David and Bird, Helen. 2001.
The Blue Planet: Seas of
Moran,
http://www.aims.gov.au/pages/reflib/cot-starfish/pages/cot-000.html
The Crown of Thorns Strikes
Again. www.cruising-fiji.com/15COT.HTM
Out of
Control. http://www.this-magic-sea.com/ACANTH.HTM
Kosarek,
Nicole and Fabritius, Stephanie. Acanthaster Planci (crown-of-thorns
starfish). http://animaldiversity.ummz.umich.edu/site/accounts/information/Acanthaster_planci.html
Crown of
Thorns Starfish. http://library.thinkquest.org/10009/cots.htm
Harriot,
Vickie, Goggin,
http://www.reef.crc.org.au/publications/brochures/COTS_web_Nov2003.pdf