Speech 142, speech outline. The topic is Molinere Underwater Sculpture Park

Steps for Your Informative Speech

Informative Speech Outline
Presenter:
Student Name
General Purpose:
To inform
Specific Purpose:
To inform the audience about piranha
Central idea:
Piranha are a frequently incorrectly perceived fish with both fascinating
characteristics and a complicated history with humanity.
I. Introduction
A. “For the entrance to this cave is guarded by a creature so foul, so cruel, that no man
yet has fought with it… and lived! BONES of full fifty men lie *strewn* about its lair!
So! Brave knights! If you do doubt your courage or your strength, come no further,
for death awaits you all with nasty, big, pointy teeth…” (Forestater).
B. In this quote from Monty Python and the Holy Grail they may be talking about a
rabbit, but it might as well have been describing the fearsome fish, the piranha!
C. Through careful research of scientific studies and a journalist’s first hand encounters
with piranha I have learned many fascinating facts about piranha that I would like to
share with you.
D. I will give you an understanding of piranha by discussing
1. Their physical characteristics and behavior
2. The common perceptions about piranha
3. Their interactions with humans
II. Physical characteristics and behavior
A. General anatomy and the various types of piranha
1. Piranha are from the order of fish called Characiformes, also called Characins.
a. There are many different species of piranha.
i. Counts vary from as few as 18, to as many as 60.
b. Many of these species are completely harmless to human beings and are
actually herbivores.
c. The most well-known species and the most dangerous among them are
the red-bellied piranha, the red-eye piranha, and the piraya piranha
d. A close relative of the piranha, called a pacu, are often mistaken for
piranha and are reported as such in the news.
i. They are actually herbivores and pose no threat to humans.
2. Piranha vary in size
a. from the smallest at about 3 inches
b. up to the very largest at about 2 feet.
3. Their physical features allow them to effectively attack their prey
a. They tend to have large eyes and better hearing then most fish because
they possess a “linkage of bones called ossicles” (Grzimek, 335).
b. Their rather large lower jaw has even more disproportionately large
muscles controlling it.
c. Their teeth interlock perfectly, with a smaller set of upper teeth fitting
directly into their lower teeth.
B. Now moving on to piranha’s interactions with each other
1. Piranha travel in large groups called shoals, which is another word for schools
a. Evidence suggests that this behavior is largely done to avoid being
preyed upon themselves.
i. Piranha have many predators, including larger fish, river
dolphins, aquatic birds and the alligator like reptile called the
caiman.
ii. Anne Magurran, population biologist at the University of St.
Andrews and Helder Quieroz, Brazilian conservation biologist
performed a study in which they tested the anxiety level of
piranha in various shoal sizes.
iii. They tested the opercular rate, or breathing rate, of piranhas in
differently sized groups and discovered lower rates in larger
groups.
iv. They also exposed the piranha to a model of one of their
predators and noted less elevated breathing rates in the larger
shoals.
b. The shoal’s structure has the larger, older fish in the center, with the
smaller younger ones on the outside.
2. There have been relatively few investigations into piranha behavior, most
likely because the fish have been viewed as too difficult to handle.
B. Feeding habits
1. The red-bellied piranha tend to feed in shoals of 20-30 and they hide and wait
to ambush their prey.
2. The feeding frenzy occurs when the blood from injured prey enters the water,
spurring the entire shoal to attack (Grzimek, 339).
3. Most piranha attack fish without killing them, biting off pieces of the fish’s
tail, fins and scales.
a. This allows the damaged pieces to grow back, thus maintaining their
food supply.
4. Piranhas also scavenge for food, eating insects, plants and invertebrates.
5. They will devour the corpses of larger mammals and humans.
Transition: Now that you know some details about how they behave and their physical make up,
I would like to turn your attention to some common perceptions of piranha.
III. Common beliefs about Piranha
A. Unending appetite and tendency towards castration
1. Nature journalist Richard Conniff describes the common opinion of piranhas as
being that “Swarming, blood-maddened hordes of these little fish will strip to
the bone any creature dumb enough to wade into the South American lakes and
rivers where they live” (Conniff, 246-247).
a. This way of thinking in the United States in particular and worldwide
as well, can be largely traced back to Teddy Roosevelt’s reports on his
trips to Brazil, where he described piranha as “the most ferocious fish
in the world.”
b. News headlines about piranha attacks tend to keep this opinion of
piranha in the public consciousness.
i. An example of this is the Daily Mail headline “70 Christmas Day
Bathers Are Savaged,” which is about an incident where the
injuries were relatively minor (Conniff, 2014).
2. Another popular myth is that they tend to castrate people
a. This myth dates back to the sixteenth century and is due to the reports
of the Portuguese explorer Gabriel Soares de Sousa.
i. This information was based purely upon tales the locals told him
during his travels and not on observed experience.
B. Portrayal in popular culture
1. “In 1800 Alexander von Humbolt wrote an account of piranha shoals attacking
human victims. Since then their ferocity has been celebrated in horror movies
and piranhas are popularly believed to be dangerous pack-hunting animals,”
say Anne Magurran and Helder Quieroz in their study Partner Choice in
Piranha Shoals (290).
2. Piranha are shown to be primarily the property of villains in both Speed Racer
and the James Bond film You Only Live Twice.
a. The fact that the piranha are shown in both films to immediately attack
anything that enters their water implies that these fictional piranha were
most likely underfed.
3. In regards to the piranha in the 1978 film Piranha, most people ignore or are
ignorant of the fact that those piranha were actually genetically modified fish
and the screenwriter of the movie John Sayles said in an interview that “In
Piranha the horror is caused by the military” (Chute, 10).
4. Still this portrayal of piranha in film continues to this day, with the revival of
the Piranha franchise in 2010.
a. Even in that film the piranha are described as being prehistoric
creatures let loose by an earthquake, and not the actually piranhas
present in the world today.
Transition: So, this how people generally understand piranhas to behave, but how do they
actually behave around humans?
IV. Interactions with Humans
A. Most of human interactions with piranha involve human beings having control over
them.
1. They are kept as pets by some people.
b. This is illegal in some US states, including California, for fear of
people releasing the fish into the wild.
2. They are also found in aquariums and zoos.
a. The Los Angeles Zoo currently has a piranha exhibit.
3. There is also a huge market for piranha as food, particularly in South America,
so piranha fishing is a huge industry.
B. There is some danger in entering water where piranha swim, but it can be done safely
with caution.
1. There have been many reports of people swimming with piranha and not being
attacked.
2. Jan H. Mol of the University of Suriname says that he was never injured during
15 years of swimming with piranha, but he still says piranhas are dangerous in
certain situations (193).
a. These situations include when the water level is low and when there is
excessive splashing by the people in the water.
i. This is a partial explanation for why proportionally many more
piranha attacks happen to children than to adults.
C. Piranha attacks on humans do occur
1. Mol did a study on red-eye piranha attacks in Suriname along the Wayombo
River over the years and discovered that the increase in piranha attacks
corresponded with booms in population in the area, suggesting that the
disturbance of their natural surroundings by the increase in humans led to the
attacks.
2. Attacks on humans can also be caused by people swimming in water where
food or fish products has consistently been thrown or dropped into the water.
a. Piranhas view any flesh entering the water to be food and thus attack it.
b. This occurred at a recreation park in Suriname in 2001, where over 50
people were bitten by piranha over the course of a month. “Guests
were spilling food in the river that attracted small characiform fishes”
(Mol 193).
i. Still most attacks were limited to bites on the feet, with the most
serious injury being the loss of a toe.
3. Richard Conniff describes his experience of throwing chicken carcasses into
water where local fisherman on a river near the village of Boquerones in
Venezuela dump their fish guts to the effect that “the piranha hit the carcass the
instant it touched the water. After one minute and 20 seconds they’d eaten
everything except the spine and leg bones” (261).
a. At this same location, children had previously fallen into the river and
had to be hospitalized for several weeks, but they recovered with no
serious long term effects.
4. There are no substantiated reports of deaths caused directly by piranha attack.
a. Mol states that “many human deaths attributed to piranhas are probably
cases of scavenging on drowned persons” (193).
V. Conclusion
A. In conclusion, my goal today was to give you a better understanding of piranha.
B. I have done so by telling you about
1. Their physical characteristics and behavior
2. The common perceptions of them
3. Their interactions with humans
C. Now remember, if you’re attacked by piranhas, chances are that it will be “just a flesh
wound!” (Forstater).
References
Bould, M. (2009) The Cinema of John Sayles: lone star. London, United Kingdom: Wallflower
Characiformes. (2003). In Thoney, D.A., Loiselle, P.V. & Schlager, N. (Eds.) Grzimek’s Animal
Life Encyclopedia (2nd Edition, Vol. 4, pp 335-350). Farmington Hillis, MI: Gale Group
Chute, D. (1999). John Sayles: designated writer. In D. Carson (Ed.), John Sayles interviews (pp.
3-14) Jackson, MI: University Press of Mississippi. (Original work published 1981)
Conniff, R. (2009). Swimming with piranhas at feeding time: my life doing dumb stuff with
animals. New York, NY: W.W. Norton & Company, Inc.
Conniff, R. (2014, January 5). Shocking truth about piranhas revealed. The New York Times, pp. SR5.
Retrieved from http://www.nytimes.com/
Forstater, M. (Producer), & Gilliam, T. (Director). (1975). Monty Python and the Holy Grail [DVD].
United Kingdom: Michael White Productions
Magguran, A.E. & Queiroz, H.L. (2003). Partner choice in piranha shoals. Behaviour, 140(3),
289-299. doi: 10.1163/156853903321826639
Mol, J. H. (2006). Attacks on humans by the piranha Serrasalmus rhombeus in Suriname. Studies
On Neotropical Fauna & Environment, 41(3), 189-195.
doi:10.1080/01650520600630683
Piranha. (1969). In Burton, M. & Burton R. (Eds.), The International Wildlife Encyclopedia,
(Vol 13, pp 1777-1780). New York, NY: B.P.C. Publishing Limited
Queiroz, H., & Magurran, A. E. (2005). Safety in numbers? Shoaling behaviour of the
Amazonian red-bellied piranha. Biology Letters, 1(2), 155–157.
http://doi.org/10.1098/rsbl.2004.0267
Weitzman, S. H. & Vari, R. P. (1998). Characins & their allies. In J.P. Paxton (Ed.) & W.N.
Eschmeyer (Ed.), Encyclopedia of fishes. San Diego, CA: Academic Press