By: Hannah
What do you think of when you hear
the word piranha? According to Sue Anne Zollinger in “Piranhas – Ferocious
Fighter or Scavenging Softie?” most people think of the horror films version of
piranha, fish with large, sharp teeth tearing a person apart after they fall
into the water. Red-Bellied Piranhas are more than what is seen in a horror
movie.
According to Wikipedia, Seriously Fish,
and WAZA (World Association of Zoos and Aquariums), the scientific
classification for Red-Bellied Piranha is that they belong to the Family:
Animalia, Phylum: Chordata, Class: Actinopterygii, Order: Characiformes,
Family: Serrasalnidae, Genus: Pygocentrus (pygocentrus meaning ‘tail’ and
kentron meaning ‘sharp point’), Species: P. nattereri (nattereri for an
Australian naturalist from the 1800’s). They belong to the same family as pacu
and tetras. They are fresh water fish that are omnivorous, scavengers.
Red Bellied Piranha gets their name
because their bellies are red. They also have broad, serrated, triangular,
razor sharp teeth that make slicing chunks of fish free. Animal World said that
red bellied piranha can reach up to 13 inches in the wild, but are smaller in
an aquarium. The website Bristol Zoo said that red bellied piranhas can weigh
up to a maximum of 3.5 kg. Baby red bellied piranhas have silver bodies with
dark blotches. Red bellied piranhas get blackish spots behind the gills and the
anal fin is usually black at the base, while the pectoral and pelvic fins vary
from red to orange. It was also noted that males have a darker red belly than
females.
According to Seriously Fish,
Wikipedia and Animal World, red-bellied piranhas live in tropical freshwater
areas. These fish have a wide distribution throughout the Amazon and Orinco
Basin Rivers in South America. Red-bellied Piranhas are found to be an abundant
component of the fish in the Mamiraua Sustainable Development Reserve on the
flooded forest of the Amazon River according to Magurran and Queiroz. They have
also been found in the waters of major rivers, like Rio Paraguay. They have
also been found in white water streams of South America. The water in these
areas is about 15 to 35 degrees Celsius.
Although red-bellied piranha have
been portrayed, in horror movies, as being blood thirsty killers who eat large
animals and humans who stray into the water, they are actually omnivores and
scavengers. Large piranha hunts for food in the dawn, late afternoon and early
evening. Younger, smaller piranha hunts for food during the day and hide from
the larger piranha that would eat them. According to Animal World, red-bellied piranhas are not
picky eaters. Red-bellied piranhas tend to eat fish, molluscs, insects,
crustaceans, snails, algae and other water plants. According to Seriously Fish,
they will attack sick or dying fish, feed on fins from larger fish and scavenge
carcasses. They will hide and chase some fish from vegetation in shallow
waters. It is during the dry season, when food is scarce that shoals of piranha
are known to attack and have feeding frenzies. It is rare, according to
Magurran and Queiroz, for piranhas to attack large, healthy prey.
According to Edda Kastenhuber and
Stephan C. F. Neuhass, red-bellied piranhas can produce a wide variety of
acoustic sounds. Red-bellied piranhas can use phonetic language such as “hums,
growls, grunts, boat whistles, hoots chirps and many other sounds.” The
red-bellied piranhas have two basic mechanisms to help generate sound. They use
muscle contractions, a displacement in the swim bladder and a clicking of bony
parts like teeth and fins. Sound making fish vocalize in a seductive manner
during courtship and mating season. They make sounds to aggressively defend
their territory and also for alerting to danger in their shoals. But it was
noted that most of the vocalizations were heard only when the piranhas were
captured in a hand or a net.
According to Wikipedia, Margurran
and Queiroz, some of the breeding habitats of the red-bellied piranha are
unknown to researchers. Researchers say that red-bellied piranha behavior in
nature has revealed certain behavioral patterns around their nesting sites.
Adult piranhas will swim side by side in a small circle, sometimes swimming
opposite directions. One female piranha can lay up to 5,000 eggs, which the
male and female piranhas defend until the eggs hatch. Up to 90% of the eggs
survive.
Red-bellied piranhas form into
shoals where the bigger piranhas are in the middle and the smaller piranhas are
on the outside. According to Webster Dictionary, shoals are a pack of piranha
all grouped together. According to Magurran and Gueiroz, red-bellied piranhas
find their mates in their shoals. Their decision on who is in the shoal is
based on the size of the piranhas. They also choose their mates depending on
the sizes. When the water is high in the rivers, a shoal can reach up to 30
individual piranhas. Large red-bellied piranha showed a strong preference for
large shoaling partners, while the smaller piranhas did not have a preference
in the sizes of their partners.
Red-bellied piranhas are known for
their reputation for being ferocious carnivores. According to Seriously Fish, Wikipedia, and
WAZA, the red-bellied piranha reputation is only a Hollywood movie myth.
Red-bellied piranhas only attack people when it is the dry season or they are
provoked. According to Seriously Fish, the myth began when American President,
Theodore Roosevelt made a visit to the Amazon in Brazil in 1913 and he
witnessed an attack. Then a movie was made called “Piranha,” by Joe Dante,
which has been compared to “Jaws.” These films and stories of large Piranha
shoals attacking humans, just fuel the exaggerated and erroneous reputation of
piranhas.
During my research, I read a few
articles where red-bellied piranhas were dumped into other fresh waters and
then attacked humans. But these waters would become too cold for the piranhas
to survive and were more than likely dumped from someone’s aquarium. It is
because of these rare attacks and the fact that only a very well trained person
should handle them, that the piranhas myth continues today.
Works Cited:
Arkive.org –
Red Bellied Piranha
Magurran,
Anne E; Helder L. Queiroz; University of St. Andrews, Scotland, “Partner Choice
in Piranha Shoals”
The Nature
Conservancy
Putz,
Brian, University of Michigan-Ann Arbor, “Pygecentrus Nattereri Red Bellied
Piranha,” 10/17/2012
Queiroz,
Helder Lima; Marcela B. Sobanski; Anne E. Magurran; “Reproductive strategies of
Red-Bellied Piranha (Pygocentrus nattereri Kner, 1858) in the white waters of
the Mamiraua flooded forest, central Brazilian Amazon”
Seriously
Fish.com – Red Bellied Piranha
University of
Zurich, Institute of Molecular Life Sciences; Neuroscience Center Zurich and
Center for Integrative Human Physiology, Winterthurerstrasse 190, CH-8057
Zurich, Switzerland, Current Biology, “Acoustic Communication: Sound Advice
from Piranhas”
WAZA.org –
Red Bellied Piranha
Wikipedia: Red
Bellied Piranha
Zollinger, Sue
Anne, “Piranha – Ferocious Fighter or Scavenging Softie?” 3 July 2009
