Gioca STEMAnimals

Animals · Rivers, lakes and wetlands

Piranha

Pygocentrus nattereri

A timid scavenger rather than a monster

An adult Piranha with silvery scales and a reddish belly typical of the species in freshwater habitats.
An adult Piranha with silvery scales and a reddish belly typical of the species in freshwater habitats.
  • Status: Safe
  • Tropical rivers of South America, from the Amazon basin to the Essequibo

Numbers

Weight
8,6 lbmaximum weight; specimens often remain smaller
Length
20 inmaximum; most specimens do not exceed 14 in
Lifespan
10 yearsup to 10 years in the wild
Eggs per spawn
5000 eggsabout, in a single clutch
Call frequency
1740 Hztype 3 call, linked to chasing
Minimum temperature tolerated
50 °Fonly for a limited period

Ten fun facts

  1. the teeth of the Piranha are extremely strong and replaced one by one continuously, ensuring the fish always has an effective bite.

  2. when pulled out of the water it produces a drumlike sound, and researchers have identified three distinct types of acoustic calls.

  3. in certain studies, Piranhas frightened by a simulated attack calmed down much faster in groups of eight than in pairs.

  4. spawning happens during two seasons each year, triggered by water levels, flooding, and temperature changes rather than a fixed calendar.

  5. when a Piranha is ready to breed, its red belly fades and it seeks sheltered waters among submerged plants and flooded forests.

  6. in August 2009 a large fish was caught in Italy, likely released from a private aquarium, though it could not survive winter.

  7. young fish raised together often bite each other's fins, a behavior called fin nipping, but damaged fins regrow surprisingly fast.

  8. goldfish used as live food in aquariums contain a hormone that slows growth, which can also reduce the growth of Piranhas.

  9. the 1978 movie Piranha portrayed it as a bloodthirsty monster, an exaggerated reputation for a creature that mainly scavenges for food.

  10. it can reach twenty inches and nearly nine pounds, but usually stays under fourteen inches, making it a relatively compact species.

The quiz answers

Five questions about this animal. Pick an answer and find out if it is the right one.

Question 1 of 5

How does the Piranha usually behave compared to its reputation?

Question 2 of 5

Why does the Piranha form shoals even as an adult?

Question 3 of 5

About how many eggs does a female lay in one spawn?

Question 4 of 5

What is the maximum length a Piranha can reach?

Question 5 of 5

How many different types of sounds do Piranhas produce according to studies?

Try it yourself

Experiment 1

Measure fourteen inches on a ruler to see the typical length of an adult Piranha. Compare this size with a standard notebook or a long pencil.

Experiment 2

Fill four one liter bottles with water and lift them together. They weigh about the same as a large Piranha at its maximum weight of nine pounds.

Experiment 3

Count aloud to one thousand and repeat that five times. This equals the approximate number of eggs a female Piranha lays in a single nest.

Data from Wikidata (Q928382) and Wikipedia (Red-bellied piranha).