THE RED-BELLIED PIRANHA FISH

This fish is well known to the public because movies and television shows have usually made piranha fish to be  senseless “killers” of any unfortunate animal that happens to be wounded and falls into an Amazon River. Some of these rumors surrounding the ferocity of this fish stem from “staged” incidents where the fish were captured, starved, and then fed meat.

Yes, this fish, and its many relatives can feed on flesh, but, piranha are classified scientifically as omnivores, which means it can eat plants and meat. Piranhas are known to be attracted by blood and activity in the water. Thus, it would not be a good idea to be thrashing about in a wild Amazon River if you have an open (bleeding) injury.

The derivation of the word “piranha” is not exactly known, but it probably stems from the words pirá [meaning fish] and ánha, meaning [cut], or sainha [meaning tooth]. In summary, piranha most likely means “biting fish.”

There are four genera and anywhere between 30 to 60 species. All of these are indigenous to the Amazon Basin in South America and its main tributaries; especially in the Venezuela and Colombia river systems, as well as in some other river systems (e.g., in Paraguay, and the coastal rivers of northeast Brazil). Most of the species are restricted to a single river system (for example, the Orinoco River System).

Adult piranhas are mostly between 5 and 14 inches long. The largest living species is the red-bellied piranha, Piranaha Pygocentrius natteri, which is illustrated below. They are the least aggressive of piranhas. Some adults of the extinct Megapiranha are up to 28 inches long.

All piranhas have a single row of extremely sharp teeth in both jaws. Their triangular-shaped teeth are bladelike, tightly spaced, finely serrated, and are interlocking (via small cusps). They are very effective for rapid puncture and shearing. Piranhas have one of the strongest bites found in bony fishes. They occur in "schools"  when hunting their prey.

Right-side view of fish. Length of fish is 8.5 inches. Its eyes are large, almost 0.5 inches wide. This allows them to see well in murky waters.

Top view of fish.

View looking directly downward into its mouth, which is 1.5 inches wide.

Oblique side view of the jaws. The opening is slightly over 1.25 inches high. The largest teeth are 1/4 inches tall. All of the teeth are pointed and, as mentioned before, extremely sharp!