sloth unleashed

Black Piranha - Serrasalmus rhombus

The black piranha (also known as the redeye or rhombeus piranha) has recently been discovered to have a bite force as strong as the estimated force of the extinct Megapiranha.

Though the negative stigma towards piranhas is largely undeserved, the mature black piranha is one of the most aggressive fish. This is especially true recently, with the over-fishing of the Amazon and Orinoco rivers, depleting the food sources of the adult fish.

Most species of juvenile piranhas feed on the scales and fins of others fish. Yes, they will swim up to, and rip the fins off of big fish, especially as they near maturity, but are not yet large enough to reliably hunt down other fish.

Despite their huge size (up to 1 m long, four times longer than adult black piranhas) and extremely strong bite force, the Megapiranha of the Pleistocene era (8-10 mya) wasn’t believed to have a solely carnivorous diet. Their saw-shaped teeth bear similarities to the Serrasalmus genus, but also to the teeth of the Pacu, or “vegetarian piranha”.

Expédition dans les parties centrales de l’Amérique du Sud, de Rio de Janeiro à Lima et de Lima au Para. Under direction of  Le Comte Francis de Castelnau, 1856.

Black Piranha - Serrasalmus rhombus

The black piranha (also known as the redeye or rhombeus piranha) has recently been discovered to have a bite force as strong as the estimated force of the extinct Megapiranha.

Though the negative stigma towards piranhas is largely undeserved, the mature black piranha is one of the most aggressive fish. This is especially true recently, with the over-fishing of the Amazon and Orinoco rivers, depleting the food sources of the adult fish.

Most species of juvenile piranhas feed on the scales and fins of others fish. Yes, they will swim up to, and rip the fins off of big fish, especially as they near maturity, but are not yet large enough to reliably hunt down other fish.

Despite their huge size (up to 1 m long, four times longer than adult black piranhas) and extremely strong bite force, the Megapiranha of the Pleistocene era (8-10 mya) wasn’t believed to have a solely carnivorous diet. Their saw-shaped teeth bear similarities to the Serrasalmus genus, but also to the teeth of the Pacu, or “vegetarian piranha”.

Expédition dans les parties centrales de l’Amérique du Sud, de Rio de Janeiro à Lima et de Lima au Para. Under direction of  Le Comte Francis de Castelnau, 1856.

Thornback ray (Raja clavata) and thornback ray skeleton

Like sharks, rays and skates have fully cartilaginous skeletons, which provide a stable structure but more flexibility than bone. You can see that, much like fish, rays have defined, er, rays, in their fins. The difference is that while fish tend to have a few unconnected rays and a taught tissue between them, the Rajiforms (skates and rays) have many, many rays, which are all connected perpendicularly by collagen. The body is then formed around these rays, which propel the Rajiforms forward in an undulating (wave-like) motion.

A history of the fishes of the British Islands. Jonathan Couch, 1863.

Thornback ray (Raja clavata) and thornback ray skeleton

Like sharks, rays and skates have fully cartilaginous skeletons, which provide a stable structure but more flexibility than bone. You can see that, much like fish, rays have defined, er, rays, in their fins. The difference is that while fish tend to have a few unconnected rays and a taught tissue between them, the Rajiforms (skates and rays) have many, many rays, which are all connected perpendicularly by collagen. The body is then formed around these rays, which propel the Rajiforms forward in an undulating (wave-like) motion.

A history of the fishes of the British Islands. Jonathan Couch, 1863.

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