The generic name refers to one of the Three Fates, Lachesis (in Greek mythology), who determined the length of the thread of life.

[2] Its evolutionary relationships are not certain, but Lachesis acrochorda is thought to be closer to L. muta than to the two Central American species L. stenophrys and L. melanocephala.

Lachesis is thought to be unique among New World pit vipers by laying eggs rather than giving birth to live young, although some evidence suggests that the species Bothrocophias colombianus found in Colombia may do the same.

It also has coagulant activity in which thrombin-like enzymes act on fibrinogen, forming small clots that settle in organs such as lungs and kidneys, obstructing capillary blood flow.

Proteolytic activity is due to direct action of proteases (thrombin for example), metalloproteases, and important myotoxic and cytolytic factors.

Myotoxic action occurs due to phospholipase generating an inflammatory infiltrate composed of polymorphonuclear leukocytes and macrophages around necrotic cells.

The venom also has a neurotoxic action, isolated from basic phospholipase, that is capable of inducing irreversible blockage of neuromuscular transmission in vitro at concentrations as low as 1 mg/ml.