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"Poisonous" does not mean deadly. Some manifestations of toxicity are subtle. The dose, as always, determines if a plant is safe source of nutrients or a toxic hazard.

Cyanide eating Bamboo Lemurs live to tell the tale...

Madagascar, an island off the southeast coast of Africa, is home to the group of primates known as the lemurs. Unique to Madagascar, these animals are thought to resemble the primitive ancestor of today's monkeys and apes. There are over 35 species of lemur living in Madagascar, inhabitaing a variety of natural habitats, from rainforest to desert like plains. Among these are the genus Hapalemur or the Bamboo lemurs. There are three species of Bamboo lemurs: the Greater Bamboo Lemur (H. simus), three subspecies of the Lesser or Gentle Bamboo Lemur, (H. griseus), and the Golden Bamboo Lemur, (H. aureus), who has the dubious honor of being the world's most recently discovered primate, having been found by Dr. Patricia Wright of SUNY Stonybrook in 1984.

These three sympatric species inhabit the same habitat and feed on the same bamboo species, Cephalostachyum cf viguieri and C. perrieri. How then is major competition avoided? It turns out that each species eats a different part of the bamboo. H. simus prefers the woody pulp and culms of C. cf. viguieri, while H. griseus eats the leaf bases of both species and selects the shoots of C. perrieri. H. aureus meanwhile eats only the shoots of C. cf. viguieri. The question then arises, what prevents the H. griseus from encroaching on the territory of their cousins by eating the shoots of both bamboo species?

The answer is simple: cyanide. The shoots of C. cf. viguieri contain 15 mg of cyanide per 100 g of fresh weight. The H. griseus stay away from the shoots of this plant because they are highly toxic. On the other hand, the Golden Bamboo Lemur eats an average of 500 g of this cyanide laden bamboo every day, thus intaking an estimated 12 times the toxic dose for a primate of its body mass. Unfortunately, the mechanism H. aureus uses to detoxify this poison is as yet unknown. However, large amounts of cyanide have been measured in the feces which are the food source specifically selected by a species of dung beetle who seems to have co-evolved with the Golden bamboo Lemur.