Définition : A hard, thorny or needle-like structure which occurs on various organisms. Animals such as porcupines and sea urchins grow spines as a self-defense mechanism
Définition : This organism produces this material or substance, either during its life or after death. A produces B if some process that occurs in A has output B.
Définition : A group of species that exploit the same food resources, and/or use the same feeding or foraging methods. http://en.wikipedia.org/wiki/Guild_(ecology)
