The International Union for the Conservation of Nature (IUCN) lists 9 species of spider monkey, which can be found in rain forests from southern Mexico through Brazil. The IUCN lists 3 spider-monkey species as Critically Endangered; 5 species of spider monkey are listed as Endangered, and 1 species is Vulnerable.
The foundations of the endocrine system are hormones and glands. A gland is a group of cells that produces and secretes hormones. Hormones are the body's chemical messengers. They send and relay messages between different systems. Many different hormones move through the bloodstream.
A chemical messenger is any compound that serves to transmit a message. A chemical messenger may refer to: 1  Hormone, Long range chemical messenger. 2  Neurotransmitter, communicates to adjacent cells.3  Neuropeptide, a protein sequence which acts as a hormone or neurotransmitter. chemical messenger is any compound that serves to transmit a message. A chemical messenger may refer to: 1  Hormone, Long range chemical messenger. 2  Neurotransmitter, communicates to adjacent cells.