Exohormone

Exohormone is a term sometimes used to describe chemical substances released by organisms that influence the behavior or physiology of other organisms of the same species. This concept is closely related to pheromones, which are specifically defined as chemical signals that trigger a social response in members of the same species. The term "exohormone" was introduced to broaden the scope beyond just social behaviors, potentially encompassing a wider range of inter-organismal chemical communication.

While pheromones are well-established and extensively studied in various animal species, the concept of exohormones is less formally defined and less commonly used in scientific literature. The distinction, if any, lies in the breadth of effects. Pheromones are typically associated with direct, often rapid, behavioral changes like mating attraction, alarm signaling, or territorial marking. Exohormones, in a broader interpretation, could include substances that affect a wider array of physiological processes or have a more indirect or long-term impact on the recipient.

Examples often cited under the umbrella of pheromonal communication, and thus potentially exohormonal, include sex attractants released by insects, alarm substances from fish, or trail pheromones used by ants. The underlying principle is the transmission of information through external chemical cues. The study of these substances falls under the field of chemical ecology, which investigates the role of chemical interactions in ecological relationships. The precise definition and usage of "exohormone" remain fluid, with many scientists preferring the more precise and widely accepted term "pheromones" for most of these phenomena.