Final answer:
Multicellular organisms use four main types of signals for communication: chemical (pheromones), aural (sound), visual (displays), and tactile (touch). These signals facilitate a wide range of interactions within species, from courtship to marking territory.
Step-by-step explanation:
When discussing the types of signals used by multicellular organisms to communicate, we can identify four main categories: chemical (pheromones), aural (sound), visual (courting and aggressive displays), and tactile (touch).
Chemical signals, or pheromones, are substances that are released by an organism into the environment and cause a response in another individual of the same species. Aural signals are auditory communications like bird songs or whale vocalizations used for varied purposes, such as attracting a mate or defining territory. Visual signals include varied forms of courtship or threat displays that may involve color patterns, movements, or body postures. Lastly, tactile signals involve direct contact between individuals, such as touching, grooming, or nudging, to convey messages.