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What is the role of the cupula in a fish’s lateral-line system?
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Mechanoreception
In human skin, specialized nerve endings known as Meissner's corpuscles (or tactile corpuscles) are sensitive to touch. They are one of several different types of mechanoreceptors found in human skin.
In a fish’s lateral-line system, the cupula serves as a critical component of the neuromasts, which are the system's primary mechanoreceptors.1
The cupula is a jellylike sheath that encapsulates a cluster of sensory hair cells and their supporting cells. Its role is to act as a mechanical intermediary between the surrounding water and the sensory receptors:1
- Transduction of Movement: When water moves or pressure changes occur in the environment, the cupula is displaced.12
- Stimulation of Hair Cells: This displacement of the jellylike cap causes the tiny hairlike processes (cilia) beneath it to bend.12
- Signal Generation: The bending of these hairs triggers the sensory cells to fire, sending electrical signals to the fish's nervous system.2
By translating water displacement into physical movement of the hair cells, the cupula allows the fish to detect the rate and direction of water currents, helping it sense its own movement, the presence of nearby predators or prey, and the location of stationary objects.12