The morphology of the pit organs and lateral line canal neuromasts of Mustelus antarcticus (Chondrichthyes: Triakidae)

• Published in: Journal of the Marine Biological Association of the United Kingdom
• Main Authors: Peach, Meredith B., Rouse, Gregory W.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2000
• Subjects: Aquatic Science; Antarc*; antarcticus
• Online Access: http://dx.doi.org/10.1017/s0025315499001678; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0025315499001678

The pit organs (free neuromasts) of sharks are part of the lateral line sensory system, but there is still confusion about their exact morphology and function(s). This is partly because of reported physiological differences between the pit organs and the lateral line canal neuromasts, and partly because the morphology of pit organs has not been adequately documented. To compare their morphology, the pit organs and canal neuromasts of the gummy shark Mustelus antarcticus (Chondrichthyes: Triakidae) were examined using transmission and scanning electron microscopy. Both pit organs and canal neuromasts had hair cells with the `staircase' arrangement of sensory hairs (stereovilli) characteristic of vertebrate mechanoreceptors. Stereovilli bundles of different sizes were distributed haphazardly throughout the pit organs and canal neuromasts. The density of hair cells was similar in the pit organs and canal neuromasts, but differences in the overall size and/or shape of the sensory epithelia might account for some of the reported differences in mechanosensitivity.