Distinct startle responses are associated with neuroanatomical differences in pufferfishes

Area of Science:

• Neuroethology
• Comparative Anatomy
• Evolutionary Biology

Background:

• Mauthner cells (M-cells) are critical for initiating rapid escape responses in fish.
• M-cell loss is observed across teleost phylogeny, but behavioral consequences are understudied.
• Pufferfishes exhibit potential variability in M-cell anatomy.

Purpose of the Study:

• To investigate the correlation between M-cell anatomy and fast-start escape behavior in pufferfishes.
• To compare M-cell presence and function in Tetraodon nigroviridis and Diodon holocanthus.
• To understand the impact of M-cell variation on survival behaviors.

Main Methods:

• Characterization of M-cell anatomy using retrograde labeling and anatomical techniques.
• Assessment of fast-start responses to tactile and acoustic stimuli.
• Behavioral analysis of escape latency and extent in two pufferfish species.

Main Results:

• Tetraodon nigroviridis possesses M-cells and exhibits robust, rapid fast-start responses.
• Diodon holocanthus rarely displayed fast-start behavior, with significantly longer latencies.
• No clear M-cell candidates were identified in Diodon holocanthus using multiple anatomical methods.

Conclusions:

• A strong correlation exists between the presence of Mauthner cells and the capacity for rapid escape behavior in pufferfishes.
• The absence of M-cells in Diodon holocanthus corresponds to a lack of effective escape responses.
• Pufferfish diversity offers a model for studying the evolution of M-cell-mediated behaviors.