Bristlemouth (IMAGE) University of Washington Caption A bristlemouth in the family Gonostomatidae, mesopelagic fishes that undergo daily vertical migrations. Credit Steven Haddock/Monterey Bay Aquarium Research Institute Usage Restrictions No restrictions. License Public Domain Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.