Chimaeras, also called ghost sharks or rabbit fish, are deep-sea fish related to sharks, skates, and rays. They have unique features like fused upper jaws, four gills, and large grinding tooth plates, and live at depths of 200-2,600 meters. Chimaeras feed mainly on bottom-dwelling invertebrates, use electroreception to hunt, and lay eggs in sandy or muddy sea beds. They are vulnerable to fishing pressures and deep-sea trawling.