32 33 Hagfishes are the most ancient of the extant craniates, and demonstrate a 34 high tolerance for a number of unfavorable environmental conditions including 35 elevated ammonia. Proposed mechanisms of ammonia excretion in aquatic 36 organisms include vesicular NH4+ transport and release by exocytosis in marine 37 crabs, and passive NH3 diffusion, active NH4+ transport and paracellular leaka...
