Scientists studying them have discovered unique and spectacular asymmetries in the salamander's jaw and the hyoid movements made during this rapid suction feeding. Depending on the position of the prey, the animal can rapidly and forcefully open and close one side of its mouth independently and bend its mandible forward by as much as 40 degrees. This action generates the necessary force to capture prey, and Maruska has seen an unwary keeper's finger badly mangled by a giant salamander. Giant salamanders are unusual for amphibians in that they lay their eggs in early autumn. As a result, fights often occur between males over access to this scarce resource.
Males lose toes and limbs in the battles and some die from bites to their heads and necks.
According to Kazushi Kuwabara, past director of the Asa Zoo in Hiroshima, Japan, an elaborate mating ritual takes place when a gravid female visits a nest to lay her eggs. Shortly before she produces her bead-like string of light yellow eggs in transparent jelly, the female starts to turn and spin with the resident male. Other males are allowed into the nest to join the spinning pair as the female arches her back and starts releasing eggs for the males to fertilize. The spinning amphibian mass accelerates until the eggs are spawned and slows as the males cover the eggs with milt. This process repeats until the female has deposited all of her 400 to 500 eggs, then departs.