Unusually for salamanders, hellbenders engage in external fertilisation. Male hellbenders will seek out the perfect flat rock under which to dig a nesting burrow, and will defend it viciously from other males. When a female approaches, the male will coax her inside to lay her eggs, which he will then fertilize. A single female can lay up to 200 eggs, connected by five cords, and one male’s burrow can contain almost 2000 eggs at once. The male will guard the eggs in the two or three months it takes them to hatch, standing over them and rocking his body and undulating his skin folds to keep water flowing over his clutch, keeping them oxygenated. When the larvae hatch, they are all but limbless and subsist on a large yolk sack for their first few months of life.
Sadly, the larvae have little chance of making it to adulthood. Aside from the adult hellbenders’ tendency towards cannibalism, hellbender larvae are particularly vulnerable to pollution and rising silt levels. Some zoos, such as the Toledo Zoo, are now raising hellbenders until they are about a year old before releasing them to the wild, greatly increasing their chance of survival.
(via koryos)