Vampire squid
The Vampire Squid likely reproduces slowly by way of a small number of large eggs. Growth is slow as food is not abundant at depths where the animals live. The vastness of their habitat and its sparse population make procreative encounters a fortuitous event. The female may store a male's hydraulically implanted spermatophore (a sort of tapered, cylindrical satchel of sperm) for long periods before she is ready to fertilize her eggs. Once she does, she may need to brood over them for up to 400 days before they hatch. The female will not eat towards this culmination and dies shortly thereafter.