Scientists discovered vampire squids have a sex life unlike any other known cephalopods.

Most squids reproduce only once towards the end of their lives, but the vampire squid was found to go through cycles of resting and mating similar to what is seen in fish, Cell Press reported. Vampire squids move extremely slowly, which could help explain why they do not have one large reproductive event that has a high energy cost.

"Perhaps it is therefore that vampire squid return to a gonadal resting phase after spawning, and presumably start accumulating energy for a new reproductive cycle," said Henk-Jan Hoving, who is working for the Cluster of Excellence "Future Ocean" at the GEOMAR Helmholtz Centre for Ocean Research Kiel in Germany. 

The researchers stumbled on these findings when reviewing vampire squid collections dating back to the 1960s and 1970s. They observed that females often spawned when there were no ripe eggs. The findings suggest vampire squid live longer than shallow-water squid species, and highlights how much we still have to learn about the deep ocean.

"We know very little about deep-sea organisms and their life-cycle patterns, in particular in the water column of the deep sea," Hoving sad. "The patterns we know from coastal and shallow-water organisms may not apply to deep-sea species. We need to enhance our knowledge of deep-sea pelagic organisms and the system they are part [of], since the pelagic deep sea is the largest living space on the planet. A better understanding of this unique marine ecosystem will eventually allow for better development of management and conservation strategies."

The findings were published in a recent edition of the journal Current Biology.