Vampire squid reproductive strategy is unique among coleoid cephalopods

Coleoid cephalopods are thought to go through only one reproductive cycle in their life. We here report that vampire squid (Vampyroteuthis infernalis) show evidence of multiple reproductive cycles. Female vampire squid spawn their eggs, then return to a resting reproductive state, which is followed by the development of a new batch of eggs. This reproductive cycle is likely to be repeated more than twenty times. This combination of reproductive traits is different from that of any other extant coleoid cephalopod. Extant coleoid cephalopods (all living cephalopods, except the chambered nautilus) are semelparous — an individual undergoes only a single reproductive cycle after which it dies. This reproductive strategy is different from iteroparity, whereby an individual has multiple reproductive cycles [1]. Although some cephalopod species may grow between spawning events or spawn multiple egg batches [2], extant coleoid cephalopods do not have a gonadal resting phase. In iteroparous fi shes, the gonadal resting phase includes the period when spawned adults have no growing oocytes or ripe eggs in the ovary [3]. The notion that all coleoid cephalopods are semelparous was recently challenged by observations of the fi rst known carcass of a mature female of the oceanic squid Kondakovia longimana [4]; however, conclusive evidence of iteroparity in a coleoid cephalopod had been absent to date. We investigated the reproductive strategy of the vampire squid (Figure 1). This coleoid cephalopod occurs at open ocean depths between 500 and 3000 m and is able to inhabit low oxygen environments [5]. Vampire squid feed opportunistically on zooplankton and detritus [6]. Young [7] observed that in adult females, developing eggs were present in various sizes Correspondence