Owing to its deepwater habitat, very few observations of the frilled shark have been made in its natural environment (8). Analysis of stomach contents of frilled sharks brought to the surface indicate that this species mostly preys on deep water squid and a variety of fish, including other sharks (1). While it is unclear exactly how the frilled shark feeds, its set of needle-sharp, inwardly-pointing teeth, and the fact that its jaws can open extremely wide, suggest that it may actively take prey over one and a half times its own length (1) (4). Interestingly, this species has also been found higher in the water column at depths between 50 and 200 metres, where it feeds on faster-swimming squid, although these may be taken as carrion or when the squid are exhausted after reproducing (7).
The frilled shark, like many other sharks, is ovoviviparous, which means that after fertilisation, the embryos develop within the female’s uterus, receiving nourishment from a yolk sac. Once the yolk sac nutrients are exhausted the embryos absorb nutrients from secretions within the uterus until birth takes place. The litter is very small, numbering only two to ten offspring, which each measure between 40 and 60 centimetres in length. Studies of frilled shark embryos indicate that this species could have a gestation period of over 3.5 years, which, if accurate, would be the longest known amongst the vertebrates (2).