A powerful and versatile predator, the broadnose sevengill shark takes a wide variety of prey, including marine mammals such as dolphins and seals, and fish including sharks, salmon, sturgeon and herring (2). It has also been known to feed upon shark egg cases, sea snails, and the dead bodies of mammals it find in the water, such as rats and humans (3). Interestingly, this species will sometimes hunt in groups, with the individual sharks working together to capture large, agile prey such as marine mammals (2). At other times, it hunts stealthily, making very little body movement except small undulations of the caudal fin, before making a rapid dash when within striking distance (2) (4). While regarded as potentially dangerous to humans, attacks are very rare, usually only occurring when the shark is provoked (2) (3). Although a formidable predator, the broadnose sevengill shark sometimes falls prey to larger sharks such as the great white (Carcharodon carcharias), and has been known to be cannibalistic (2).
Like many shark species, the broadnose sevengill shark employs a mode of reproduction termed ovoviviparity. This involves the fertilised eggs hatching within the female’s uterus, where the embryos then develop, 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. In this species, the gestation period—from egg fertilisation to birth—takes around one year, with the young born during spring and early summer, usually in a shallow bay area (2). Litters may number between 82 and 95 pups, with each measuring around 40 to 45 centimetres in length (2) (3). The young remain in shallow water nurseries for several years before moving to deeper, offshore regions (2).