Broadnose Sevengill Shark
Threat Level: low
The Broadnose Sevengill Shark is
also known as bluntnose sevengill
shark, broad snouted sevengill, broadnose sevengill shark,
broad-snout, cowshark, ground shark, Pacific seven-gill shark,
seven-gill cowshark, sevengill shark, seven-gilled shark,
spotted cow shark, spotted seven-gilled shark,
and Tasmanian tiger shark.
- BROADNOSE SEVENGILL SHARK
Scientific Name.... Notorynchus Cepedianus
Family Name...... Hexanchidae
- General Information: The broadnose sevengill
is a large shark that is easily recognized because of its seven
pairs of gill slits ( most sharks have five pairs ). It also has
another unusual feature and that it has a single, small dorsal
fin. It has a wide head with a short, blunt snout and small eyes.
- Size: The Broadnose sevengill are large and
powerful sharks, that can grow up to 10 feet long, and the maximum
reported weight was 234 pounds.
- Teeth: The teeth of the broadnose sevengill
sharks are very effective for cutting. The teeth of the upper
jaw are jagged with cusps, except for a single middle tooth; the
teeth on the bottom jaw are comb-shaped.
- Color: The color of a sevengill shark is quite
variable, which is an adaption that allows the shark to blend
in with its environment. The dorsal color is silver-gray to brownish,
allowing the shark to blend in with the dark marine waters. The
underside is light in color, which blends the shark in with the
surface of the water when viewed from below. This coloration pattern
is common among many species of predatory sharks. The body and
sides are speckled with numerous small dark and white spots.
- Feeding Habits: Broadnose sevengill sharks
diet consists of other sharks, seals, bony fishes, carrion, and
rays. It bites pieces of flesh from other sharks caught in gill
nets and hooks. They sneak up on their prey from behind and quickly
dashing at the last moment for the capture. One of these most fascinating
behaviours observed involves cooperative hunting by groups of these
sharks. In these events the prey, which is usually a cetacean
or a large shark and is too big for a single sevengill to handle
on its own. Groups of theses sharks will form a loose circle around
larger prey species and begin to tighten their formation as the
prey animal attempts to escape. Ultimately, one or more sharks
will rush in and attack the prey animal and this will elicit group
feeding. They are also known to be cannibals.
- Social Behaviour: The sevengill sharks sometimes
hunt in packs, working as a team to capture large prey such as
marine mammals and other sharks.
- Habitat | Migration | Distribution:
sevengill sharks are found in temperate regions of the South Atlantic,
Pacific, and Indian Oceans. These sharks prefer to live in temperate
waters on continental shelves at depths down to 450 feet. It will
often come close inshore in shallow bays and inlets. Sevengill
sharks prefer rocky bottom habitats although they commonly occur
over sandy and muddy substrates.
- Life Span: Life expectancy of this species
is about 50 years.
- Reproduction: Broadnose sevengill sharks are
ovoviviiparity bearing live young. Males mature at about 5 feet
and females at about 7 feet. The females move into shallow bays
to give birth after a 12 month gestation period. This occurs during
the spring and summer months. The litter size vary and can be
as large as 82 pups. The pups are about 16-18 inches in length
- Swimming: The majority of the broadnose sevengill
sharks will swim slowly along the bottom while occasionally cruising
to the surface.
- Broadnose Sevengill Shark Attacks:
no records of it attacking people ( except for divers in aquariums
), but it will scavenge on human corpses. It is potentially dangerous.
In captivity, it is aggressive when attacked, and it will struggles
vigorously to escape when captured.
- Population Report: Although this species is
wide spread, it is not particularly abundant.