Questions and answers
- Where do sharks live?
In all the oceans of the world, exept possible the coldest waters of
the Antarctic. They inhabit a broad range of habitat from the warm tropical
and subtropical waters to the cold and ice waters of the Arctic. A few
species inhabit brackish water of estuaries and the freshwater of tropical
lakes and rivers.
- How old do sharks get?
Some species may live for almost a century (the spiny dogfish), but
the average life span is less than 25 years. Most of that we know about
the life span of sharks comes from records of sharks in captivety or
from tagging or recovery programs. These data show that the maximum
age attained varies according to the species. The life span for most
of the known species is very uncertain and should not be taken as absolute.
- What do sharks eat?
Sharks are flesh eaters, feeding mainly on crustaceans, fishes and mollusks.
Some, perhaps most are generalists, eating whatever food is available,
which includes not only fishes and marine invertebrates, but marine
turtles, mammals, birds, and even such unlikely objects as tin cans.
Not all sharks eat large organisms as those mentioned above. Some of
the biggest sharks, like the whale shark and the basking shark are filter
feeders, dining on plankton, tiny shrimps and small fishes.
- Must sharks swim to breathe?
A common but erroneous idea is that sharks can breathe only when swimming.
This is true of many, if not most sharks, but there are some that do
not have to swim with open mouth to breathe. Some sharks do appear to
respire by swimming, but others, like the nurse, lemon and bull shark,
breathe activly, pumping water over their gills by opening and closing
their mouth even when not swimming. Many species, usually bottom dwellers
use the spiracle (opening behind the eye) to pass oxygenated water to
the gills.
- Which shark is the biggest?
The whale shark is the biggest shark and also the largest fish known,
living or fossil. This species has been reliably measured at over 12
m, but is known to grow much larger, possibly to 18 m (59 ft.).
- Do sharks have enemies?
Some sharks pray on other sharks, but it is people who are sharks' greatest
enemies. Stomachs of large bony fishes and killer whales occasionally
yield the remains of small sharks, but much more often, large sharks
will eat smaller ones.
- Are sharks dangerous?
Sharks do attack humans and are a potential threat to the life of anyone
who spends time in the water. However, the risk of being attacked is
not great. Less whan 100 attacks are reported worldwide each year, and
no more than 30 are fatal.
- Which sharks are dangerous?
The four most dangerous sharks, which are those that always pose a danger
to humans and have a record of numerous attacks with several fatalities,
are the white shark, tiger shark, bull shark, and ocean whitetip shark.
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