CARCHARODON CARCHARIAS: THE FACTS

Family:
Lamnidae (Mackerel Sharks)
Five species belong to this family: Shortfin mako, Longfin mako, Salmon shark, Porbeagle shark, White shark.

All of them have a conical snout, lateral keels (one or two) on the peduncle and homocercal tails (the tail’s upper and lower lobe are of equal length).

External Markings:
Black or dark grey on their top surfaces and white on their underside. The pectoral fins have black tips on the underside and a distinctive black axiliary spot where they join the body.

Distribution:
White sharks are found in most oceans between 50^o and 60^o latitude in both hemispheres. They prefer cooler waters, close to shore but can also be found in greater depths exceeding 1000 m.

Nursery Areas:
It is assumed that areas with higher densities indicate nursery areas (places where sharks are born), however, no birth has ever been observed.

Sexual maturity, pregnancy:
It takes females between 12 and 14 years to reach sexual maturity, males need 9 to 10 years. The fact that pregnant females are rarely found could indicate that they leave the others before giving birth. White sharks are aplacental viviparous, meaning they bear live young without connection to the mother (aplacental) during the pregnancy. To get enough nutrition while inside the mother, embryos feed on other eggs (oophagism). It is still not know how long an average pregnancy is but it may range between 12 and 14 months. The number of embryos carried during an average pregnancy can vary between 2 to 14.

Migration:
Not much is known about their migration patterns. Some experiments with satellite tags indicate that the males migrate and the femailes prefer to stay close to one place. Some sharks can stay in the same area year after year.

Social behaviour:
Although white sharks have often been portrayed as “lonely hunters”, they are social animals and can swim in groups of 10 or more animals.

Body temperature:
A few species of shark, including white sharks, are semi-warm-blooded with their blood tempertures stayng about 10 to 15 degrees Celsius above the surrounding water temperature. The prevention of heat loss is due to special arrangements of blood vessels (also known as wonder nets, or rete mirabile) found along their flanks, the eyes, brain and intestines. This higher body temperature allows the muscles to contract faster, hence increasing agility in colder water. So despite their size and weight, white sharks can accelerate quickly and reach high speeds. However, since they are semi-warm-blooded, they lack endurance compared to true warm-blooded marine animals.