Australian and Mediterranean Great White Sharks Have the Same Ancestry

Luck pays a large part in evolution. Climate suddenly changes and if by chance a species of animal carries suitable genes to flourish in the new environment that animal lives on. Other species die off because they cannot cope.

New findings about the great white shark highlights this. Australian great whites and the Mediterranean type have genes that point to common ancestry. It is believed that a few related female sharks split up. Some going north to the Mediterranean from the larger gene pool in the south, or they peeled off from the main group in the Atlantic some going north the others going south. Narrow channels in the Mediterranean stopped this group from rejoining the Australian gene pool.

This happened 450,000 years ago. Mutations since that time make the timeline clear. It is believed that swordfish and tuna the main food of the great white also split off from the their main groups. Great white sharks followed the food supply.

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Fish Are Intelligent and Can Remember

For years scientists told us what we wanted to believe - that fish have short memories in line with one lap of the fish bowl. Now the truth has got out. They are intelligent creatures who can learn to do things and can even deceive other animals. Once attacked, if they escape, they remember which predator tried to kill them. Unlike humans, however, there is a cost when they use they intelligence. If they are given one fish for food they are very efficient in catching it, but if given two types of prey they apparently become confused and their effectiveness declines.

Fish interact in a social way. They recognize familiar others and modify their behavior accordingly. Siamese fighting fish will take advantage of a weak fighter by observing fish fights and readily attacking the weaker fish. Fish that clean others act busy when potential "customers' are watching. In a way they advertise.

The myth about fish having no memory or even intelligence is most likely promulgated to justify fishing, when fishermen say it is alright to jab in a hook or gut a fish because they don't feel any pain.

An example of fish learning occurred when Professor Charles Erikson fed fish after calling to them by saying "fish-fish". When he returned five years later he called to them and some fish came to the surface expecting food. Other examples include trigger fish which use tools to trick prey that hunt them, and frillfin which jump back into rock pools to avoid birds.

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