420 Dive Log Australasia OCTOBER 2026

This principle applies to all life forms, including people. Some people have strong immune systems while others get a cold far too often. Every person has variations in skin, blood type, hormone levels and most parts of their anatomy. What this means is every life form reacts to changes in differing

ways. Take dehydration for example. Some people can survive without drinking for a few days and then they die. Others can survive without drinking for a week There may be someone who can survive for ten days. Variation to dehydration and being deprived of water allows some individual to survive better than others. This is Natural Selection.

An illustration of ENVIRONMENTAL PRESSURE Weedy Sea Dragons are quite defenceless. Here we see a male Weedy with a fresh batch of eggs. Below, a nasty Wrasse has charged in at speed and bitten off a mouthful of nutritious eggs. Ouch!

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Dive Log Australasia #420 October ’26

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