DIVE LOG Australasia

Tiger shark feeds provide invaluable data in the research into shark reproduction.

• 2. Full intra-uterine cannibalism Finally, there is the most gruesome form of all, displayed in the Grey Nurse. The largest foetus eats its smaller siblings inside the womb. After cannibalising its brothers and sisters, it continues to consume eggs as it develops into a super baby. Baby Grey Nurse sharks are born at about one metre in length There are powerful evolutionary advantages for this form of nourishment of the baby sharks. Firstly, it removes opposition. Monster baby has one chance at life but it has stacked the deck in its favour. Secondly, the single baby when born is a fully

developed giant. It is powerful and well able to take care of itself in the wild from day one. The evolutionary pressure here is the high mortality of baby sharks. Remember the Tiger shark has up to eighty babies. Most are eaten by Cod, Groper, Sea Snakes and sharks in the first few weeks. Bigger babies solve this problem! Detailed knowledge of marine life gives us a much greater appreciation of the sea. It improves your enjoyment of diving. After all, when I look back on the day I finished my open water scuba course, I hardly knew anything.

Sub-adult non-breeding Great White shark. Females do not breed until they are 15 to 20 years old.

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DIVE LOG Australasia #408 - October ‘24

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