Here at Rachel Brooks Art you know we are obsessed with all things shark, so what better way to kick off shark week than by sharing some new shark news and discoveries!
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There are over 500 species of shark described but even in 2023, we are still discovering new species. Sharks have roamed our oceans for over 400 million years, humans have only shared the earth with them for a small fraction of this time and we still have so much to learn about these incredibly diverse animals.
There are over 500 species of shark described but even in 2023, we are still discovering new species. Sharks have roamed our oceans for over 400 million years, humans have only shared the earth with them for a small fraction of this time and we still have so much to learn about these incredibly diverse animals.
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New deep-sea cat shark discovered in Australia!
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Sharks have various methods of reproduction; viviparity, giving birth to live young, ovoviviparity, where young develop in eggs within the womb and oviparity when eggs are laid and develop in the water. Around 40% of all sharks are oviparous with the eggs developing in leathery cases also known as mermaids purses. And these mermaids purses are the first clue to the puzzle. 
In the late 1980s, scientists found a mysterious egg case, it had a unique row of ridges along the top, leaving the question of which shark laid it?
Over thirty years later the problem was finally solved - and it just took looking at the pieces again with a fresh set of eyes. Knowing the egg case samples had come from depths of around 400-500 metres the team started to look through the archives for sharks which had been recovered from similar depths. A shark specimen which had been previously misidentified as a South China catshark was, in fact, pregnant, and upon inspection, the same strange eggcases were found inside her! Making this the confirmed discovery of a new shark species, now formally known as, Apristurus ovicorrugatus.
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Who knows how many more mysteries of the deep there are to uncover?
Read more about this exciting discovery here
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Basking sharks found to be regionally endothermic
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Basking sharks, Cetorhinus maximus, are the second largest fish in the world. Being one of only three known plankton eating sharks, these unusual fish lead mysterious lives. Only appearing in large aggregations each summer in Scotland and Ireland, scientists are still making discoveries about these elusive animals, and there have been many breakthroughs in recent years.
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Spending most of their lives in deeper water, studying basking sharks has always been complex, especially after their population was decimated by hunting across the globe. These slow moving animals had been assumed ectotherms, or 'cold blooded' along with almost all other fish, meaning their internal temperature is regulated by their external surroundings. But there are a small number of fish, notably fast moving predators such as the tuna and great white shark which are capable of regulating their own internal body temperature. This is a unique trait amongst fish, currently only recognised in as few as 0.1% of species. These species tend to swim faster than there similarly sized ectothermic counterparts.
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Dissection of two basking shark samples in the UK by an international team of researchers led by Trinity College Dublin, found physiological traits similar to those observed in other regional endotherms. Tag data confirmed their findings that the sharks' body temperature was consistently higher than the surrounding water. With the lifestyle of a basking shark being so different to the other mackerel sharks and predatory fish they share this feature with, this only leads to more questions about this enigmatic species!
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Read the research here
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Reef sharks in trouble
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Now we couldn't report on shark news without touching on the reality for a lot of shark species. Sharks across the globe are facing extinction from human pressures, with over one third of all sharks listed as endangered, and oceanic shark and ray populations falling over 70% in the last 50 years alone. These are terrifying statistics for the future of our oceans.
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Populations of the five main shark species found inhibiting coral reefs have declined further than previously thought. Grey reef, blacktip reef, whitetip reef, nurse and Caribbean reef shark populations were surveyed on coral reefs across the world over a five year international study. 22,000 hours of footage were collected from almost 400 different coral reefs across the world. The findings revealed reef shark populations in these areas had fallen by an average of 63%.
Some species were completely absent in the surveyed reefs, and where shark populations had significantly declined, ray species had increased - suggesting shifts across the entire reef system. In areas where there are enforced marine protection shark populations continued to play apex predator, but in areas with lack of management ray populations are taking advantage of the gap at the top of the food chain.
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Read the science here
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Shop to support shark conservation? Visit my collaboration with Saving the Blue which donates 20% of the profits to supporting shark research and conservation.
