[BlueTrend Classroom] Beautiful Predators — A Field Guide to Sharks

the Editor says: Sharks — the crown jewel of every diver's wish list — first appeared on Earth some 420 million years ago. Since then, they have evolved into more than 500 distinct species, ranging from the Whale Shark, which can grow as large as a truck, to the dwarf lanternshark at just 30 cm. Despite this incredible diversity, most divers know surprisingly little about shark behaviour. Reading Beautiful Predators — A Field Guide to Sharks is sure to open the door to the mysterious world of sharks!

Beautiful Predators — A Field Guide to Sharks

Most people's impressions of sharks come straight from the movies — from the 1975 American blockbuster Jaws to the more recent The Meg — where directors have cast sharks as the ultimate symbol of terror. Yet for us divers, sharks inspire an almost inexplicable longing. Many people spend enormous sums travelling abroad on dive trips just for the chance to swim alongside Hammerhead Sharks. But out of the 500-plus shark species in the world, how many do you actually know?

The truth is, sharks come in a remarkable variety — not just the fearsome great white from Jaws, but also the Whale Shark (Rhincodon typus), the largest of all fish; the epaulette shark (Hemiscyllium ocellatum), which uses its pectoral and pelvic fins to "walk"; the Japanese bullhead shark (Heterodontus japonicus), a common sight in aquariums; the blotchy swell shark (Cephaloscyllium umbratile), whose embryos are visible right through the egg case; and the scalloped Hammerhead Shark (Sphyrna lewini), whose head is shaped like a mallet. All told, there are more than 500 shark species worldwide.

Beautiful Predators — A Field Guide to Sharks opens with an extensive section profiling 66 of the more commonly encountered species — including the Whale Shark, Hammerhead Shark, great white, and silvertip shark — using photographs and text to explain each species' unique behaviour (habitat, diet, hunting strategy, and more), as well as the all-important question of whether that species will actually bite a human. For anyone wanting to get to know sharks, this book is an indispensable field guide.

How are sharks classified? What structures make up a shark's body? In what era did sharks first appear? Understanding these fundamentals helps us grasp the taxonomy and phylogenetic relationships of sharks. The book also covers ecology in depth — diet, movement, habitat, natural predators, reproduction, and lifespan. As apex predators at the top of the food chain, sharks prey on organisms lower in the hierarchy, and the animals they take are typically the weakest individuals in a given population. The law of the jungle governs the natural world: even the great white shark, which strikes terror into the hearts of humans, is but a small piece of a vast tapestry — yet it is one of the most critical links in maintaining healthy marine ecosystems.

After the shark profiles, the author thoughtfully includes a guide to 21 aquariums across Japan where visitors can see sharks up close. There are also substantial sections on the history of sharks in cinema and on how the Japanese have used sharks in traditional crafts and daily life throughout the centuries — so the book offers insight not just into the animals themselves, but also into the long and complex relationship between sharks and human civilisation.

In some countries, fishermen cut off only the shark's fins and discard the rest of the body at sea, resulting in enormous waste. According to the 2015 IUCN Red List of Threatened Species published by the International Union for Conservation of Nature (IUCN), as many as ten shark species are listed as Critically Endangered (CR) — meaning they face an extremely high risk of extinction in the near future (equivalent to Japan's Ministry of the Environment Category IA). A further fourteen species are listed as Endangered (EN), facing a very high risk of extinction (Japan's Category IB). In short, sharks are apex species; a stable, diverse shark population in a given sea area is, to some extent, a sign that the local ecosystem is in good health. (It is hard not to feel a pang of sadness when one realises that sharks are almost entirely absent from most dive sites in Taiwan.)

Humans have long exaggerated the threat posed by sharks. According to US statistics, only 26 people died from shark attacks between 1959 and 2010 — an average of just 0.5 deaths per year. By contrast, obesity-related deaths in the same country number around 150,000 per year — over 25,000 times higher. The statistical risk of being fatally attacked by a shark is, by comparison, vanishingly small.

What Should You Do If You Encounter a Shark?

The book does, however, share some self-defence tips in the unlikely event that a shark takes an interest in you:

• Stay calm and get to shore or back onto the boat immediately.

• Keep your eyes on the shark at all times — do not turn and swim away. You can use a stick to threaten it or create air bubbles to drive it off.

• If the shark does attack, fight back by striking its eyes or gills to frighten it.

• If you successfully repel the shark, do not let your guard down — stay alert in case it circles back for another attack!

Finally, the book covers various shark behaviours, including hunting habits and the reproductive process. Perhaps the most fascinating section is on shark body language — it turns out that sharks, not unlike cats, have a whole set of pre-attack behavioural cues that follow a distinct sequence!

If you, like the Editor, are a shark-chaser at heart, this book is highly recommended as a keeper — a deep dive into one of the ocean's most ancient and mysterious species!

(Excerpt adapted from Beautiful Predators — A Field Guide to Sharks, published by Morning Star Publishing. Cover image source: Pxhere, CC licensed.)