Although related to the great whites that inspired Jaws – both being types of mackerel shark – and growing to 10–15 feet long, you don’t need to worry about thresher sharks attacking humans. Its prey, on the other hand – sardines, mackerel, herring, bluefish, shrimp and squid – knows it as an aggressive predator; but instead of fearing rows of flesh-ripping teeth, it’s the scythe-like tail that gives this shark its name that’s its secret weapon.

As a marine science writer, I often write about different shark species. But I do think thresher sharks are among my favourite. Here are a few fun facts, which might help you understand why.

Fun facts

• These sharks are blue-grey in colour, often with a white underbelly, and that whip-like tail which can be longer than their bodies.
• Scientists had long suspected that the shark’s weapon of choice was its tail. However, this was first observed and recorded in 2010.
• According to research by the Shark Trust, threshers are one of the few shark species to breach. Like dolphins, they leap right out of the water, possibly to try to remove parasites from their body.
• Threshers live to about 30 years old. As each litter has two pups, most females will give birth to around 40 pups during their lifetime. The first photograph of a thresher shark giving birth was taken in 2013.
• With the thresher, it’s all about the tail, which it uses to deadly effect. Its prey know that hungry sharks often separate an individual from the group. So, they seek safety in numbers, packing closely together in a spherical formation known as a bait ball. Unfortunately for them, that’s not much of a defence. The shark swims at full speed into the cluster of fish then uses its pectoral fins to slam on the brakes. At the same time, it whips its tail over its head or crashes it to the side. At over 45 mph, the mega shockwave that surges through the water stuns the fish. The shark can then easily gobble up to seven fish in one mouthful.
• Unborn thresher sharks are cannibals! Unlike most fish, the pups in the womb are not connected to the mother via a placenta but feed on her unfertilised eggs[MA1] .
• At birth, they are almost half the length of their mother at around three to five feet. Researchers believe that the unusually large and free-swimming pups are less vulnerable to attack by other sharks.

Scary facts

• Thresher sharks are an endangered species. They are targeted by fisheries for meat, for shark fin soup, their livers are used for vitamins and cosmetic products and their skins in leather production.
• Sports fishermen sometimes try to catch them by the tail. Even if they release them quickly, this can be fatal because the sharks must keep swimming to pass oxygenated water over their gills.
• Since their habitats are heavily fished, they are often caught as bycatch.
• Only having two pups at a time makes it hard for these sharks to recover from these issues but there are positive signs. In 2017, all three thresher shark species gained protections under the Convention on International Trade in Endangered Species (CITES). CITES is the international treaty which aims to protect threatened animals from the wildlife trade.

How you can help

• Follow organisations such as Greenpeace or the Shark Trust and share your support for conservation measures.

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