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Creature Feature: Broadnose Sevengill Shark

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In this series, the Shark Trust will be sharing amazing facts about different species of sharks and what you can do to help protect them.

Written by guest contributor – Yolanda Evans.

A small glimpse of grey amongst the the vibrant green of the kelp around the temperate coastal waters could be no other then the incredible Broadnose Sevengill shark! Hinted by their common name, these sharks have seven pairs of gill slits – unlike the typical five. These sharks can reach up to 3 metres long and are commonly misidentified as the other species of sevengill the Sharpnose Sevengill. The Broadnose is distinguished by small black and white freckles on their fins and underside and a much larger head then the Sharpnose.

Unlike many other sharks in the Hexanidae family (Cowsharks), this species prefers waters of less then 50 m in depth; sometimes being found in river estuaries where the depth is around 1m! However, Brodnose’s make seasonal migration during the winter to the continental shelves, following their food and sexually mature females.

Broadnose Sevengill’s have a unique tooth shape in their lower jaws: they are shaped like combs which they use to anchor into their prey. This sharks favourite snacks large fish (including other sharks) and crustaceans but they have been videoed eating carrion (dead/decaying bodies), making them scavengers. There are even reports of cannibalism as the older sharks eat the younger to reduce competition. Once they’ve eaten a meal they wont have to eat again for weeks, in fact, in a month they only consume 6% of their body weight!

Predominantly being a solitary shark, they do sometimes congregate in groups to hunt. They mainly do this to get to bigger prey which could be too much work for a single shark. Stalking behind their prey, these sevengill’s will then rapidly burst out to chase down their prey.

Sevengill’ are ovoviviparous and can give birth to 60-180 pups, an incredibly high amount. The pups remain in the shallow waters until they reach a certain size to help avoid predators.

Recent carcasses of these sevengill’s have been found worldwide, all with their livers missing. Who could be behind this series of surgically-precise murders other then the infamous Orca. Orca, or Killer Whales,purposefully seek out Broadnose Sevengill sharks for their livers rich in fats, making a high calorie snack for these mammals. The Orca turn the shark over on their backs, putting them in a state of tonic immobility, and then using their sharp conical teeth they precisely remove the liver leaving the rest of the shark as it doesn’t have the same nutritional value. However, a few videos have emerged of these Orcas then playing with their food, pushing the dead sharks body up and down with their snouts!

Orca’s aren’t the only mammal to purposefully hunt down these sharks as the Broadnose Sevengill’s are also targeted by humans for their meat, skin for leather, and their oil, however, their main threat is being caught as by-catch during industrial fishing. The IUCN lists them as Data Deficient, however, it is expected that they are Near Threatened.

SCIENTIFIC NAME: Notorynchus cepedianus

FAMILY: Hexanchidae

MAXIMUM SIZE: Up to 3.3 meters (10.8 feet) in length

DIET: Feeds on a variety of prey including fish, squid, crustaceans, and even other sharks

DISTRIBUTION: Broadnose Sevengill Sharks have a cosmopolitan distribution, found in coastal and offshore waters in temperate and tropical regions worldwide.

HABITAT: Found in a variety of habitats, including estuaries, bays, and shallow reefs, as well as deeper waters of up to 150 meters (492 feet) in depth.

CONSERVATION STATUS:

While there is little data on population trends, this species is known to be caught as bycatch in some commercial and recreational fisheries, and there is also concern over the impact of habitat loss and degradation on their populations.

For more great shark information and conservation visit the Shark Trust Website


Banner image – Aaron Scheiner | Wikimedia Commons

In-text Image – derekkeats | Wikimedia Commons

In-text Image – Coco | Wikimedia Commons

The Shark Trust is the leading UK-based shark conservation charity. The team works globally to safeguard the future of sharks, and their close cousins, the skates and rays. Engaging with a global network of scientists, policymakers, conservation professionals, businesses and supporters, to further shark conservation. Established in 1997 to provide a voice for UK sharks, the Shark Trust has an ever-growing number of passionate supporters. And together we're creating positive change for sharks around the world. Want to join us and help protect sharks around the world? Click here! www.sharktrust.org

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The Ocean Cleanup to Complete 100th Extraction Live from the Great Pacific Garbage Patch

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the ocean cleanup
  • The Ocean Cleanup marks 100th extraction of plastic pollution from the Pacific Ocean by livestreaming entire cleaning operation from start to finish.
  • Occasion brings together supporters, partners, donors and followers as the project readies its cleanup technology for scale-up.
  • Founder and CEO Boyan Slat to provide insight on the plans ahead.

The Ocean Cleanup is set to reach a milestone of 100 plastic extractions from the Great Pacific Garbage Patch.

Extraction #100, scheduled for 28 or 29 May 2024, will be the first ever to be livestreamed direct from the Pacific Ocean, allowing supporters and partners around the world to see up close how the organization has removed over 385,000 kilograms (nearly 850,000 lbs) of plastic from the GPGP so far – more than double the bare weight of the Statue of Liberty.

the ocean cleanup

The mission of The Ocean Cleanup is to rid the oceans of plastic. To do this, the non-profit project employs a dual strategy: cleaning up legacy floating plastic in the Great Pacific Garbage Patch (the world’s largest accumulation of floating plastic), while stopping the flow of plastic from the world’s most polluting rivers.

The Ocean Cleanup captured its first plastic (the first ‘extraction’) in the GPGP in 2019 with System 001, following years of trials and testing with a variety of concepts. Through System 002 and now the larger and more efficient System 03, the organization has consistently improved and optimized operations, and is now preparing to extract plastic trash from the GPGP for the 100th time.

the ocean cleanup

Extraction #100 will be an interactive broadcast showing the entire extraction procedure live and in detail, with insight provided by representatives from across The Ocean Cleanup and partners contributing to the operations.

This is an important milestone in a key year for The Ocean Cleanup.’ said Boyan Slat, Founder and CEO of The Ocean Cleanup. ‘We’ve come a long way since our first extraction in 2019. During the 2024 season, with System 03, we aim to demonstrate that we are ready to scale up, and with it, confine the Great Pacific Garbage Patch to the history books.

the ocean cleanup

The livestream will be hosted on The Ocean Cleanup’s YouTube channel and via X. Monitor @theoceancleanup for confirmed timings.

www.theoceancleanup.com

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Marine Life & Conservation Blogs

Book Review: Plankton

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Plankton: A Worldwide Guide by Tom Jackson and Jennifer Parker

This is a book that jumps off the shelf at you. The striking front cover demands that you pick it up and delve further, even if you may not have known you wanted to learn more about the most diminutive life in our ocean, plankton!

Small it might be. Much of the imagery in the book has been taken under huge magnification. Revealing stunning beauty and diversity in each scoop of “soup”. There is lots to learn. Initial chapters include interesting facts about the different vertical zones they inhabit, from sunlight to midnight (the darkest and deepest areas). I loved finding out more about the stunning show that divers oft encounter on night dives – bioluminescence.

The black water images are wonderful. So this is a book you can have as a coffee table book to dip in and our of. But, these tiny organisms are also vital to our very survival and that of all the marine life we love. They provide half the oxygen produced on our planet. They are also responsible for regulating the planets climate. And for a shark lover like me – they are food for charismatic sharks and rays like the Basking Shark and Manta Ray, along with a huge number of other species. This book contains great insight into their biology, life cycles, migration, and how the changes in currents and sea temperatures affects them.

This is a book that is both beautiful and packed with information about possibly the most important group of organisms on our planet. Anyone interested in the ocean should have it one their shelves.

What the publisher says:

Plankton are the unsung heroes of planet Earth. Passive drifters through the world’s seas, oceans, and freshwater environments, most are invisible or very small, but some are longer than a whale. They are the global ocean’s foundation food, supporting almost all oceanic life, and they are also vitally important for land-based plants, animals, and other organisms. Plankton provides an incomparable look at these remarkable creatures, opening a window on the elegance and grace of microscopic marine life.

This engaging book reveals the amazing diversity of plankton, how they belong to a wide range of living groups, and how their ecology, lifestyles, and adaptations have evolved to suit an enormous range of conditions. It looks at plankton life cycles, the different ways plankton feed and grow, and the vast range of strategies they use for reproduction. It tracks where, how, and why plankton drift through the water; shares perspectives on migrations and population explosions or “blooms” and why they happen; and discusses the life-sustaining role of plankton in numerous intertwined food webs throughout the world.

Beautifully illustrated, Plankton sheds critical light on how global warming, pollution, diminishing resources, and overexploitation will adversely impact planktonic life, and how these effects will reverberate to every corner of our planet.

About the Authors:

Tom Jackson is a science writer whose many popular books include Strange Animals and Genetics in MinutesJennifer Parker is a zoology and conservation writer and the author of several books. Andrew Hirst is a leading expert on plankton whose research has taken him around the world, from the Antarctic to Greenland and the Great Barrier Reef.

Book Details

Publisher: Princeton University Press

Hardcover

Price: £25

ISBN: 9780691255996

Published: 9th April, 2024

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