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Creature Feature: Swell Sharks

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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.

This month we’re taking a look at some truly swell sharks, the Swell Sharks!

Swell Sharks are a group of catsharks belonging to the family Scyliorhinidae. Their most unique feature is probably their threat response: they are able to expand their bodies to twice their normal size by swallowing water! This wedges them into their hiding spot, making it more difficult for predators to bite them from inside.

There are 18 different species of swell shark. In this article, we will focus on two of them, the Swell Shark (Cephaloscyllium ventriosum) and the Australian Swell Shark (Cephaloscyllium laticeps).

The Swell Shark (Cephaloscyllium ventriosum)

Biofluorescence

In 2019, scientists discovered the molecules responsible for a special ability of the swell shark – their biofluorescence. In the dark, special amino acids in their skin reflect the moonlight, appearing bright green in the darkness. This has been found to be species specific, and sex specific, and therefore this unique adaptation may function to help sharks species recognise each other or even potential mates. It may also play a role in camouflage.

Australian Swellshark, Cephaloscyllium laticeps

The Australian Swellshark is also sometimes known as the Draughtboard Shark due to its colouration: It has 11 brown ‘saddles’ that alternate with blotches on its flanks, forming a pattern resembling that of a checkerboard.

Oviparity

Like many other species of Swell Shark, the Australian Swellshark is oviparous. This means that the adult swell shark lays an eggcase with the embryo inside. Depending on the species, the shark may lay two at a time. These eggcases contain a developing embryo and a yolk. Before hatching, the embryo can feed on this yolk for sustenance as it grows. Once fully developed, the embryo hatches out as a fully formed miniature version of the adult shark.

Australian Swell Sharks have a particularly interesting eggcase: cream-coloured and flask shaped, this eggcase has 19-27 transverse ridges (lined horizontally across the eggcase). As with most catsharks, there are long curly tendrils on either end too.

Status

Although the Swell Shark is listed as Least Concern globally on the IUCN Red List of Threatened Species, some species of are listed as Critically Endangered. Take, for instance, the Whitefin Swellshark, endemic to southeastern Australia. Much of its habitat overlaps with areas of intensive fishing effort – as such, although not a target species, they were and still are frequently caught as bycatch. According to the IUCN, populations have reduced by >80% over the past three generations,

Scientific Name: Cephaloscyllium ventriosum

Family: Scyliorhinidae

Maximum Size: 110cm

DietSmall crustaceans, cephalopods and fish

Distribution: Eastern Pacific, most commonly found at 5m to 40m depth.

Habitat: Usually found in rocky areas of kelp beds.

Conservation Status: They’re not typically targeted for food as their meat is generally considered to be of poor quality. They are however, often caught as bycatch in gillnets and trawls.

IUCN Red List Status: Least Concern

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


Image Credits:

biofluorescence (Sparks, J. S.; Schelly, R. C.; Smith, W. L.; Davis, M. P.; Tchernov, D.; Pieribone, V. A.; Gruber, D. F., CC BY 4.0 <https://creativecommons.org/licenses/by/4.0>, via Wikimedia Commons)

laticeps (Mark Norman / Museum Victoria, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons)

Eggcase 1 ‘Cephaolscyllium ventriosum’ (vagabondvince310, CC BY 2.0 <https://creativecommons.org/licenses/by/2.0>, via Wikimedia Commons)

Eggcase 2 ‘Cephaloscyllium laticeps eggcase’ (Museum Victoria, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons)

Nick and Caroline (Frogfish Photography) are a married couple of conservation driven underwater photo-journalists and authors. Both have honours degrees from Manchester University, in Environmental Biology and Biology respectively, with Nick being a Fellow of the Royal Photographic Society, a former high school science teacher with a DipEd in Teaching Studies. Caroline has an MSc in Animal Behaviour specializing in Caribbean Ecology. They are multiple award-winning photographers and along with 4 published books, feature regularly in the diving, wildlife and international press They are the Underwater Photography and Deputy Editors at Scubaverse and Dive Travel Adventures. Winners of the Caribbean Tourism Organization Photo-journalist of the Year for a feature on Shark Diving in The Bahamas, and they have been placed in every year they have entered. Nick and Caroline regularly use their free time to visit schools, both in the UK and on their travels, to discuss the important issues of marine conservation, sharks and plastic pollution. They are ambassadors for Sharks4Kids and founders of SeaStraw. They are Dive Ambassadors for The Islands of The Bahamas and are supported by Mares, Paralenz, Nauticam and Olympus. To find out more visit www.frogfishphotography.com

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Saba’s Plan for a Coral Comeback

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Saba

Saba has an exciting new initiative to restore its coral reefs. This new project, running from 2024 to 2026, will focus on reviving key species in the island’s underwater ecosystems. With a collaborative team from the Saba Conservation Foundation (SCF) and Van Hall Larenstein (VHL) University of Applied Sciences, the project aims to restore both corals as well as sea urchins.

This initiative is centered around coral restoration, specifically reviving two essential coral species—staghorn coral (Acropora cervicornis) and elkhorn coral (Acropora palmata).  By mapping parent colonies and using a technique known as coral gardening, SCF will create and maintain coral nurseries. These corals will eventually be outplanted at key reef sites around Saba to not only expand the number of coral colonies, but also provide essential fish habitat. The project focusses on installing coral nurseries, training staff with the newest techniques and starting with the restoration of key reef sites.

Saba

Reef Cleaners to the Rescue

It’s not just corals getting a makeover—this project also shines a spotlight on the essential role of grazers, particularly sea urchins. VHL is leading the charge on cultivating and restocking two key sea urchin species, West Indian sea egg (Tripneustes) and long-spined sea urchin (Diadema), known for their ability to keep algae in check. By removing algae, which are important competitors of corals, they help the coral to thrive. By restoring these “reef cleaners,” Saba’s project will give corals the breathing room they need to grow, setting the stage for a healthier, more balanced marine ecosystem.

From Tiny Urchins to Big Goals

The project will be funded as part of the Dutch Government’s Nature and Environment Policy Plan (NEPP) 2020-2030 for the Caribbean Netherlands, a comprehensive initiative aimed at conserving and restoring the unique natural environments of the Dutch Caribbean islands, including Saba, St. Eustatius, and Bonaire. This project is aiming for big milestones:  build and maintaining coral nurseries, the expansion of urchin cultivation facilities, and the creation of a dedicated research center. By 2026, the project hopes to ramp up coral and grazer restoration, with the ultimate goal of extending these efforts across the Dutch Caribbean. By linking local initiatives to broader regional goals, Saba’s restoration project promises to leave a lasting impact on both the environment and the community.

Find out more about the DCNA at dcnanature.org.

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Reef-World marks two decades of marine conservation: strengthening impact amid coral reef threats

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reef world foundation

Empowering ocean stakeholders to tackle future challenges and ensure the survival of coral reefs and humanity

2024 marks the 20th Anniversary of The Reef-World Foundation’s tireless efforts for global coral reef conservation. The UK charity is the international coordinator of the UN Environment Programme’s Green Fins initiative, known as the leading voice in sustainable marine tourism. Today, Reef-World released its 2023-2024 Impact Report outlining a year of substantive growth and impact in its marine conservation programmes. 

Impact Report Highlights:

  • Impressive improvements in environmental behaviours to protect coral reefs by the marine tourism industry as the global participation of Green Fins increases.
  • Continued capacity building for government and NGO staff to effectively manage marine tourism activities in Asia, Caribbean and Red Sea regions. 
  • For the first time in Green Fins’ 20-year history, tourism operators have achieved ‘Best Environmental Performer’ status by demonstrating the lowest possible environmental impact in their environmental assessments. In 2024, three dive operators achieved this challenging milestone. 
  • Significant increases in global participation of Reef-World’s innovative digital conservation tools.
  • 138 Green Fins dive operator members achieved the strict threshold for PADI Eco Center recognition.
  • Developed four new educational materials and translated two into 16 languages to support the marine tourism industry in achieving sustainability targets.
  • Establishing a new Reef-World Development strategy and recruiting new roles – Development and Programmes Managers. 
  • Reef-World’s board welcomes new Chair and Trustees strengthening organisational leadership. 

Reef-World started as a one-person mission to inspire and empower communities to act in conserving and sustainably developing coral reefs and related ecosystems. Today, the team of 12 continues to meet this mission by inspiring and empowering the global marine tourism community to be exemplary sustainability leaders by using the Green Fins guidelines and tools to simultaneously use and protect the world’s precious reefs. 

In April 2024, the fourth global coral reef bleaching event was confirmed. Reef-World’s work has never been more urgent as the marine environment, and the benefits they provide humanity, continue to be eroded by global threats. The reduction of local threats, like those from the marine tourism industry, is an essential step to ensuring a future where coral reefs survive and continue to support the millions of people who depend on their ecosystem benefits. Reef-World’s work buys time for coral reefs and related ecosystems to be resilient to the impacts of global threats. 

 

“Right now our corals are facing the greatest fight of their existence as the terrifying predictions of the steps towards their complete extinction are starting to come true. But all is not lost, reefs are resilient and they have existed on this planet for millions of years. We must take action now, to buy time for reefs by reducing threats facing them and allowing them to react and adjust to the changing environment they need to survive in.” – Chloe Harvey, Executive Director

Looking Forwards: 

Like coral reefs, the Reef-World team needs to be resilient in the face of the complex challenges of the conservation sector. Reef-World has invested significantly in developing a Culture of Care to ensure the well-being of its team on a daily basis, continuing to be an exemplary employer to enable its team to best achieve the mission for coral reef conservation.

With the foundations of a Culture of Care and organisational development laid, Reef-World is emerging from the end of a natural organisation life cycle, that brings the challenges of growth and scale, stronger than ever. With a new strategy in place to generate much needed resources, Reef-World is excited for the opportunities to leap forward, continue to scale our impact and lean into new innovations and untapped opportunities for marine conservation. 

We continually strive to become a forward-thinking organisation that delivers on our goals and commitments to our stakeholders with fresh approaches and not being afraid of steering away from a “normal approach.” This approach is not only applied to our programmes of work but also internally and carries over to our Culture of Care for our team.” — JJ Harvey, Operations Director

reef world foundation

The Reef-World Foundation is immensely grateful for the continued support of its grant funders: UN Environment Programme, IUCN’s Blue Natural Capital Financing Facility, Adventure Travel Conservation Fund, PADI Aware Foundation, and World Nomads Footprints Program.

Reef-World would also like to express its gratitude to international partners whose vital support has resulted in significant tangible benefits for our work and mission: PADI; Professional SCUBA Schools International (PSS); Explorer Ventures; 1% for the Planet; ZuBlu; Snorkel Venture, GSTC; Dive O’Clock; Seven Dragons; DiveAssure and Eco Beach, without whom these achievements would not be possible.

The full 2023–2024 Annual Impact Report is available on Reef-World’s website.

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