Marine Life & Conservation Blogs
Book Review: Shells of the World
Shells of the World: A Natural History by M.G. Harasewych
Shells of the world is a guide to the world of marine, shelled molluscs. And what a varied and interesting world it is. Some of my favourite things to find on a dive are detailed in this book, including disco clams (or Electric File Clams as they are correctly names), the cephalopods, giant clams and sea hares. There are also many on my wish list, top of which is the Nautilus.
Each chapter provides a detailed description of the species, along with beautiful images. You can dive deeper and discover where they live, both with global distribution and the habitat they prefer. Learn about their diet, reproduction and diversity.
Having dipped in and out of this lovely book over the past few weeks, it has inspired me to learn more about this group of animals that we see on most divers, wherever we are in the world. Some of the shells are incredibly intricate and beautiful. I have always agreed with never collecting, or touching, marine life. The description of a certain set of cone shells should be a warning to those that are happy to pick up marine life! One of the cone shells has a local name called the cigarette snail. Why? Because once the venom is in your system from this animal, you only have time to smoke one cigarette before the affects of the venom are fatal!
What the publisher says:
Mollusks are invertebrate animals with a remarkable natural history and a rich fossil record, and their shells are prized for their breathtaking variety and exquisite beauty. Shells of the World provides a wide-ranging look at the incredible diversity of marine mollusks. An informative introduction outlines the lineages covered, followed by a directory section, split into classes, that profiles a broad selection of different taxa to give a sense of their sheer numbers and variety.
- Features hundreds of beautiful color photos, depicting both the live animals and their shells
- Discusses mollusk evolution, anatomy, life cycles, behavior, and ecology
- Describes unique characteristics, distribution, habitat, and size
- Provides valuable insights into the conservation of the world’s marine mollusks
- Ideal for malacologists and shell collectors everywhere
About the Author:
M. G. Harasewych is research zoologist emeritus and former curator in the Department of Invertebrate Zoology at the Smithsonian Institution’s National Museum of Natural History. A fellow of the American Association for the Advancement of Science, he is the author (with Fabio Moretzsohn) of The Book of Shells: A Life-Size Guide to Identifying and Classifying Six Hundred Seashells.
Book Details
Publisher: Princeton University Press
Hardcover
Price: £25
ISBN: 9780691248271
Published: 9th April, 2024
Marine Life & Conservation Blogs
Creature Feature: Butterfly Rays
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.
As we’re currently in butterfly season, this month we decided to concentrate on the Butterfly Rays!
Within the family Gymnuridae, there are two genera and 12 species of Butterfly Ray. These species are morphologically different to lots of other rays because of the width of the disc and pectoral fins – in contrast to many other species of Butterfly Ray, their bodies are much wider than they are long, especially considering their very short tail. This gives them the appearance of gliding or flying across the sand.
Gymnura altavela – Spiny Butterfly Ray
Gymnura australis – Australian Butterfly Ray
Gymnura crebripunctata – Longsnout Butterfly Ray
Gymnura japonica – Japanese Butterfly Ray
Gymnura lessae – Lessa’s Butterfly Ray
Gymnura marmorata – California Butterfly Ray
Gymnura micrura – Smooth Butterfly Ray
Gymnura natalensis – Backwater Butterfly Ray
Gymnura peocilura – Longtail Butterfly Ray
Gymnura sereti – Seret’s Butterfly Ray
Gymnura tentaculata – Tentacled Butterfly Ray
Gymnura zonura – Zonetail Butterfly Ray
Today we’re taking a look at Gymnura altavela, the Spiny Butterfly Ray. Like all Butterfly Rays, the Spiny Butterfly Ray is a demersal species, meaning it spends the majority of its time on the bottom of the seabed. Butterfly Rays are known for their burying behaviour in the sand, a technique they use to camouflage themselves when they are resting during the day. This protects them from predators, in some areas larger sharks. It also aids them in their ambush hunting technique – by hiding themselves under the sand they are able to easily snatch up their dinner – usually crustaceans, molluscs or other small fish – as they swim by unawares. This behaviour can leave tell-tale butterfly-ray shaped imprints in the bottom of the seabed.
Spiny Butterfly Rays can grow up to 260 cm (disc width (wingspan)), although average is around 200 cm. They give birth to live young, and each litter consists of 1-8 pups. This species has also been found to aggregate, likely for mating. One study found that aggregations of primarily females in the coastal regions off Gran Canaria may correlate with the shifting water temperature.
It is estimated that the species has undergone a population reduction of 50-79% over the last 33 years. This is primarily due to fishing pressure – the Spiny Butterfly Ray is targeted and bycaught in both industrial and artisanal fisheries types using a variety of gear types. The species is now Critically Endangered in the Mediterranean and Southwest Atlantic.
Scientific Name: Gymnura altavela
Family: Gymnuridae
Maximum Size: 260 cm (disc width)
Diet: crabs, shrimps, various invertebrates, fishes, small crustaceans, and molluscs.
Distribution: throughout the Atlantic and Mediterranean and Black Seas.
Habitat: muddy and sandy substrates down to 150m.
Conservation status: Critically Endangered in the Mediterranean and Europe, Endangered Globally.
For more great shark information and conservation visit the Shark Trust Website
Banner Image: ©Tomas Willems. Main image: ©Andy Murch
Blogs
Seal Encounter Dives at Lundy Island
Voted No. 3 on the Top 10 Ultimate British Isles Bucket List by The Independent, these dives offer the closest marine mammal encounter available to divers in the UK. Friendly and playful, respectful divers are often rewarded by incredible interaction with the Lundy Seals.
Easy Divers has been running guided dive trips to Lundy for nearly 10 years and offers dive equipment hire if required. Trips depart from the stunning harbour town of Ilfracombe in North Devon and Dolphins are often seen during the boat passage.
In addition to diving, Ilfracombe is a great base from which to hike the South West Coast Path, dip into surfing at the UK’s first World Surf reserve, enjoy other water sports or head to Exmoor National Park.
Easy Divers also runs a diver-friendly guest house, with a discount for diving customers and kit rinsing and drying facilities.
The Seal encounter dive sites are shallow and sheltered and are suitable for divers of all levels, making them a great introduction to British diving.
Exclusive Offer for Scubaverse Subscribers
Use your exclusive Scubaverse discount code scubaverse10% before the end of June and join us for a Seal encounter dive trip to Lundy Island, on any trip date with availability this Summer. Visit https://www.easydiversnorthdevon.co.uk/lundy-dive-trips/seal-encounter-dive-trips/ and enter code scubaverse10% at the on-line check out.
Trips book out well ahead, so book now to avoid disappointment. To save 10% on any 1 night stay at our guest house, please call 07833 020424. We offer free cancellation for divers who book a 1 night stay, if we have to re-schedule due to unsafe weather.
Join us for Britain’s best marine mammal diving experience!
Trips run from end of May to mid-October and are bookable via email at info@easydiversnorthdevon.co.uk, on-line via the Easy Divers website, www.easydiversnorthdevon.co.uk, or call 07833 020424 for more info
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