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The Shark Trust: Great Eggcase Hunt

Main Project Information
Presented By The Shark Trust
Goal To improve knowledge of egglaying shark & skate distribution.
Task Hunt for empty eggcases washed up on the beach, or found in-situ
Where Global, anywhere on the planet

The Great Eggcase Hunt is a Shark Trust citizen science recording project, which encourages people to get out on the beach and look for mermaid's purses (the eggcases of sharks, skates and rays) and then record what they find!

An eggcase (or mermaid’s purse) is a tough leathery case that protects the embryo while developing. Each eggcase contains one embryo which will develop over several months into a miniature version of the adult. There are over ten species of skate and ray, and only a few species of shark in UK waters that reproduce by laying eggcases. Eggcases varies in shape, size and features - these differences allow us to identify which species they came from. Once the juvenile has emerged, the much lighter empty eggcases can wash ashore be found amongst the seaweed in the strandline. We’re also keen to hear about eggcases that are seen in-situ while snorkelling or diving!

In recent decades, several species of shark, skate and ray around the British coast have dramatically declined in numbers. The empty eggcases are an easily accessible source of information on the whereabouts of potential nursery grounds and will provide the Trust with a better understanding of species abundance and distribution.

Thanks to public recording, the Trust now has an extensive database of eggcase records, which continues to provide crucial information about the distribution of British sharks, skates and rays (elasmobranchs).

The Shark Trust is building upon the existing project, which represents one of the UK’s most popular marine volunteer recording programs, and encouraging more international records. The Trust is currently collaborating with the Wildlife Conservation Society (WCS) to establish the project in the USA, and will be developing identification resources for species found along the New York coastline.

The Great Eggcase Hunt ID guide is now also available at your fingertips as a smartphone app has been launched for Apple devices and is available in the app store now! This dedicated app offers tips on how to hunt, an encyclopedia of British egglaying sharks, skates and rays, full ID guide entries, a step-by-step identification tool, and a recording form with the capacity to upload photos and record the exact GPS location. An Android version is coming soon!

How to Join

Simply visit and read more about the project, then get to your local beach and start hunting!

Once you’ve found some eggcases, soak them in water so that they rehydrate and you can see the features more clearly, then you can use the ID key at to identify what you’ve found and then finally record them (with photos!) at If you're hunting outside of the UK, then send us an email with photos and we will still endeavour to help you identify your find.

You can register for a Shark Trust website account so your contact details are saved for next time you find and record an eggcase!

Social Media
Required Gear

- A stick/boot to poke around in the seaweed so you don't get any nasty surprises.
- A bag/bucket to collect your eggcases.
- Camera/smartphone to photograph.
- Great Eggcase Hunt ID guide to identify your finds.
- Access to the online recording form to let us know what you've found!

Ideal Age Group Elementary school (6 - 10 years), Middle school (11 - 13 years), High school (14 - 17 years), College, Graduate students, Adults, Families
Spend the Time outdoors
Type of Activity At the beach, In oceans, streams, rivers, lakes, While fishing
Class Materials
Media Mentions
and Publications
Tags eggcases, elasmobranchs, mermaids purses, ocean, rays, reproduction, sharks, skates
Project Updated 08/03/2017