Description
This dataset details approved records from the Shark Trust's Great Eggcase Hunt, active since 2003. Comprised of citizen science observations, both on land and in-situ, records of eggcases from around the world have been complied to help better understand these oviparous species. Data comes from ad-hoc records, regular surveys and data uploads from partner organisations. Please note that not all records are verified, but this has been indicated in the extended Measurements or Facts.
Data Records
The data in this sampling event resource has been published as a Darwin Core Archive (DwC-A), which is a standardized format for sharing biodiversity data as a set of one or more data tables. The core data table contains 38,092 records.
2 extension data tables also exist. An extension record supplies extra information about a core record. The number of records in each extension data table is illustrated below.
This IPT archives the data and thus serves as the data repository. The data and resource metadata are available for download in the downloads section. The versions table lists other versions of the resource that have been made publicly available and allows tracking changes made to the resource over time.
Versions
The table below shows only published versions of the resource that are publicly accessible.
How to cite
Researchers should cite this work as follows:
Allen H, Gordon C (2026). Great Eggcase Hunt - global citizen science observations of chondrichthyian eggcases. Version 1.2. Shark Trust. Samplingevent dataset. https://www.dassh.ac.uk/ipt/resource?r=st_greateggcasehunt&v=1.2
Rights
Researchers should respect the following rights statement:
The publisher and rights holder of this work is Shark Trust. This work is licensed under a Creative Commons Attribution (CC-BY 4.0) License.
GBIF Registration
This resource has been registered with GBIF, and assigned the following GBIF UUID: 3410af95-8fc6-4122-876d-d2ce503910ca. Shark Trust publishes this resource, and is itself registered in GBIF as a data publisher endorsed by Ocean Biodiversity Information System.
Keywords
Samplingevent; oviparity; Egg; social participation; Chondrichthyes; Observation
Contacts
- Metadata Provider ●
- Originator ●
- Point Of Contact
- Data Analyst
- 4 Creykes Court, 5 Craigie Drive
https://orcid.org/0000-0001-5108-2032
- Originator ●
- Point Of Contact
- Senior Conservation Officer
Geographic Coverage
Global, with a participation bias from the British Isles.
| Bounding Coordinates | South West [-90, -180], North East [90, 180] |
|---|
Taxonomic Coverage
Chondrichthyes, specifically Heterodontidae, Orectolobidae, Rajidae, Scyliorhinidae and Chimaeriformes
| Class | Chondrichthyes |
|---|---|
| Order | Chimaeriformes (chimaeras) |
| Family | Heterodontidae (bullhead sharks), Orectolobidae (carpet shark), Rajidae (skate), Scyliorhinidae (catsharks) |
Temporal Coverage
| Start Date / End Date | 2003-01-01 / 2024-12-31 |
|---|
Project Data
The Shark Trust’s Great Eggcase Hunt engages communities in searching for, identifying, and recording the eggcases of sharks, skates and chimaera. This feeds a better understanding of these species, and which areas provide important habitats like egglaying grounds. Some citizen scientists regularly submit finds from their local beaches, while others may make a new shoreline discovery that leads them to discover what a mermaid’s purse really is. With over half a million eggcases recorded by the public over 20+ years, this dataset displays the broad distribution, diversity of species, and relative abundance of sharks, skates and chimaera around the British Isles and further afield. This data allows for an improved understanding of this important development stage of a sharks or skates life-cycle.
| Title | Great Eggcase Hunt - global citizen science observations of chondrichthyian eggcases, 2003-present. |
|---|---|
| Identifier | ST_GEH |
| Funding | Historic funders include: Co-op, Countryside Council for Wales, Crown Estates, DTO Bio-Flow, Esmée Fairbairn Foundation, Museums and Galleries of Wales, National Lottery Heritage Fund, Natural England, Save Our Seas Foundation, Scottish Natural Heritage, Sea Changers and donations received through specific Shark Trust appeals. |
| Study Area Description | Global, with a participation bias from the British Isles. |
| Design Description | Eggcases can be recorded from anywhere around the world, whether recorded in-situ, or washed ashore on the beach, in the sand dunes or the car-park. Records are submitted on an ad-hoc basis, with some Eggcase Champions and partner organisations undertaking more regular, structured surveys. |
The personnel involved in the project:
- Owner
Sampling Methods
Records are gathered from citizen science observations submitted on an ad-hoc basis, with some Eggcase Champions and partner organisations undertaking more regular, structured surveys.
| Study Extent | Data is generated from citizen science observations. Many are ad-hoc finds, while some areas are more regularly surveyed using a standardised methodology. The majority of finds are from beach records, with some being in situ records observed while snorkelling or diving. |
|---|---|
| Quality Control | All data has been approved by a member of staff or via a user of the Community Verification Platform before publication. All records have undergone internal Quality Checks, with checks made against known species range and pin location checked and adjusted as required. |
Method step description:
- NA
Additional Metadata
| Acknowledgements | This dataset would not be possible without the contributions of all citizen scientists and organisations that have participated. Whether reporting one ad-hoc find or thousands of records over the span of years, every record has helped build towards this combined dataset. Data transformation and publication was funded by the European Union under the Horizon Europe Programme with Grant Agreement No. 101112823 (DTO-BioFlow) through an FSTP call. |
|---|---|
| Introduction | The Shark Trust’s Great Eggcase Hunt engages communities in searching for, identifying, and recording the eggcases of sharks, skates and chimaera. This feeds a better understanding of these species, and which areas provide important habitats like egglaying grounds. Some citizen scientists regularly submit finds from their local beaches, while others may make a new shoreline discovery that leads them to discover what a mermaid’s purse really is. With over half a million eggcases recorded by the public over 20+ years, this dataset displays the broad distribution, diversity of species, and relative abundance of sharks, skates and chimaera around the British Isles and further afield. This data allows for an improved understanding of this important development stage of a sharks or skates life-cycle. |
| Getting Started | This data is comprised of three tables: Event, Occurrence and extended measurements or facts. The field 'search effort' details the number of participants taking part in the survey as a measure of effort. However, this field has only been in use since 2022. The field 'locationRemarks' details whether the eggcase was seen developing in-situ underwater, or it was recorded on-shore - likely a spent eggcase. While every record is checked by a member of staff or through the Community Verification Platform, 'identificationVerificationStatus' flags whether the record had any evidence to prove the species ID. Accepted evidence types include a photograph, specimen or expert ID. |
| Purpose | This dataset displays the broad distribution, diversity of species, and relative abundance of sharks, skates and chimaera around the British Isles and further afield. |
| Maintenance Description | Each subsequent year of data will be uploaded once internal QC has been completed. |
| Alternative Identifiers | https://www.dassh.ac.uk/ipt/resource?r=st_greateggcasehunt |