Frequent Questions

Girl with Eggcase © Rachel Coppock.Glossary:
Central capsule within the eggcase, within which the embryo develops.
Capsule size: Given by length and width ranges based on data submitted to the Shark Trust. Capsule length includes both fields but excludes the horns. Capsule width includes the lateral keels.
Concave: Curves/dips inwards.
Convex: Curves/dips outwards.
Distal: Bottom end of capsule.
Fields: Flattened extensions at either end of the capsule, between the horns.
Filamentous: Strap-like, like shoe-laces
Keels: Flattened extensions running along either side of the capsule.
Longitudinal: Along the length of the structure.
Oviparous: A mode of reproduction in which females deposit eggs on the sea bed, which hatch in less than a month to more than a year, producing juveniles which are miniatures of the adults.
Ovoviviparous: Live bearing in which the young are nourished primarily by the yolk in the yolk-sac, which is gradually depleted and the yolk-sac resorbed until the young are ready to be born.
Proximal: Top end of capsule where juvenile exits.
Viviparous: A reproductive mode where the maternal adult gives birth to live young.

➤   What is an eggcase?

An eggcase, which is also known as a mermaid’s purse, is a tough leathery case that protects the embryo of a shark, skate or ray as it develops on the sea bed. Each eggcase contains one embryo which will develop over several months into a miniature shark.

➤   I need some help identifying my eggcase? 

➤ Check out our Eggcase ID Troubleshooter.

➤ Download the Eggcase ID Guide (pdf).

➤ Download the Eggcase ID Key (pdf).

Or email us a photo of your eggcase, if possible against a scale (ruler/2p coin), so we can help you identify the species.

➤   Where, on the beach, am I most likely to find eggcases?

Once eggcases dry out, they’re light and often get blown to the back of the beach. They can often be found in the grass on sand dunes, along the beach edge walls and enclaves sheltered from the wind.

➤   I have searched my local beach and never found an eggcase. Why is this?

There are a number of reasons for not finding eggcases:

  • Although eggcases do wash up year round, they more commonly do so after stormy weather. It may be that you are searching after a period of calm weather.
  • Many beaches, especially tourist beaches, are routinely cleaned and so any extraneous material on the shore is cleared resulting in expanses of beaches absent of everything except sand.
  • The North Sea has seen a dramatic decline in skate and ray catches by fishing fleets over recent years. The populations of these animals in this area are therefore almost non-existent. Consequently, eggcase hunting on the North and East of the UK has demonstrated this fact – numerous hunts have been conducted but no eggcases have been found.

➤   I want to go looking for eggcases, do you have any tips or advice?

For some helpful tips and advice about eggcase hunting visit our Eggcase Hunting  page.