Mermaid's Purse

Mermaid's Purse

Do you own a pair of wellies and love going to the beach? If you enjoy rummaging through the strandline the chances are that you’ve seen many of these fascinating things known as mermaid’s purse.

What is a Mermaid’s Purse?

Mermaid’s Purse is the popular name for the egg cases of elasmobranchs – the collective name for sharks, skates and rays. A number of different species of skates, rays, small sharks, catfish and dogfish lay their eggs underwater in these egg cases.

The egg case is made from Keratin – that’s the same material which our fingernails are made from. The little tendrils on the corners help to hold the case in a safe, sheltered place in the sea. Perhaps in a bed of seaweed or a crevice.

When they are first laid, the egg cases are waterproof because the little embryonic fish don’t have gills until they are 3 weeks old.

Mermaid's Purse with a little fish inside
Mermaid’s Purse with a little fish inside

Once the little embryonic fish has developed its gills after 3 weeks, small holes open in the tips of the horns to let seawater in. The baby fish learns to live as an underwater animal. The Mermaid’s Purse protects it for up to 12 months as it incubates.

When the tiny fish is fully formed, hatched and swum away, the empty egg case, or Mermaid’s Purse, often get washed up on our shores.

The smaller, more transparent egg cases with the corkscrew tendrils like the ones in the photo below are the cases of dogfish. The larger, blacker and harder ones are the cases of rays and skates.

Mermaid's Purse, the egg cases of dog and catfish
Mermaid’s Purse, the egg cases of dog and catfish

Identifying Mermaid’s Purse

Worldwide, there are more than 600 species of skate and ray, at least 16 of which are regularly found on UK shores.

Did you know that there are over 30 species of British sharks, but only two of them lay egg cases which you’ll find on a UK beach. They are the Small Spotted Catshark and the Nursehound.

Unfortunately, in recent decades, numbers of these fish have declined dramatically in our waters. Identifying and counting washed-up Mermaid’s Purse is a great way to record and track them. They help us to understand where their nursery beds are, and how their populations are faring.

Dogfish corpse, washed up on the beach. This is a small type of shark, which started life in a Mermaid's Purse
Dogfish corpse, washed up on the beach. This is a small type of shark, which started life in a Mermaid’s Purse

Collect Mermaid’s Purse for the Great Eggcase Hunt

In recent decades several species of skate and ray around the British coastline have dramatically declined in numbers.

The Shark Trust need your help to identify and register these finds, on the beaches of the Fylde Coast from Fleetwood to Lytham.

By identifying where these fish live, the Shark Trust can propose conservation measures in order to reverse the decline of these charismatic animals.

Does identifying and recording egg cases sound like something you’d like to have a go at?

The Great Eggcase Hunt is one of the UK’s most popular marine volunteer recording programmes. Established in 2003 it engages people in hunting for eggcases (otherwise known as mermaid’s purses) along the coastline.

Reported findings allow the Shark Trust to identify potential nursery grounds, which in turn, provides valuable data that aids conservation and helps with the management of UK shark, skate and ray populations.

Download and save the next image and use it to identify your finds. There are LOTS of resources on the Eggcase Hunt Project website.

Identifying Mermaid's Purse - the eggcase of skates, rays and sharks
Identifying Mermaid’s Purse – the eggcase of skates, rays and sharks

Head for the beach, collect all the egg cases you see, and when you come back report your findings at the same link.

Why the name ‘Mermaid’s Purse’?

Here at Visit Fylde Coast we think we know why these clever little pods have the lovely name ‘Mermaid’s Purse’.

We assume that it’s because they look like a purse, come out of the sea, so therefore it’s reasonable to assume they’ve been lost by mermaids.

Do you know anything different? Have you ever heard any folklore about how they got their name? If so, please leave a comment below. We’d love to know!

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