A beach day with a difference! Download The Shark Trust App and look for Shark Egg Cases

What are Shark Egg Cases and why look for them?

Some sharks, and all true skates, reproduce by laying eggs. These are surrounded by a tough leathery capsule that protects the embryo as it develops inside. Small slits in the egg case allow fresh oxygenated seawater in, and let waste out, while a yolk sac provides plenty of nutrition. After a period of several months – which varies depending on the species – the eggs are ready to hatch. The top of the egg case will open and a fully formed shark or skate will emerge, where it will have to fend for itself from the moment of birth. Once empty, the egg cases, also known as ‘mermaid’s purses’, often wash up on the beach. 

When can you look for Shark Egg Cases?

Anytime you are on a beach! During picnics, dog walks or sporting activity such as paddle boarding, snorkelling or even diving. Every find counts. You could get involved in an organised event – these are sometimes listed on The Shark Trust website. But the great thing about hunting for egg cases is that it can be done anytime.

If you are on or under the water then underwater records help pinpoint exactly where sharks and skates are laying their eggs and can help link to beach records. Learning the depth and substrate that they lay on also helps better understand the species.

The egg cases of different species vary, but the Shark Trust has created some downloadable resources and guides to help you identify which species the egg case belongs to. They are available in English, Welsh, Portuguese, Spanish, Turkish and Dutch so far.

Once you have identified the egg case, you can record your findings on the Shark Trust’s Recording Hub.  But don’t worry – if you can’t identify it, then you can still upload your photo of your find and The Shark Trust do the work for you!

Go Shark Egg Case Hunting!

An Eggcase Hunt makes for a fantastic family day out at the beach, so get involved with shark conservation and have fun too!   Here are some tips to help keep you and the wildlife safe.

Here are some tips to help you look for and identify shark egg cases

Egg cases blend in really well which means they can be difficult to spot at first, so keep your eyes peeled
When egg cases dry out they’re very light and can get blown to the back of the beach. They also get trapped in grasses on sand dunes. So these are good locations to search.
Egg cases will wash up throughout the year. They may have freshly hatched, or been on the seabed for some time before being dislodged.
After stormy weather has passed is prime egg case hunting time. Lots of seaweed and debris will have been washed up on the beach – this is great to search in.
Check to make sure it’s definitely an empty egg case and nothing is inside.
If a live embryo is inside, pop the egg case back in the sea and try to weigh it down so it doesn’t wash ashore again.
Empty egg cases have no secondary purpose as some shells do for hermit crabs. They also don’t break down to form sand.
It’s useful to carry a ruler when egg case hunting so that you can measure the size of the case (do not include the horns when measuring). Measuring will help you identify the species more easily. If you don’t have a ruler to hand photograph your find next to something that is obvious in size e.g. your hand. This will help to verify your egg case.

Eggcase Hunting Safety Tips

Check tide times
Tell someone where you’re going
If possible, use a stick to rummage in seaweed to avoid any nasty surprises
Take care near the base of cliffs
Respect wildlife and habitats by following the Seashore Code and don’t take live animals home with you
Why not do a spot of beach cleaning while you’re there? It goes hand in hand with egg case hunting!

Want to preserve your egg case to show to friends and encourage others?

The Shark Trust recommend preparing your eggcase(s) by doing a bit of bucket science. Rehydrating eggcases makes them much easier to identify. You’ll also see how much they expand to their true size, and how tough they are to protect the developing embryo!

Fill a container with fresh water – you can use anything from a freezer bag to a bucket.

Put the eggcase in the water – if possible try to remove all the air so it sinks.

Leave to soak for 1-2 hours – the longer it’s been out of water, the longer it’ll need to fully rehydrate. Larger eggcases will need to soak for around 24 hours before they return to their original shape. Remove the eggcase from the water

Get cracking with identifying your find! Once you’ve identified and photographed your eggcase you can dry them out in a well-ventilated spot. As long as they’re empty, they shouldn’t smell.

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