The strandline is the line of debris left on the beach when the tide falls, it is easy to dismiss it as a heap of rotting seaweed, in some places it is mechanically cleared away to prevent smell and visual nuisance.

Looking closer we start to realise that there is more to the strandline than meets the eye – small creatures live amongst it, human litter is mixed up with natural debris, and most surprisingly of all we find evidence of sharks in our waters.

Many species of sharks and their relatives the skates and rays lay eggs on the seabed. Within each egg a tiny fish grows for several months before finally biting its way out and swimming away.

The empty eggcases that are left behind often get washed up on beaches, especially after a big storm which may tear the seaweed they are attached to from the seabed.

The eggcases or ‘mermaids’ purses’ as they are known are brown or black and look very much like seaweed to which they may still be attached by tightly curled tendrils.

As they dry out on the beach they become brittle and hard but each small capsule retains a distinctive shape. Scientists have learned, through studying sharks and rays in aquaria, to determine how to identify which eggcase belongs to which species.

Anyone can look for eggcases and the ideal time to do it is during the autumn and winter especially after a period of rough weather.

Hampshire and Isle of Wight Wildlife Trust include eggcase hunting in their marine conservation programme because it helps to build up knowledge of the marine life in our waters.

In fact the area to the east of the Isle of Wight is known to be particularly rich in skates and rays.

Our latest eggcase hunt took place during European Shark Week in October and was held at Hayling Island. We found 21 eggcases belonging to 3 different species of sharks and rays and helped to raise awareness of the need for their conservation.

One participant, a Hayling Island resident said ‘this is great, I had no idea the eggcases were here, I won’t look at the strandline in the same way again now’.

The results of the survey go to the Shark Trust which holds a national database of eggcases and sightings of sharks and rays in our waters.

Their expert knowledge helped us to confirm the identity of some of the trickier eggcases to recognise.

Eggcases are only one part of the picture; we also record any sightings of sharks and rays that we hear about.

One of the best sources of information is anglers, who may have photographs of the beautiful skates and rays that they catch which are often later released unharmed. Divers too sometimes see thornback rays, lesser spotted catsharks and their relatives underwater.

Occasionally they even see the eggcases underwater, still with a baby fish inside them, sometimes it is even possible to see an eye looking out.

Sharks are globally threatened by overfishing and many skates and ray species also suffer in this way. The Common Skate, like many others, is very slow to reproduce; it lays only about 40 eggs every other year and takes eleven years to mature.

As its name suggests, it was once occurred frequently in fishing trawls but it is now thought to be extinct in the North Sea.

Learning more about these fish can help to conserve them and their important areas such as nursery grounds.

Eggcase hunting is great fun and quite addictive! You don’t need any special equipment, and you can do it whenever you like.

If you’d like some hints on getting started you can contact Hampshire and Isle of Wight Wildlife Trust on 01489 774400, feedback@hwt.org.uk and our website hwt.org.uk.