Wildlife Watch

Sea, Sand and Seals

In the summer, Watch Club members are invited to visit Hilbre Island, a nature reserve off the Wirral coast. At high tide, Hilbre Island, and its neighbours Little Eye and Middle Eye, are surrounded by seawater as it flows into the Wirral Estuary. At low tide it is possible to walk over the sand to the islands. Groups of Watch Club members walked over to Hilbre to see the seals that live there during the summer months. The walk is two miles long, so it is the perfect opportunity for a scavenger hunt along the way!

Examining scavenger hunt finds

On reaching the island, we took a look at the items collected by everyone during the scavenger hunt. There were many colourful shells, feathers and seaweeds. There were also empty crab skins (called exoskeletons) that had been shed as the crabs grow. These shed skins often look like a dead crab but we learned that if there were holes where the eyes were supposed to be, then it was just an empty skin. However, if the crab had been eaten by a seagull, there would be a big hole in the shell!

Other sea debris found during the hunt included fragile sea potatoes and papery whelk egg cases – these looked like lumpy round sponges.

Next, everyone had a go at rock pool dipping also produced more common, or green, shore crabs plus a hermit crab, some small fish and even shrimps!

Some rock pool inhabitants

Rock pool organisms need to be tough to survive. Summer temperatures can be extremely hot while in winter, rock pools can become extremely cold. Also, when the tide is high, the movement of the waves can make it very difficult for creatures to keep their grip on the rocks – and if they let go, they will be swirled around by the water and bashed against rocks.

Because of this, our rock pools are filled with creatures living in very tough shells – the shells provide them with a home that will protect them if they are bounced against any rocks. Rock pools are also home to animals which can adapt to the harsh conditions by hiding in cracks or using the protection that others have made for themselves – like the hermit crabs that find empty marine snail shells and carefully choose a close-fitting shell of exactly the right size to live in. They often squabble over shells and will spend a great deal of time ‘trying-on’ new homes when they find them!

Next, Watch Club leaders set up a large telescope so that everyone could take a closer look at the seals. Over 300 seals were lying on a sandbank out to sea, and through the telescope we could see them swimming and sunbathing. We could also hear them across the water!

The seals were a mixture of common seals and grey seals. Grey seals like to hang out with each other and they ‘haul out’ on the sands off Hilbre for the summer months. In autumn they swim over to the Welsh coast to breed. The baby pups fatten up over the winter (a mother seal’s milk is packed with calories!) so that by the time spring and summer come around again they are big enough to learn how to catch their own food. Their special fat layer, called blubber, keeps them nice and warm in cold water. Male grey seals are larger than females and have big noses! Grey seals have grey fur with dark patches and spots. Common seals are much more rare and have rounder faces and more brownish fur.

When we walked to the end of the island we could see seals swimming in the water nearby, with some popping up to take a look at us! When they pop their heads out of the water like this, it is called ‘bottling’.

Seals have very big nostrils, which they can close tightly before going underwater. They also have extremely sensitive, bristly whiskers for sensing the movements of their prey underwater. They feed mainly on fish, squid and crustaceans such as crabs, shrimp and lobsters.

On one of our trips we were lucky enough to see a juvenile grey seal resting on the rocks! Seals are very graceful in the water but they are much more clumsy on land, so this young lady was waiting for the tide to come back in so that she could swim away more easily. Although she looked like she had a bump on her head, it is actually ear wax – seals need lots of wax in their ears to keep the water out!

After all that excitement, it was time for the long walk back to the mainland.