Most people have experienced the excitement of rockpooling. No matter how old you are, there is something fascinating about taking a glimpse into these tiny underwater worlds. However, despite my love of rockpool creatures, I want to instead introduce you to strandline searching, also known as beachcombing.
What is a strandline you ask? The strandline is the line of seaweed, driftwood and other debris deposited on the beach by the waves. Strandlines are dynamic, changing with the tides and particularly altering in stormy conditions when more material is washed up. Now this may not sound too interesting, but there are treasures to be found here if you know what to look for! The first thing you will observe is the tangle of seaweed along the strandline, which is likely to consist of a variety of species such as Bladder wrack (Fucus vesiculosus), Sea lettuce (Ulva lactuca), Serrated wrack (Fucus serratus), and Oarweed (Laminaria digitata). Strandline searching often involves getting your hands dirty and sifting through this seaweed to see if anything is hiding in the tangle!
Now my absolute favourite natural objects to find along the strandline are mermaid’s purses. These are elasmobranch eggcases that belong to sharks, skates or rays. Most elasmobranch species are viviparous, meaning that they give birth to live young. The remainder are ovoviviparous meaning that embryos develop in eggs that stay inside the mother until they are ready to hatch, or oviparous, meaning that they lay eggs. Once laid, these eggs are left on the seabed to develop, unprotected by the parents. Some eggcases have long tendrils which help them to anchor to the rocky seafloor or seaweed. The eggcase is formed from a fibrous protein called collagen, creating a tough and protective capsule. Each eggcase contains one embryo and a yolk sac which provides the developing elasmobranch with nutrition. Small slits form to allow oxygenated water to enter the eggcase. As the embryo develops, it beats its tail to actively pump seawater into the case. The embryo eventually absorbs the yolk sac and develops into a pup. Once fully developed, the pup bites its way out of the eggcase and emerges into open water!
You will predominantly find eggcases washed up on the strandline empty, after the animal has hatched. These are often dry and appear smaller than their usual size. You can rehydrate an eggcase by soaking in water for a few hours, to return it to its original size and flexible shape. However, you may sometimes find an eggcase with a live embryo inside! You should be able to tell by holding the eggcase up against the light. If you think you have found a live eggcase, quickly return it to the sea. The species of shark, ray or skate can be identified by the size and shape of an eggcase. An ID guide is useful in doing so. As a rule of thumb though, sharks tend to lay more elongated eggcases with curly tendrils. Whereas rays and skates tend to lay squarer eggcases with horns protruding from each corner. The Shark Trust provide handy ID charts, and a form to record your sightings on their website. You can also download their App ‘Eggcase Hunt’ to easily identify and record mermaid’s purses on the go!
Another type of egg which you can find washed up on the strandline are those of the Common Whelk, sometimes known as egg clouds. These strange spongy masses are a collection of up to 2,000 egg capsules. Each capsule contains hundreds of eggs, but only some are fertilised.
Depending on the time of year, something you could find in abundance washed up on the beach are jellyfish, with large blooms of most species appearing in the spring and lasting through to autumn. These animals are not classed as fish but as Cnidarians; along with corals and sea anemones. They prey on plankton, crustaceans, fish eggs, small and juvenile fish… and even other jellyfish! Common species seen in the UK range from the translucent Moon jellyfish (which has four distinctive purple rings), the yellow/ brown Compass jellyfish (which has darker V shaped markings around the entire bell), the Blue jellyfish (which is beautiful deep blue), or the white/ pink Barrel jellyfish (which can grow up to a huge 1 metre in diameter!) Another wonderful find, which is often mistaken for a jellyfish, is the By-the-wind-sailor. Commonly found floating on the surface of water (or washed up on the strandline), they are similar to the Portuguese Man O'War as they are made up of a colony of tiny individual animals called hydrozoans.
Seashells are of course a firm favourite to discover on the beach, with all kinds of beautiful shapes, colours and patterns. However, crab shells are also an exciting find! These are often not from a dead crab but have instead been moulted as a crab has grown. Species to look out for include the Edible crab, Common shore crab, Spider crab, and Velvet swimming crab.
Something which is technically not a natural object but is a beautiful find, is sea glass. This is glass which has entered the ocean and slowly been smoothed after years of tumbling in the waves. They often have a frosted appearance and can be found in a huge range of colours. On the other hand, a less welcome manmade find is litter. From tiny pre-production plastic pellets called nurdles, to much larger objects, a huge amount of litter is left or washed up on the shoreline. Much of this litter often ends up tangled amongst the seaweed on the strandline, so a strandline search can also be the perfect opportunity to carry out a litter pick!
Happy strandline searching!
