Country diary: Camouflaged riches on the shore | Claire Stares

Hayling Island, Hampshire: In among the debris were several mermaid's purses like aged leather. Identification would require hydrating themIt was low tide and forecast to be relatively calm, but when we arrived at the beach, white-crested waves were surging along the shore. Abandoning our plans to swim, we decided to beachcomb instead. The high tide had deposited a thick band of decomposing seaweed, shells and other debris on the strandline. As I pocketed an iridescent pink-lined scallop shell, my attention was drawn to a piece of driftwood with peeling turquoise paint. Crouching down to pick it up, I realised it was surrounded by mermaid's purses - the cast-off eggcases of cartilaginous fish - that had been perfectly camouflaged against the dark ribbons of kelp.These protective capsules are made from a combination of collagen and keratin, giving them a similar texture to human fingernails. Keratin is a fibrous protein, tough enough to deter predators and insoluble in water, waterproofing the eggcase when it is first laid. This is vital to protect the embryonic pup within, which won't develop gills until it's several weeks old. Later, small holes open in the capsule's four horn-like projections, allowing the embryo to continuously pump in fresh, oxygenated seawater by beating its tail. Continue reading...