See what we've found on Shui Hau sandflat? A heart? A peculiar portrait? Or is this Picasso's painting work on the beach? It is actually the hunting tracks or the grazing trails left by Moon Shells (Natica spp. and Polinices spp.) or Sand Snails (Batillaria spp.) during low tide!
Sand Snails are surface-trailing snails, usually with long spiral shells, inhabiting the low-mid tidal areas of sheltered sandflats or mudflats in Hong Kong. Given their adaptability to a wide range of temperature and salinity, they could survive and live well in such a dynamic and harsh intertidal environment. Sand Snails are dominant species on the sandflat of Shui Hau. During low tide, tens of thousands of them crawl on the sandflat, just like grand columns of marching troops, which is a magnificent wonder.
Moon Shells are predatory snails. They generally hunt bivalves crawling across the sand at night, by drilling a hole on the prey's shell with their acidic secretions, followed by extension of their long feeding proboscis (i.e. tongue of a snail) to retrieve the flesh inside. Um! It's sort of cruel! So next time you find a clam shell, you may observe carefully the nice and perfect several-millimeter-size hole drilled on it. Maybe it is the masterpiece by a Moon Shell!