MonicaWho doesn’t love a pretty seashell?!
Seashells cover the ocean floor, they cover our coastlines and seashells fossils can be found to be millions of years old. We can’t deny the beauty of seashells, there are possibly over 200,000 Mollusks in the world and all of them create unique types of shells, with an individual Mollusks who will only ever have one shell in their whole lifetime!
Seashells cover the ocean floor, our coastlines and seashells fossils can be found to be millions of years old! There are possibly over 200,000 Mollusks in the world and all of them create unique types of shells. Did you know that an individual Mollusks will only ever have one shell in their whole lifetime??
What actually are seashells?
They are the exoskeletons of mollusks (snails, oysters, clams etc.) and are mostly made up of calcium carbonate. Seashells are a protective outer coating secreted by the animal’s mantle. They grow by absorbing salt and chemicals from the water around them and adding material at the margins; since their exoskeleton isn’t shed, molluscan shells must broaden in order to accommodate body growth.
The importance of seashells
When a mollusk dies, it leaves its shell behind, which will keep having a very important role. Dead or alive, seashells are an important part of coastal ecosystems:
-They provide materials for birds’ nests, an attachment surface for algae, seagrass, sponges, as well as a home and nutrients for other organisms.
-Fish use them to hide from predators, and hermit crabs use them as temporary shelters or mobile homes.
-Seashells also make great fertilizers. In fact, calcium carbonate helps plant growth and maintains the pH levels in the soil balanced.
-If our beaches are able to fight erosion it is also thanks to the presence of those seashells.
Whats up with all the different colours and shapes?
Yes, seashells can come in lots of different colours and shapes. The way the shell forms helps explains where the colour comes from. The material for the colour of the shell, comes from the mollusks environment, the water they are in and from what the mollusc eats. The shape, instead, has a huge effect on the environment its found in and what the mollusks needs. A smooth shell works perfectly to scoop around, whilst a spiny shell is a great protection from predators.
Any threats to seashells?
Poaching is a massive issue. We aren’t talking about someone filling up a bag with seashells, we are talking about large-scale commercial trade where shells are collected with a live mollusc still inside it. When alive and hosting a mollusc, the shell is in pristine conditions and can be sold for a higher price compared to those found on beaches, which may often be destroyed.
Climate change: Carbon dioxide from human activities, ends up in the ocean and makes the water more acidic. Seashells are very sensitive to pH changes. Over time acidic seawater increases, becomes more corrosive and will dissolve mollusk shells and harm the animals living inside.
Tourism: from shell picking as souvenirs to the disappearance of beaches for coastal construction and tractors grooming beaches. In fact, a study carried out on a beach in Spain has shown an obvious decrease in seashell abundance during the summer season compared to a much higher abundance during winter. On quiet beaches, it may not matter but the impact this action has gets bigger the more people collect shells.
TIP: It’s ok to take something from the beach but, even if it’s just one seashell, we are taking something that belongs to the natural ecosystem. Respect the environment, do some research and try understand which one of your actions may have a lower impact. Depending on the country you are in, also check its regulations and make sure you are not going against the law and the health of the coastal ecosystems.
