By Piper Butterfield
November 2024

With so many species to pick from, the best way to identify a mollusc is by using a dedicated guide. Most species have several common names, and so scientific names are traditionally used. Truly one of the main benefits of identifying molluscs is their ease of handling. However, all wildlife handling must be done responsibly! I always handle shelled animals lightly and try to put them back where I found them once the ID fun is over. With this in mind, I have collated a list of suitable guides, to be found at the bottom of this post.

 

Ecosystem Importance

 

Molluscs are some of the best ecosystem drivers out there. They can provide food, habitat, cleaning services, and are a key component in nutrient cycling! Many species are known to feed on molluscs- including birds and mammals. Molluscs are an important part of the diet of Herons, Oystercatchers, and several passerines. The Snail Kite (Rostrhamus sociabilis) of the Americas is known to rely almost entirely on Apple Snails (family Ampullariidae) for food. Seals and sea lions will all happily molluscs, especially when other food sources become scarce. Even the waste products some molluscs produce become useful nutrients for other animal species.

 

Contrary to the idea of being “slimy and gross”, molluscs are particularly skilled at keeping an ecosystem clean and healthy. When a plant dies and begins to decompose, molluscs will eat the detritus, preventing it from building up and overwhelming a system. This is part of the nutrient recycling system that is fundamental to the workings of all ecosystems. When a mollusc dies, its shell will break down and enrich the nearby water and soil, and so the cycle continues. Many other molluscs feed on algae. Control of algae is very important; when algae bloom out of control, the surrounding water can become toxic, forcing the shutdown of water supplies. In 2014, half a million people in the US were shut off from water following an algal bloom in Lake Erie. Once the algae dies, bacteria thrive and cause anoxia in affected waters. This can lead to the mass death of other life in lakes where algal blooms occur, hence why molluscs are so important to the control of algae populations.

 

In addition, many of the processes molluscs perform enable environments to support more variety in species- a massive win for local biodiversity! Many mollusc species are filter feeders, eating the tiny particles that become suspended in the water column. Removal of these helps keep waters clean and clear, allowing for better light penetration. Oysters are known to cluster together and build up into reefs, creating shelter and habitat. Reefs are known biodiversity hotspots, providing shelter and breeding groups for a large range of taxa. Benthic communities also benefit, from the presence of burrowing molluscs. Bioturbation from digging activity provides an exchange of oxygen and nutrients between sediments and surrounding waters, allowing many species to thrive. Despite a basic reputation for being garden pests, it is clear that the services molluscs can provide are vital for ecosystem health.

 

The Biodiversity Literacy VIP

 

Here in St Andrews, we are very lucky to have a large range of mollusc-friendly habitats. Both Castle Sands and the far end of East Sands contain rocky habitats- great for searching for marine molluscs. The grasses around North Haugh Pond hold a range of slugs and snails, and I suspect the pond itself is the same. In Guardbridge, just outside the Eden Campus, Kentish snails (Monacha cantiana) can be found on mass, enjoying the tall grasses after a rain.