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Have you ever walked along Alameda’s beach at low tide and spotted little piles of squiggly sand that look like spaghetti and wonder, who made this?
The answer might not be something you'd expect! It’s not a crab, not a snail, but a lugworm. Lugworms are secret diggers living just beneath the surface of our beaches! These worms are nature’s quiet gardeners, working night and day to keep the Bay’s mudflats healthy. Without them, the beach would be a very different place!
What Are Lugworms?
What Are Lugworms?
Lugworms are a common type of segmented worm that live in burrows in the sand on our beaches. There are two types of lugworms: the Blow Lug and Black Lug. Both are soft segmented worms that burrow in the sand. They spend their lives in their burrows which are usually in a U- or J-shape bend beneath the sand. With their tails on one side of the bend and their head on the other, lugworms swallow sand and digest tiny bits of food like dead algae and plankton from the sand. The food that cannot be ingested fully is pushed back out as coiled piles on the surface. These coils can be seen once the tide goes out and they are called "casts".
Blow lugworms usually make messier, squigglier casts that look like broken pieces of spaghetti. Usually, close by to the casts, you can see a circle with a whole in the center where the entrance of their burrow is. Black lugworms, on the other hand, make neater circular piled coil casts.
It has been calculated that a typical lugworm annually “eats” 25 kg of sand, earning them the nickname of "nature's sand cleaners"!
Lungworm Vid.mp4Video Credit: lancswt.org.uk
Why They Matter
Why They Matter
At first glance, lugworms might just sound like boring old worms, but they’re actually powerful ecosystem engineers! Just like their close relatives, earthworms, lugworms have a vital role in sand turn-over on the beach. By moving around in the sand and water through their burrows, they help oxygen reach deep into the mud. Their dig-and poop routine helps break down decayed matter which allows for nutrients to be recycled back into the ecosystem. This creates fertile soil that can fuel algae and other microscopic life other animals rely on. Too much decayed matter can actually release toxins as well, making the lugworm's job even more important!
Though lugworms seem to not do much, the tiny actions they do keep the mudflats alive, which helps the whole food web above them stay strong!
So Who Relies on Lugworms?
So Who Relies on Lugworms?
Not only are lugworms relied on for their excellent sand plowing techniques, but they are also relied on as a food source. During low tide, shorebirds like sandpipers, curlews, and godwits love to snack on lugworms, making them a popular food by many birds. During high tide, crabs, fish, and rays dig into the mud for them as well! Even large animals like harbor seals indirectly rely on these worms since their prey---fish and rays---also depend on lugworm-rich mud. If lugworms were to suddenly disappear one day, the many birds we love to spot all along our shores might not find enough to eat.
Lugworms are actually used for bait by fishermen and anglers too. This process involves digging with either a spade or a bait pump in areas of coiled sand casts during low tide. They are considered an abundant and easy bait to get for fishing, however studies have showed that it could take months for the lugworm population to recover since they do not reproduce frequently. There is a growing concern that rising carbon dioxide (a gas that traps heat and makes the Earth warmer) from global warming can lead to a reduced lugworm baby survival rate. Pollution from copper can also make the mud they live in toxic, and ingestion of microplastics by lugworms could have impact on ocean ecosystems due to their importance to food chain.
Protecting our mudflats means protecting lugworms and all the creatures that depend on them. When we take care of these hidden gardeners, we take care of the Bay’s entire food web!
References: https://www.inaturalist.org/guide_taxa/181294
https://www.theguardian.com/environment/2013/dec/02/microplastic-pollution-harms-lugworms-sea-oceans
https://www.nhm.ac.uk/discover/lugworm-poos-and-the-secrets-they-hold.html
https://www.marinebio.org/species/lugworms/arenicola-marina/
https://www.wildlifetrusts.org/wildlife-explorer/marine/worms/lugworm
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