Earthworms play an important role in the ecosystem. They loosen soil, which makes it easier for roots to grow and for air and water to circulate, and they convert organic material into nutrients that plants can absorb. A healthy lawn or garden is typically the sign of many worms working below the ground. However, worms are slow-moving and live near the ground's surface, making them easy food sources for other animals.
According to the website All About Worms, there are several reasons why worms are part of a bird's diet. Worms are readily available in nature, slow-moving and easy to catch when near the ground surface. For these reasons, it's not uncommon to see species like the robin plucking at the grass to snatch one. Worms also contain high concentrations of protein, which birds crave. It's common for birds to feed on other insects also, but worms are large and slow enough to make an easy meal.
Moles are carnivorous animals that burrow at grass root level, because that's where their food sources are. Mole diets typically consist of grubs and worms. It's common for moles to catch worms and store them in their burrows for safekeeping. This way, they can stock up on their food source and consume them as they choose. Earthworms are high in protein, which contain the 22 amino acids animals need to function properly.
Fish are attracted to and will eat just about anything small that moves on the surface of the water, like beetles, mosquitoes and worms. Worms are also one of the most commonly used creatures to bait hooks for fishing, especially blue gill and bass. When a wormed hook is dropped in the water, fish are attracted to its movement. It makes for a more interesting snack compared to the plankton, crustaceans and minnows that make up the majority of their diets.
Box turtles are omnivores and will eat anything that smells edible to them, including snails, grasses, beetles, grass, flowers, mushrooms and earthworms. For turtles in the wild, earthworms are slow-moving, therefore making them an easy food target. Feeding pet turtles is easy too; just find out what foods they like and present the foods when they're hungry. Chopped up worms or a plate of worms mixed with greens makes for a good meal.