So you spotted a worm that looks like it might be carrying a pouch or case filled with sand? Really? Well, you can relax. Chances are, you were not imagining things. Case carrying worms do exist and you are lucky to have seen one! There are several types of worms that have the amazing ability to carry pouches or what appears to be a little case. What’s even more amazing than this is the case or pouch can be made of a number of materials such as silk, a cement-like substance or even sand.

Never underestimate the power of a worm. After all, our plants, trees, and flowers could not survive without them. These amazing, yet complex creatures (earthworms), are the world’s largest group of worms. Most of the more than 2,700 different species of earthworm help plants and trees grow by aerating the soil. They do this by digging tunnels in the soil, which allows air to get to the plant roots.

Earthworms also eat organic matter, digest it, and excrete the digested material appropriately called “castings.” Castings are rich with calcium, phosphorus, and potassium and they are a whopping ten times richer in nutrients than commercial topsoil. As a result, many savvy gardeners and farmers use the composting method alone to fertilize plants and crops.

Worm castings also help create channels within the layers of the earth’s soil. This helps hold water better and keep moisture in the soil longer. Although case carrying worms do not aerate soil, they are just as amazing. Let us explain why.

Worms called gastrotrichs have bodies covered with tiny tubes that secrete a cement-like substance. The cement tubes make it appear as though the worm is carrying a case filled with sand. Gastrotrichs belong to the phylum gastrotricha. These tenpin-shaped ciliated worms are made up of 13 families and they all have cuticular adhesive tubes. While gastrotrichs do not inhabit and enrich the earth’s soil, they do live in sandy areas and beaches helping to prevent decay and odor by consuming debris in the surrounding area and water.

Another type of “case carrying” creature is the larvae of caddisflies. The larvae can be found in a wide range of habitats such as ponds, lakes, springs, and streams. Many species have the ability to make protective cases made of silk. The larvae covers the protective case with twigs, gravel or sand. Also called sedge-files and rail flies, the adult caddisfly is also a case-maker. It makes a portable case of silk mixed with plants, rock, twigs or sand. In some cases, the caddisfly uses silk alone to create its case, but for the most part, the creature covers it with sand or other debris. Over time, the caddisfly case grows, giving the caddisfly the appearance of a bagworm.

For the most part, the adult stage of caddisflies lasts only 1-2 weeks. In a few cases, the adult stage can last for 2 months. Most adults are non-feeding and well equipped to mate. The female caddisfly will lay her eggs anywhere below or above the water surface. She uses a gelatinous substance to enclose and attach the eggs to the surface. It can take up to three weeks for the eggs to hatch, sometimes sooner. In general, Caddisflies will complete their lifecycles in one year.

The following image illustrates just how some artists ‘see’ these amazing case carrying worms. Enjoy!

Duprat’s aquatic caddis fly larvae.