Earthworms stay underground for a number of reasons, whether it’s summer or winter. During the summer months, the moist, dark earth keeps worms’ skin from drying out. If the skin dries out, the worm will not be able to breathe. The darkness protects the worm from the paralyzing effects of the sun. If the worm remains in the sunlight for more than an hour, it will become paralyzed.
During the winter months, worms burrow deep into the soil, oftentimes up to six feet, to escape the bitter cold. Worms can survive in temperatures ranging from 50-70 degrees Fahrenheit, but the environment must still be moist and dark. When it is cold or dry, worms are not active. When the temperature of the soil reaches around 50 degrees Fahrenheit, the worms will make their way back to the upper parts of soil and any eggs will hatch. You will notice white spots in the soil that look like pearls—those are worm eggs. But when the eggs hatch, a brown shell is left behind. The worm repeats this cycle every year.
There are more than 4,400 different types of worms. Of the 4,400 species, there are 2,700 species of earthworm. There are more than 1,200 species of another type of worm called the inchworm. Each type of worm plays a major role in helping the earth’s trees, plants, fruits, and vegetables thrive. Worms aerate the soil, which means, worms dig tunnels in the soil, allowing air to get to plant roots.
Worms also eat organic matter digest it, and excrete the digested material. This digested material is called “castings.” Worm castings are rich with phosphorus, calcium, and potassium because the worms diet consists of leaves and dead grass, which contain organisms that provide a healthy diet of bacteria, algae, and fungi. Worms also eat plants, fruits, and vegetables.
Worms eat so much that they typically produce excrement equal to their own weight every 24 hours. Worm castings are ten times richer in nutrients than commercial topsoil, making it a valuable fertilizer for gardeners and farmers. Worm castings also help create channels within the layers of the earth’s soil, which helps to hold water better and keep moisture in the soil longer.
Earthworms can be found in just about every corner of the earth. They live in trees, in bark, and under rocks as well as along rivers, near springs, and in ponds. Their favorite place to live, however, is burrowed inside the earth’s rich soil. Places like China, Australia, Greenland, and the Sahara Desert have their own indigenous species of earthworms. Besides the Sahara Desert, you won’t find large numbers of worms living in “sandy” areas, especially sandy beaches. The vast majority of worms on our planet can only survive under certain environmental conditions.
Worm Anatomy and Reproduction
Earthworms belong to one of several different types of ecological groups. There are three broad ecological groups that have been identified for earthworms including: epigeic, endogeic, and anecic. The groups are based on what the earthworms eat and where they tend to live in the soil. The epigeic group is a litter feeder, litter dweller, pigmented, small in size, and it doesn’t burrow. The endogeic group consists of rich soil feeders, topsoil dwellers, has no pigmentation, burrows horizontally, and it is small in size. The anecic consists of litter and soil feeders, soil dwellers, dorsally pigmented bodies, extensive vertical burrows, and a large size. Size and color are usually good distinguishers for adult earthworms.
The earthworm has “setae” which are tiny hair-like projections that are arranged in rows along the earthworm body. The setae are used for locomotion by the earthworm. Worms have no lungs, so they breathe through their skin. This means that the worm’s environment and skin must be moist at all times. This allows the worm to breathe in oxygen. In addition to needing a moist environment for survival, worms must also remain close to their food supply.
Although you cannot see them, worms do have mouths. The earthworm mouth is called the prostomium. The worm’s mouth is actually big enough and powerful enough to grab a leaf and drag it around. They also have a pharynx, esophagus, crop, gizzard and intestine. When the worm eats its food, it pulls the materials into its mouth with the help of the pharynx and its prostomium (also called acron). This creates a suction motion. This suction motion aids in helping the worm consume large amounts of food in a sort amount of time. The gizzard grinds the food.
The clitellum of adult earthworms contains features called genital tumescence, and tubercula pubertatis. The clitellum features, the male pores, and female pores are found above the clitellum and are all parts of the earthworm reproductive system. The earthworm’s moist sustenance rich environment plays an extremely important role in reproduction