Earthworms-+Stephanie

The Earthworm Science Report by Stephanie Grob

Introduction: Earthworms are invertebrates belonging to the scientific group called Annelida (segmented worms). Earthworms are one of the most important creatures on our planet. They move through the soil and mix the soil together, this makes it easier for water to get through the soil to reach roots of plants. They also chew fallen leaves and animal remains and the waste they produce acts as fertiliser, improving the quality of the soil. Earthworms live in all areas of the world where there is soil. There are about 2,700 different species of earthworms.

** Earthworm in soil **

Habitat: Earthworms are found in soil leaf litter and under stones and logs in most types of habitats (both hot and cold). However, most species are found in wetter parts of the world. Every day you’ll find earthworms mixing up soil and fertilising it. They live in their burrow, which they make by digging into the soil.

Anatomy: Earthworms grow in ranges of sizes, from 1 centimetre to over 2 metres long. As invertebrates, earthworms don’t have bones and the body is soft, wet and slimy. The front (anterior) end of a worm is where the head and mouth are located. The back (posterior) end is the tail end. The body of an earthworm is divided into 120-170 little rings called segments. On each segment are four pairs of hair (called setae) which help them move. There is a bump on the anterior part of each earthworm called a clitellum. The clitellum is important for mating and making cocoons, which is part of their reproduction process. Important body parts for eating and digestion are the pharynx, esophagus, crop, gizzard and intestine. Muscle contractions of the Pharynx pull food from the mouth into the esophagus where it is temporarily stored in the crop. When the food reaches the gizzard it is ground up before being digested in the intestine. Earthworms have five hearts but no lungs. They breathe through their skin and must be coated in mucus so oxygen can reach their blood.
 * Earthworm burrow **
 * Earthworm anatomy **

Feeding and Predators: Earthworms eat decaying roots and leaves and living organisms such as bacteria and fungi. They also swallow soil as they burrow through it, and the nutrients are absorbed as the soil passes through the digestive organs. Earthworms do not have teeth but have strong mouth muscles to pull food into the digestive tract. They pull leaves and other larger organic material into their burrow and take small bites once they soften and decay. Birds, snakes, toad, beetles, centipedes, leeches and slugs eat earthworms and are their predators.

Food Chain:



Reproduction: Earthworms are hermaphrodites, which means that all earthworms produce eggs and have both female and male parts. When two earthworms mate, they lie next to each other and cover themselves with a sticky mucus that they secrete from their clitellum (which is the ‘bump’ shape on the middle of their body). They pass sperm into each other’s body which then fertilises an egg inside the other earthworm’s body. A thick ring of slime then forms around each earthworm and the worms wriggle forward so that a ring with eggs in it forms and closes at both ends to become a hard cocoon that protects the eggs. ** Earthworms mating ** Lifecycle: Usually one or two earthworms hatch out of each egg and the time this takes depends on the weather. If the weather is warm, the earthworms may hatch after two weeks. But if it is cold, it may take up to three months. Earthworms are about 12 millimetres long when they hatch. Once the earthworm hatches, they burrow into the soil where they eat and grow. It takes 12 months for an earthworm to grow to be an adult. Did you know?
 * Earthworm lifecycle **
 * Did you know that earthworms don’t have any eyes but can sense light? This means they know if its day or night and when a predator is outside their burrow.
 * Did you know that in one square metre of soil there can be up to 250 earthworms?
 * Did you know that earthworms must be kept wet or they will die?
 * Did you know that earthworms come to the surface when it is wet because it is easier and safer for them to move on wet ground? This makes it easier to find a mate.
 * Did you know that earthworms have been kept alive for six years in a laboratory, but in the wild they will probably only live for two years at the most?
 * Did you know that earthworms can eat up to one third of their body weight in food each day?
 * Did you know that the scientific name for the earthworm is //Lumbricus terrestris//?
 * Did you know that if you cut an earthworm in half, its end (posterior) portion will grow back?