Range: Cosmopolitan Habitat: Underground in moist soil Size: Several inches - more than 1 foot (30.5cm) long Diet: Soil, dead leaves, small invertebrates, bacteria, and fungi Threats: Birds, bats, and small mammals Life span: Up to ten years depending on the species

Transcript:

Today on Animal Fact Files we’re discussing earthworms. You’ve probably seen them while digging up some dirt or maybe even on the sidewalk after a rainstorm. Earthworms need moisture to survive, so rainstorms are often a good time to move about above ground without drying out. They may also come out to avoid drowning in soaked soil.

There are thousands of earthworm species found just about everywhere in the world. Earthworms can be broken up into three groups: those who live in leaf litter, those who live in approximately the first foot of soil - also known as topsoil, and those who live below the topsoil - in subsoil - and burrow vertically down up to 6 feet (1.8m) deep! Earthworms secrete a fluid to help them move underground and to keep them moist. They need to remain moist otherwise they risk drying out.

In dry soil, they may dig to wetter areas or they may encase themselves in a mucus-lined burrow to avoid dessication. One species from New Zealand has bioluminescent fluid that glows orange in the dark! Most earthworms can not survive freezing conditions or heat over 95 degrees F (35 degrees C), though some, like ice worms, are only found in glaciers!

Although they typically only grow to be a few inches long, some of the longest earthworms, known as giant earthworms, measure over a foot (30.5cm) in length! Their bodies are made up of segments and each segment has small, hair-like structures which they use like tiny legs to move through soil. As they move about, earthworms eat the soil in which they live. Their diets include dead leaves, small invertebrates in the soil, bacteria, and fungi. In fact, an earthworm can eat up to half of its body weight in a day!

When looking at an earthworm one may wonder exactly which end is which. An easy indicator is the band or “clitellum.” If we divide the worm into three sections with the clitellum as the middle, it’s easy to figure out the rest: the shorter section is the head and the longer section is the rear-end. Although they don’t have eyes, they do have light sensitive tissue on their head. Earthworms do not have lungs. Instead, they obtain oxygen through their skin. Because of this, some earthworms quickly drown in water. However, if the water is oxygenated enough, they can continue living, and there are species that can live for days submerged.

Earthworms are hermaphroditic, meaning they have both male and female sex organs, but most still need a partner in order to reproduce. When earthworms mate, their clitellum produces a fluid around it. Each worm will pass through the other’s clitellum fluid which contains eggs and sperm. At the end of the process, they’ll produce egg cases, called “cocoons”. These are buried in the ground. On average, an earthworm produces 25 egg cases per year with up to ten eggs per case, however, some of the most prolific species produce over 100 cocoons per year! Depending on the species and environmental conditions, it can take anywhere from weeks to months for the baby earthworms to emerge. After this, it can take up to a year before they reach sexual maturity, though some take a quarter of this time.

Some earthworms may live up to ten years, though others never reach this age. Predators to earthworms include birds, bats, and small mammals. These animals may lure earthworms out by stomping on the ground to create vibrations that draw earthworms to the soil’s surface. This behavior in earthworm’s is not entirely understood but it may have something to do with them trying to avoid moles - though earthworms in areas where moles don’t exist also exhibit this behavior!

Many people believe these worms can survive if torn into pieces. Really, it depends on how and where they were cut. The worm’s head section will grow a new tail if the worm was cut under its clitellum. Some worms, like flatworms, can regrow all parts of their body. You can check them out on our flatworm episode!

For more facts on earthworms, check out the links below. Give a thumbs up if you learned something new today! Thank you to our Patrons SpikeSpiegel93, Dad, and everyone else for their support of this channel! Thank you for watching Animal Fact Files!