Worms on Earth. Earthworms.

Courtney Murphy; Mitcham; PAP Bio; 2nd period

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At a glance..

Earthworms (or Lumbricus terrestris) are a member of the Kingdom Animalia, the phylum Annelida, the class Oligochaeta, and the order Megadrilacea. They are a segmented animal, commonly found in soil. They feed on live and dead matter. Their bodies are soft and round and usually a cylinder-like shape. Earthworms are part of the trophic level Decomposers.

Ecological Niche

Soil-dwelling earthworms fall into three main niche groupings: compost and soil-surface dwellers (epigeic), topsoil dwellers (endogeic) and deep-burrowing subsoil dwellers (anecic).

Earthworm's role to the ecosystem..

Earthworms are sometimes known as ‘ecosystem engineers’ because they significantly modify the physical, chemical and biological properties of the soil profile. These modifications can influence the habitat and activities of other organisms within the soil ecosystem.

Backround Info

Sample Earthworm Dissection

Earthworm Dissection

Digestive System Close Up

The digestive system is partitioned into many regions, each with a certain function. The digestive system consists of the pharynx, the esophagus, the crop, the intestine and the gizzard. Food such as soil enters the earthworm’s mouth where it is swallowed by the pharynx. Then the soil passes through the esophagus, which has calciferous glands that release calcium carbonate to rid the earthworm’s body of excess calcium. After it passes through the esophagus, the food moves into the crop where it is stored and then eventually moves into the gizzard. The gizzard uses stones that the earthworm eats to grind the food completely. The food moves into the intestines as gland cells in the intestine release fluids to aid in the digestive process. The intestinal wall contains blood vessels where the digested food is absorbed and transported to the rest of the body.
Earthworm Digestive & Circulatory Systems

Video explaining earthworm anatomy..

Earthworm Anatomy

Earthworms help the environment too...

Earthworms are more than just fish bait. They are the main contributors to enriching and improving soil for plants, animals and even humans. Earthworms create tunnels in the soil by burrowing, which aerates the soil to allow air, water and nutrients to reach deep within the soil. Earthworms eat the soil which has organic matter such as decaying vegetation or leaves. Plants cannot use this organic matter directly. After organic matter is digested, the earthworm releases waste from their bodies called castings. Castings contain many nutrients that the plant can use. Some people even use earthworm castings as garden fertilizer.

Human Impact/Influence

The quality of our soil depends heavily on the activity of earthworms. Earthworms compost, break down inorganic matter and also aerate soil. Earthworms are also a food source for many other creatures.

The way we treat the land through some farming and gardening practices seriously threatens the earthworm. Plowing kills worms, as do pesticides and chemical fertilizers. When the worm population is destroyed, more chemicals are needed to keep the land productive, it's an ongoing cycle.

Cladogram

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Cool earthworm facts!

  • Lacking lungs or other specialized respiratory organs, earthworms breathe through their skin.
  • The skin exudes a lubricating fluid that makes moving through underground burrows easier and helps keep skin moist. One Australian species can shoot fluid as far as 12 inches through skin pores
  • Each earthworm is both male and female, producing both eggs and sperm.
  • In one acre of land, there can be more than a million earthworms.

  • The largest earthworm ever found was in South Africa and measured 22 feet from its nose to the tip of its tail.

  • Earthworms have the ability to replace or replicate lost segments