Earthworm

Earthworm dissection Pre-AP biology Sophie Morgan Ms. Vu

Lumbricina

The earthworm belongs to the Kingdom Animalia, Phylum Annelida and Class Oligochaeta. Earthworms eat dirt. Their nutrition comes from things in soil, such as decaying roots and leaves. Animal manures are an important food source for earthworms. They eat living organisms such as nematodes, protozoans, rotifers, bacteria, fungi in soil. Adaptations are bristly hairs on each segment, a body with no appendages, circular muscles in each segment, and pulls its food inside of the mouth area. They have also developed the ability to secrete a slim that helps them move along different types of surfaces.

Little body, Big process. The digestive system.

An Earthworm’s digestive system consists of the mouth, pharynx, esophagus, crop, gizzard and intestine. The mouth is surrounded by strong lips that act like a hand would. Since an earthworm does not have teeth, bits of soil particles are used to help them “chew” their food. The food particles pass from the mouth to the pharynx. Next, the food is temporarily stored in the crop where they will get mixed together. From the crop, the mixture enters the gizzard where the actual digestive process begins. The powerful muscles of the gizzard mix the mass of food and dirt. Glands in the walls of the gizzard add enzymes, which aid in the chemical breakdown of the organic material. Next, the mixture is sent to the intestine. The intestine has bacteria that eats the food mixture. While the mixture is being eaten it releases vitamins, minerals, carbohydrates, and proteins from the organic matter; this supplies everything the worm needs in order for him to absorb it into his body. Most of the worm’s body length is intestine. It is lined with thousands of finger-like projections that are filled with small blood vessels. The blood vessels help to absorb the liquefied food. Finally at the end of the intestine, the soil particles and undigested organic matter pass out of the worm’s body through the anus.

Nifty Facts!!

  • The study of worms is called helminthology.
  • 90% of their body weight is water weight.
  • They have five hearts
  • There are thousands of different kinds of worms
  • There are four main groups of worms

Flatworms, or Platyhelminthes;
Ribbon worms, or Nemertea
Roundworms, or Nematoda; and
Segmented worms, or Annelida.