Earthworm dissection Pre-AP biology Sophie Morgan Ms. Vu
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.
- 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.
An earthworm's life cycle is very simple. They form in cocoons like butterflies, and hatch when they are fully grown.
The main habitat of earthworms is in soil, and best in damp places.
An earthworms predators are moles, birds, raccoons, ants, scorpions and other large insects.