Wiggling Inside an Earthworm
Earthworm Dissection Lab
Cecilia Compean
04/09/14
Vu-PAPBio-3rd
Objective
- Describe the appearance of various organs found in the earthworm.
- Name the organs that make up various system in the earthworm.
Background Information
The earthworm, Lumbricus terrestris, is a memeber of the phylum Annelida. An earthworm is well-adapted to a life of burrowing through the soil. Its streamlined shape helps it move through the soil. One of the main predators of the earthworms are birds.
Earthworm Circulatory System
The earthworm like many more complex organisms has a closed circulatory system, meaning that its blood is confined to blood vessels and its blood is recirculated so it gets maximum use. An earthworm has neither lungs nor gills but uses its body's great surface area to absorb oxygen from the soil. The oxygen is taken in by the dorsal blood vessel and travels to the five aortic arches (hearts) by the esophogus where it is pumped to the lower, ventral blood vessel. The ventral blood vessel pumps the blood to all segments and organs in need of oxygen. In each segment, there is a small blood vessel that sends the blood from the ventral blood vessel back to the dorsal blood vessel, thus completing the loop (Musurca).
Other Info
-There are approximately 2,700 kinds of earthworms
-The largest earthworm was found in South Africa and measured about 22ft
-Charles Darwin spent 39 years studying earthworms
-Worms are cold-blooded animals
Taxonomy
Cladogram
Evolution
An earthworm has a streamlined body with no antennae or fins or arms or legs! This streamlined shape is an adaptation to living in narrow burrows underground and the need to move easily through the soil.
Ecology
Habitat: soil
Predators: birds
Prey: dead organisms
Trophic Level: decomposers
Body System
1. Crop - food storage
2. Mouth - opening for food to enter
3. Pharynx - muscle to suck in food(dirt)
4. Intestine - digestion of food
5. Gizzard - grinding food
6. Anus - where wastes exit
7. Esophagus - tube where food is passed from mouth to crop
8. Pharyngeal Muscles - supports pharynx, sucks in food
Human Influnce
Gardeners tend to like earthworms because they mix the soil, loosening it and moving nutrients around. Earthworms even shred leftover plant parts into smaller fragments eaten by microorganisms. In these ways, earthworms can improve and enrich the soil, allowing garden and certain crop plants to grow better.