The slimy earthworm
Created by : Alonso Gonzalez Ramirez Mitcham pd. 2
Background information
Most people know earthworms as those squiggly things in the soil. Earthworms play a major role in their environment and are the reason we can have such luscious gardens. Earthworms break down decaying plant matter, their waste is extremely fertile, and their tunnels aerate the soil allowing root systems to grow better. Earthworms are hermaphrodites meaning they have both male and female organs. Their offspring are wrapped in a cocoon that protects them until they hatch.
Ecology
Earthworms play an amazing role in their ecosystem. They are a reliable food source and an efficient decomposer. Their populations so are easy to maintain that there are captive worm farms for gardening. Earthworms break down decaying plant matter and produce nutrient rich waste for plant soil. Their tunneling breaks up the soil for plant roots and helps to aerate the soil. Earthworms are hermaphrodites and produce cocoons in which their eggs are laid. After a period of time the miniature versions of their adults climb out and begin to grow. Birds and many other animals prey on worms or indirectly eat the plants they help to grow. All in all they are key to their ecosystem
Evolution
Earthworms are a very basic and primitive creature. They have no skeletal system, no brain, not even a true heart. The earthworm does have cilia which are small external hairs that help with locomotion and a simple closed vascular system. Earthworms are also hermaphrodites having both male and female parts. Their segmentation puts them in phylum Annelida and their clitellum puts them in class clitellata.
Taxonomy
Phylum: Annelida
Class: Clitellata
Order: Haplotaxida
Family: Lambricicdae
Genus: Lumbricus
Species: Terrestris
Today's objectives
Earthworm Circulatory System
Earthworms have a simple close circulatory system, meaning the blood is contained inside the organism. A group of aortic arches act as the heart and constrict the dorsal vessel pumping blood throughout the organism. The blood from the dorsal blood vessel goes to the ventral blood vessel which then completes the circulatory loop. The dorsal blood vessel supplies the dorsal side with blood and the ventral blood vessel supplies the ventral side with blood.
Body Systems
Earthworms has a circulatory, excretory, reproductive, and digestive systems. The circulatory system consists of the aortic arches and the dorsal and ventral vessels. The aortic arches act as hearts and constrict the vessels moving blood through the organism. The excretory system consists of the intestines and the anus. The intestines stretch the length of the organism until the waste is excreted by the anus. Worms are hermaphrodites and contain seminal vesicles and receptacles which produce reproductive gametes. The digestive system consists of the mouth, esophagus, crop, and gizzard. The crop holds the food and the gizzard performs the mechanical breakdown of the food.
Human Impact
FUN FACTS
- There are about 2,700 different kinds of earthworms
- One acre of land can house more than a million worms
- the largest earthworm was in south America at 22 feet long
- Charles Darwin Spent 39 years studying earthworms