Key Characteristics
*Annelids have segmentation and are coelomates
*They are triploblastic, have bilateral symmetry and cephalization
*Have a closed circulatory system
*Have chaeta (bristles used for traction, burrowing, and swimming)
*Body segments are separated by septa, internal walls
*The digestive tract is divided into several parts, each with a specific function
*They are hermaphrodites but they do cross-fertilize during sexual reproduction
*Classes include oligochaetes, polychaetes, and hirudinea
*There are about 12,000 species
Habitat
They live in areas in or around water such as lakes, oceans, glaciers, and moist soil.
Interesting facts
1. Annelids can range from a size of 1 millimeter to over 3 meters long
2. Some are parasitic and some are not
3. Some annelids can survive being frozen for extended periods of time
4. The annelids that do not have eyes are extremely light sensitive.
5. If the worm is punctured, it loses its ability to move properly, since functioning of the body muscles is dependent on the maintenance of the fluid volume in the coelom.
Examples
1. Earthworms
*Annelids have segmentation and are coelomates
*They are triploblastic, have bilateral symmetry and cephalization
*Have a closed circulatory system
*Have chaeta (bristles used for traction, burrowing, and swimming)
*Body segments are separated by septa, internal walls
*The digestive tract is divided into several parts, each with a specific function
*They are hermaphrodites but they do cross-fertilize during sexual reproduction
*Classes include oligochaetes, polychaetes, and hirudinea
*There are about 12,000 species
Habitat
They live in areas in or around water such as lakes, oceans, glaciers, and moist soil.
Interesting facts
1. Annelids can range from a size of 1 millimeter to over 3 meters long
2. Some are parasitic and some are not
3. Some annelids can survive being frozen for extended periods of time
4. The annelids that do not have eyes are extremely light sensitive.
5. If the worm is punctured, it loses its ability to move properly, since functioning of the body muscles is dependent on the maintenance of the fluid volume in the coelom.
Examples
1. Earthworms
2. Leeches
3. Sandworms