Earth Worm Dissection Parts Function Digestive System – Prostomium – a small fleshy lobe that extends over the mouth, used to help dig through the soil – Mouth – the entrance for food into the digestive system, located under the prostomium – Pharynx – A tube at the beginning of the digestive tract that creates a sucking action to remove food particles from the soil,
located just behind the mouth – Esophagus – a narrow passage in the digestive tract that connects the pharynx to the crop – Crop – a temporary storage area in the digestive tract, food waits here before it passes to the remainder of the digestive tract – Gizzard – an area in the digestive tract where strong muscles grind the food in preparation for digestion – Intestine – Nutrient digestion and absorption take place in this part of the digestive tract.
Anus – Digestive wastes are expelled through this opening located on the posterior end of the worm. Nervous system – Brain – a center of nerve cells that coordinate all of the activities of the worm’s body – Ventral nerve cord – A cord of nerves that runs the length of the body along the bottom or belly of the worm.
All nerve impulses to and from the brain are carried in this cord Circulatory System – Aortic Arches – a group of 5 muscular tubes that pump blood through the circulatory system of the worm – Ventral blood vessels – a tube structure that carries blood from the heart to the posterior of the worm located on the bottom of the worm, – Dorsal blood vessel – gathers blood from the capillaries in the body and returns it to the heart for recirculation located in the back or top of the worm Reproductive system.
Seminal Vesicles (openings) – male reproductive organs – Ovary (oviduct ovaries) – egg sack, female reproductive organs – Seminal Receptacles (openings) – temporary storage areas for the male sperm until the eggs are ready to be fertilized Other Systems – Nephridium – coiled tubes in the body of a worm that collect and excrete liquid wastes from the body of the worm. – Clitellum – a swollen area of a band around the mid-section of the body of the worm. Materials secreted from the clitellum form a cocoon in which the eggs are hatched and the young worms develop. – Setae – Bristle structures found on the skin of the worm.
Four pairs of States are found on each segment except the first and last. The state is used for movement. – Segments (somites) – The divisions in the skin of a segmented worm. The internal segments are called the septum. There can be over 100 segments in the body of a worm.