Lumbricus terrestris Is a segmented worm or ANNELID The Earthworm Lumbricus terrestris Is a segmented worm or ANNELID

NUTRITION: The Earthworm has a one way digestive tract: From mouth to anus Food Enters at the mouth, passes through the esophagus and crop, and is stored in the crop. In the gizzard food is crushed. The gizzard is a muscular sac which clenches. The grit in the dirt a worm eats scrape and crush organic particles present. This is mechanical digestion. The intestines secretes hydrolytic enzymes which break down food. This is chemical digestion. Wastes pass out through the anus. Is this intracellular or extracellular digestion?

Digestive Tract Pharynx Crop Intestines Mouth Esophagus Anus Gizzard

TRANSPORT Since the worm has many cells NOT in contact with the external environment, it needs a circulatory system to distribute materials throughout its body. It Possesses a CLOSED circulatory system: It has blood vessels to contain the blood.

BLOOD Contains red pigment called Hemoglobin It carries oxygen. Blood is moved through the vessels by the pumping of 5 pairs of Aortic Arches (hearts). The exchange of materials takes place between blood and body cells through the walls of the smallest blood vessels called capillaries.

The Circulatory System

The Intestine Is infolded to increase surface area for pickup of nutrients by the blood. This is called the absorption

Respiration Gas exchange of respiratory gases takes place by diffusion through the thin, moist skin. It is kept moist (down right slimy!) by mucus secretion. Carbon dioxide diffuses right out

Excretion Nephridia filter out excess water, mineral salts, and urea from blood and excrete them They are found in pairs in most segments Nephridia work like our kidneys

REGULATION Worms have a primitive Brain and Nerve Cord. These make up the Central Nervous System The brain is in the anterior (head) end of the worm and consists of ganglia, or masses of nerve cells The nerve cord runs along the vental or lower side of the worm, with a ganglion in each segment

Am I getting on your NERVES? Peripheral Nerves run from the brain and nerve cord and serve all parts of the body. Impulses travel in one direction over definite pathways. Fused Ganglia Peripheral Nerves Ganglion Nerve Cord Nerve ring

LOCOMOTION 2 Sets of Muscles: One set makes the worm stretch out, the other makes it short and fat Setae are pairs of bristles on the underside of most segments. These give the worm traction in the dirt.

Dorsal Blood vessel Setea Nephridia Ventral Blood Vessel Ventral Nerve Cord