Bio 204 Anatomy, Function, and Comparable structures

Earthworm GI organs

mouth, pharynx, esophagus, crop, gizzard, intestine, anus

Earthworm Excretory Organs

Nephridia

Earthworm Circulatory organs

5 aortic arches (pseudo hearts), dorsal and ventral blood vessels

Rodent GI organs

mouth, esophagus, stomach, liver, pancreas, small intestine, colon

Rodent Excretory Organs

kidney, ureters, bladder, anus

Rodent Circulatory Organs

Atria, ventricles, arteries, capillaries, veins

Isopod GI organs

mandibles, maxilliped, mouth, esophagus, stomach, foregut, hepatopancreas caeca, hindgut, rectum and anus

Isopod Excretory Organs

maxillary glands (end sac, valve, and excretory duct), water conductance system (WCS), hindgut, and rectum

Isopod Circulatory Organs

aorta, heart (ventricle), accompanying arteries, lateral cardiac arteries, pleopodal sinuses, pericardial space, and ostia

Earthworm - Mouth: opening to digestive system, food gathering

Mouth - aids in capturing food

Pharynx - acts as suction pump to draw food particles and soil into the digestive tract

Rodent - Mouth: opening to digestive system, food gathering

Mouth - Food goes from the mouth

Pharynx - aids in food movement

Esophagus - food passage

Epiglottis - covers trachea so food doesn’t enter respiratory tract

Isopod - Mouth: opening to digestive system, food gathering

Mouth - entry point to the digestive system (has mandibles and maxillipeds to pass food)

Worm - Throat-esophagus: link to digestive organs

Esophagus - a tube that moves food from the pharynx to crop

Rodent - Throat-esophagus: link to digestive organs

Pharynx - food flows to the esophagus

Esophagus - contains skeletal muscle that allow for food movement

Isopod - Throat-esophagus: link to digestive organs

Esophagus - a narrow, muscular tube that connects the mouth to the digestive system

Worm - Stomach: digestion and storage

Crop - stores ingested soil and ingested matter and moves it to the gizzard

Gizzard - grinds ingested food and soil to allow for further digestion in intestine

Rodent - Stomach: digestion and storage

Forestomach - digestion starts here

Glandular stomach -  acid and enzymes break down food

Isopod - Stomach: digestion and storage

Stomach (foregut) - primary site for initial digestion and temporary storage of food; helps to regulate movement of food through digestive system

Worm - Intestine: digestion and absorption

Intestine - responsible for digesting food and absorbing nutrients and using muscular walls to mix food

Rodent - Intestine: digestion and absorption

Small intestine - food breakdown with enzymes from pancreas and nutrient absorption

Isopod - Intestine: digestion and absorption

Intestine (midgut) - continues the process of digestion and is the primary site for nutrient absorption; nutrients absorbed into the body to support energy needs

Hindgut - remaining waste passes through for excretion

Worm - Intestine: egestion

Intestine - process and expels undigested waste materials through anus

Rodent - Intestine: egestion

Egestion responsible for getting rid of undigested food and other waste

Isopod - Intestine: egestion

Hindgut - responsible for egestion; waste is compacted and passed through the hindgut to be expelled; maintains internal balance and removes unusable material

Worm - Nitrogenous waste excretion

Nephridia - contains tubular organs and discharges nitrogenous waste via nephridiopores (external opening)

Rodent - Nitrogenous waste excretion

Urine (urea) - excretes nitrogenous waste

Kidneys - help maintain water balance and control excretion

Isopod - Nitrogenous waste excretion

Ammonia/urea - excretes nitrogenous waste

Maxillary/antennal glands - filter waste from the hemolymph (isopod body fluid)

Excretion system helps regulate the internal chemical balance while conserving water in dry environments

Worm - Heart or pump: moves blood

5 aortic arches (pseudo hearts) - contracts to pump blood throughout their body

Rodent - Heart or pump: moves blood

4-chamber system (bi-circulatory system) - pulmonary circuit and systemic circuit pump deoxygenated blood (right side) to the lungs and left side (systemic) pump oxygenated blood to the rest of the bodyIs

Isopod - Heart or pump: moves blood

Heart - a long, tubular structure located along the back of the body. Pumps hemolymph (similar to blood) through an open circulatory system

Ostia - small openings that allow hemolymph to re-enter the heart and continue circulation

Worm - Vessels: pathway to/from metabolically active tissues, isolation, efficiency

Dorsal and ventral blood vessels

Dorsal bvs collects blood and pumps it toward head of body

Ventral bvs distributes blood to other parts of the body

Rodent - Vessels: pathway to/from metabolically active tissues, isolation, efficiency

Arteries take blood from the heart to other parts of the body

The right side of the heart takes deoxy. blood from body to pumps it to lungs to be oxygenated

Isopods - Vessels: pathway to/from metabolically active tissues, isolation, efficiency

The circulatory system is open, lacking a closed network of blood vessels; short arteries direct hemolymph toward metabolically active tissues.

Hemolymph flows freely through the body cavities before returning to the heart

Well-suited to the isopod’s small size and low metabolic demands

Primary organ of respiration for worm

Skin

Primary organ of respiration for rodent

Lungs

Primary organ of respiration of isopods

Pleopods

Movement of gases in respiratory organs for worm

CO2 moves from capillaries from skin to air, and O2 moves from air to mucous to skin, then crosses the skin into capillaries (down concentration gradient)

Oxygen carrier protein in the blood is a type of iron-containing hemoglobin called erythrocruorin

Movement of gases in the respiratory organs for rodents

Pressure gradient - Air moves into the mouth, then the trachea, bronchi, bronchioles, and then the alveoli

Gas exchange results in CO2 moving from pulmonary capillaries into alveolar air, and O2 moves from alveolar air into pulmonary capillaries

Oxygen carrier protein in the blood is the iron-containing hemoglobin

Movement of gases in the respiratory organs for Isopods

CO2 from hemolymph diffuses through the air tubes to the outside pleopod. Oxygen enters spiracles/openings in exopodites of pleopods—Traverses air tubes to sinuses.

Oxygen carrier protein in the hemolymph is the copper-containing hemocyanin.