Bio 204 Comparative Anatomy: Rat, Earthworm, Isopod

Earthworm GI Tract

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

Rat/Rodent GI Tract

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

Isopod GI Tract

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

Earthworm Excretory

nephridia (filters ammonia and urea)

Rat/Rodent Excretory

kidney (filters blood of urea), ureters, bladder, anus

Isopod Excretory

MAXILLARY GLANDS, pleopods, hindgut, rectum, water excretory system

Mouth Comparison (ingestion)

Earthworm: mouth

Rat: mouth

Isopod: mandibles and mouth

Throat Comparison

Earthworm: PHARYNX and esophagus

Rat: esophagus

Isopod: esophagus

Stomach Comparison (digestion and storage)

Earthworm: CROP for storage and then GIZZARD for mechanical digestion

Rat: stomach

Isopod: stomach and foregut

Intestines Comparison (digestion and absorption of nutrients)

Earthworm: intestines

Rat: small intestines absorbs the nutrients

Isopod: HEPATOPANCREAS CAECA

Intestine Comparison (discharge/egestion of waste: defecation)

Earthworm: Anus

Rat: Colon, Rectum, Anus

Isopod: Rectum, Anus

Heart/Pump Comparison (movement of blood)

Earthworm: 5 aortic arches

Rat: 4 chambered heart (left + right, atrium + ventricle)

Isopod: Tubular heart w/ Ostia

Vessels (pathway to/from tissue)

Earthworm: Dorsal + Ventral blood vessels

Rat: Arteries or aorta

Isopod: Aorta, LATERAL ARTERIES, PLEOPODAL SINUSES

Type of Circulatory Comparison (open vs closed)

Earthworm: closed

Rat: closed

Isopod: open

Respiratory Organ Comparison

Earthworm: skin

Rat: lungs

Isopod: PLEOPOD