EyeThe large eye on top of the head. Its lower lid is thin and see-through and can be drawn up over the eye.
NostrilOne of two small openings on top of the snout. They lead through to the roof of the mouth.
MouthA wide slit running back from the tip of the snout.
Tympanic membrane (eardrum)The frog's eardrum: a round patch of skin just behind the eye. Frogs have no outer ear.
Fore limbThe short front leg: arm, forearm and a hand with four fingers.
Hind limbThe long back leg, folded up at rest: thigh, leg and foot. It is much longer than the fore limb, for leaping.
Webbed footFive long toes joined by webs of skin for swimming.
Cloaca (vent)The single opening at the back end of the body. Waste from the gut and urine from the bladder both leave through it.
Inside: 10 10
HeartThe heart, in the middle between the lungs. A frog's heart has three chambers.
LungsTwo thin, stretchy sacs beside the heart, partly hidden under the liver. A frog also breathes through its skin.
LiverA large reddish-brown organ with two lobes, just below the heart. It makes bile.
GallbladderA small sac between the lobes of the liver. It stores the bile the liver makes.
StomachA curved sac under the liver's left lobe. Food is churned and digestion begins here.
PancreasA small organ near the stomach. Its juice flows into the small intestine and helps digest food.
Small intestineThe long, coiled tube where most food is digested and taken in.
Large intestineThe wide tube at the back of the gut. It takes water from the waste before it goes out through the cloaca.
KidneysTwo long, dark red organs against the back wall. They take waste out of the blood.
BladderA thin-walled, two-lobed sac at the back end of the body cavity. It stores urine.
How this list was compiled: Read 2026-09-27. (1) A. Milnes Marshall, The Frog: an Introduction to Anatomy, Histology and Embryology, 5th edition (1894), https://archive.org/details/frogintroduction01mars : the eyes with a thick upper lid and a thin, freely moveable lower lid; the tympanic membrane behind the eye; the fore limb of arm, forearm and hand with four digits; the hind limb of thigh, leg and foot with five webbed toes, much longer than the fore limb; the mouth; the nostrils or anterior nares; the cloacal aperture; the heart between the lungs; the bilobed liver; the gall bladder; the stomach under the liver's left lobe; the pancreas; the small intestine and the wider large intestine; the kidneys; the bilobed bladder. (2) Wikipedia, Frog, https://en.wikipedia.org/wiki/Frog : no external ears, the tympanic membranes visible just behind the eye; eyelids and a nictitating membrane; a three-chambered heart; breathing with lungs and through the skin; the oesophagus, stomach, small intestine and large intestine; the liver, gall bladder and pancreas; two kidneys, the urinary bladder and the cloaca; webbed feet in aquatic frogs. Licence: own work
The drawing: Drawn for this site by script, 2026-09-27. Own work, nothing traced. Licence: own work
How it works
An unlabeled frog diagram for a lab handout or a study night: the frog from the side above, the opened frog below. Eighteen lines run out from the parts, and nothing is written at the end of any of them.
Read the full guide
The eight lines on the upper frog
They end on the eye, nostril, mouth, tympanic membrane, fore limb, hind limb, webbed foot and cloaca. For simple blank frog labeling with a younger class, stop here and leave the lower drawing for later.
The ten lines on the opened frog
They end on the heart, lungs, liver, gallbladder, stomach, pancreas, small intestine, large intestine, kidneys and bladder. The frog lies on its back, so its left side is on your right: the stomach, which sits on the frog's left, is drawn on the right.
Name the liver before the lungs. The liver is the wide two-lobed organ; the lungs are the thin sacs showing above it, beside the heart.
Blank labeling the anatomy of a frog is easier from the head end down: the organs lie in that order, heart first and bladder last.
Questions and answers
What are the parts of a frog to label?
Eighteen on this sheet: eight on the outside, from the eye to the cloaca, and ten organs inside, from the heart to the bladder. The pupil, the toes and the folds of skin are drawn but have no line.
How do you tell the small intestine from the large intestine?
The small intestine is the long coiled tube that leaves the stomach. The large intestine is the wide straight tube after it, running down the middle to the cloaca.
Where are the kidneys on a dissected frog?
Against the back wall of the body, behind the gut. In this drawing they are the two long organs on either side of the large intestine, above the two-lobed bladder.
Does the frog diagram come with an answer key?
Yes. The key is this sheet with a name at the end of every line. The tympanic membrane and the cloaca carry their everyday names too: eardrum and vent.