Sunday, 17 November 2019

Morphology and Anatomy of Frog


Morphology and Anatomy of Frog poster

Frog Morphology

Dorsal view of the frog diagram


Fig.: Dorsal view of the frog


Article gives Frog morphology & anatomy structure like brow spot, dorsolateral dermal plicae, its dorsal view & many more about internal & external.

The body of a frog has pointed anteriorly and rounded posteriorly. It is slightly flattened dorsoventrally, streamlined to swim through the water and divisible into head and trunk without neck and tail.



The skin of the frog is thin, moist, smooth, slimy and green colored with black or brown spots dorsally and lighter pale yellow ventrally. There are no scales or any other hard exoskeleton parts.

The skin of back has dorsolateral folds or thickenings called dermal plica.

Head is roughly triangular with a short blunt anterior snout terminating in a large transverse mouth. It bears external nares or nostrils, eyes, brow spot frog and eardrums on the upper side.

Frogs have two large and protruding eyes, having an almost immovable upper eyelid and a thin semitransparent and freely movable lower eyelid. From lower eyelid arises a nictitating membrane that protects eyes during swimming.

Vocal sacs act as resonators to intensify the sound of croaking during the breeding season.

The trunk consists of thorax, abdomen and a pair of forelimb and hind limb.

Frog shows sexual dimorphism as male frog possesses developed vocal sacs and nuptial pad during the breeding season and their body is somewhat slender and darker in color than a female frog.

Anatomy of Frog

Circulatory System of Frog


Circulatory System of Frog diagram

Fig.: Internal structure of heart of frog (ventral view)

The circulatory system of the frog is closed and includes the heart, arterial system, the venous system, blood, and lymphatic system.

The heart is three-chambered made up of two anterior atria or auricles and a single posterior ventricle. Two additional chambers are sinus venous and Truncus Arteriosus.

The two auricles, right (larger) and left, are completely separated from each other by inter-auricular septum. Both auricles open into single ventricle by a common large auriculo-ventricular aperture guarded by two pairs of auriculo-ventricular valves.

The inner surface of the ventricle has irregular ridges called columnar carnage or trabeculae, with depressions called fissures.

Digestive System of Frog


Digestive System of Frog diagram

The digestive system mainly consists of the alimentary canal and its associated glands.

The mouth leads into a buccopharyngeal cavity that opens into the esophagus through the gullet.

The stomach is situated behind the esophagus and divisible into the cardiac stomach and pyloric stomach.

The small intestine is divisible into an anterior duodenum and posterior ileum. Digestion of food and absorption of digested food occurs in the small intestine.
Ileum leads to the rectum or large intestine. The rectum opens into the cloaca through the anus.

Digestive glands of frog include liver, pancreas, gastric glands and intestinal glands.

Respiratory System of Frog

Lungs of frog diagram

Fig.: Lungs of frog

Adult frog respires by three different types of respiration:

Cutaneous respiration: It occurs through the highly vascular skin of frog in water or land.

Buccopharyngeal respiration: It occurs on land or during partial immersion in water via the mucous epithelial lining of the buccopharyngeal cavity.

Pulmonary respiration: It is less frequent and takes place through the lungs in the adult frog when the frog is outside the water.

Nervous System of Frog

Dorsal view of the brain of the frog diagram

Fig.: Dorsal view of the brain of the frog

It is highly developed and comprises of:

 The central nervous system (CNS) includes the brain and spinal cord. The brain is covered by two meninges; dura mater (outer) and pia-arachnoid (inner). The brain is divisible into three parts: Forebrain, midbrain, and hindbrain. The spinal cord is located in the vertebral column and joins the medulla oblongata via foramen magnum of the cranium (braincase).

 The peripheral nervous system (PNS) includes 10 pairs of cranial nerves than 9 pairs of spinal nerves. Rarely 10 (paired or unpaired) spinal nerve is found.

The autonomic nervous system is made up of sympathetic and parasympathetic nerves that control and coordinates the involuntary activities of the visceral organs.

Five types of sense organs are skin (tango receptor), taste buds (Gustatoreceptor), nasal chambers (autoreceptor), eyes (photoreceptor) and ears (state acoustic organs).

''Urinogenital System of Frog"


Alimentary canal of frog diagram

Fig.: Alimentary canal (except buccopharyngeal cavity) of frog

system of the male frog diagram

Fig.: the urinogenital system of the male frog


system of the female frog diagram

Fig.: the urinogenital system of the female frog

In frogs, the excretory and reproductive systems are closely associated, hence they are together called the urinogenital system.

The excretory system comprises of kidneys, ureters in females, urinogenital ducts in males, cloaca and urinary bladder. Kidneys are the chief excretory organs that are made up of a large number of uriniferous tubules or nephrons.

From the kidneys, arise ureter in females and urinogenital duct in males.

Cloaca receives fecal matter, genital products and urine (from the kidney). centrally it is attached to the urinary bladder.

In males, near each kidney, there is a cylindrical testis from which several thin Vasa differential, connecting the testes to kidneys on each side. The Vasa Efferentia runs transversely through Mesorchium and opens into the Bidder’s canal which in turn opens into the ureter. Histologically, each testis is a compact mass of Seminiferous tubules, the epithelial lining of which produces sperms. The sperms when mature are dropped into the Lumen to pass into the ureter through Vasa Efferentia and Bidder’s canal.

Females have two ovaries where ova are produced by ovarian follicles. On each side of an ovary is an oviduct which starts Posteriorly and forms uterus, which opens into the cloaca. During the breeding, season ova are released into the coelom and then they reach the ovarian funnels from where they pass to the visas, cloaca and then outside.

Egg of frog is isolecithal.

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