MORPHOLOGY AND ANATOMY OF FROG

Frog

·         Kingdom- Animalia, Phylum-Chordata, Class- Amphibia, Order- Anura.

·         It generally lives in fresh water and land. Ex- Rana tigrina etc.

·         It is a cold blooded animal i.e. it doesn’t have constant body temperature.

·         It is mimicry in nature i.e. it has capacity to change their colour according to environment.

·         During peak summer and peak winter, it lives in the shelter region called summer sleep or aestivation and winter sleep or hibernation.

Morphology

·         Its body is made up of two parts head and trunk.

·         At head region interiorly mouth are present. Above it a pair of nostril is present and below these a pair of eyes is present. Eyes are covered with nictitating membrane which protects them in the water.

·         At either side of eyes a pair of tympanum (ear) is present.

·         It has fore limbs and hind limbs, which helps the frog in swimming, walking, leaping and burrowing.

·         It shows sexual dimorphism. i.e. both male and female are distinct characteristics  behaviour wise as well as have distinct sex organs for reproduction.

·         Character wise male is distinct from female with the presence of sound producing organ called vocal sacs and copulatory pad on the first digit of the fore limb.

·         Its skin is always moist due to presence of mucus.

·         Dorsally it is olive green with dark irregular spots while ventrally pile yellow in colour.

Fig- Morphology of  frog.

Anatomy

·         Its body is organ system level having digestive system, circulatory system, nervous system, excretory system and reproductive system.

Digestive System:-

·         It consists of alimentary canal and digestive glands. Its alimentary canal is short due to its carnivorous in nature.

·         Alimentary canal starts from mouth with two bilobed tongue> Pharynx> Oesophagus> Stomach> Intestine> Rectum> Outside through claeca.

·         Food captured and then goes to stomach. Here stomach digests the food particles with the help of HCL and gastric juice secreted by stomach wall.

·         Liver secrets bile enzyme and pancreas secrets pancreatic juice (Digestive Enzyme). These enzymes come to duodenum through a common duct and bile enzyme digest the fat as well as pancreatic juice digest carbohydrate and proteins.

·         Final digestion laterally takes place in the intestine through villi and microvilli.

Fig- Anatomical Structure of the Frog.

Respiratory System:-

·         Since, it is surface as well as land in habitat; it occurs cutaneous respiration in which skin act as respiratory organ and generally takes place in water.

·          It also occurs pulmonary respiration in which lungs act as respiratory organ and take place on the land. Here Skin, Buccal cavity also takes part in the respiration.

Circulatory System:-

·         The circulatory system of the frog is closed type. It consists of Blood vascular system + Lymphatic System.

·         Blood vascular system= Heart + Blood vessels + Blood. Lymphatic system= Lymph + Lymphatic channels + Lymph nodes.

·         Heart is three chambered as two atria and one ventricle.

·         Blood= Plasma + RBCs/Erythrocytes + WBCs/Leucocytes + Platelets.

·         Here veins collect bloods from different parts of the body to heart through venous system while arteries collect blood from heart and then distribute to all parts all parts of the body through arterial system.

Excretory System:- 

·         The frog has well developed excretory system which consists of a pair of kidneys, ureters, cloaca and urinary bladder which are ventrally situated on each posterior side.

·         Kidney> ureters (male- urenogenital duct, Female- Separately)> Cloaca.

·         The frog is ureothelic animal.

Nervous System:-

·         The nervous system of frog consists of neural system and some indocrine gland.

·         Some important indocrine glands are pituitary gland, thyroid, parathyroid, thymus, pineal body, pancreatic islets, adrenals and gonad.

·         Nervous System= Central Nervous System (Brain + Spinal Cord) + Peripheral Nervous System (Cranial Nerves & Spinal Nerve) + Autonomic Nervous System (Sympathetic & Parasymphetic).

·          Frog contains 10 pairs of cranial nerves.

·         Brain = For brain + Mid brain + Hind brain.

·         For brain= Olfactory lobes + Paired cerebral hemisphere + Unpaired diencephalon, Mid brain= Paired optic lobes, Hind brain= Cerebellum + Medulla oblongata.

Sensory System:-

 

·         Frog has different types of sense organ as for vision (eyes), Hearing (tympanum), Organ of touch (sensory papillae), Taste (taste buds) and for smell (nasal epithelium).

·         Eyes and Tympanum are well organised while others as cellular aggression.

Reproductive System:-

·          It is dioecious in nature. i.e. male and female reproductive organs are on the different bodies.

Male Reproductive System:-

·          It consists of a pair of testis (yellowish) situated at the upper part of kidneys with double fold peritoneum called mesorchium.

·          Each testis> 10-12 vasa efferentia>Kidney> Urenogenital duct> cloaca.

Female Reproductive System:-

·         It consists of a pair of ovaries which are situated near the kidneys. i.e. a oviduct arises from each ovary and directly open into cloaca nit connected with the kidneys.

·         A mature female can lay 2,500-3,000 ova at a time.

·         Fertilization is external with indirect development of tadpole larva.

Fig- Reproductive organ of Male and female.

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