This document provides information on the classification and features of the frog Rana tigrina. It discusses the frog's ability to live both on land and in water, its poikilothermic nature, camouflage abilities, and habit of hibernating or aestivating during extreme temperatures. The document also summarizes the frog's morphology, digestive, respiratory, circulatory, excretory, nervous, and reproductive systems.

1. Hi there!!
myself Rana tigrina

3. Kingdom Animalia
Phylum Chordata
Sub Phylum Vertebrata
Section Gnathostomata
Superclass Tetrapoda
Class Amphibia
Order Anura
Family Ranidae
Genus Rana
Species tigrina
FROG : Classification

4. FROG : Features
1. Frogs can live both on land and in freshwater and belong to
class Amphibia of phylum Chordata. The most common species
of frog found in India is Rana tigrina.
2. They do not have constant body temperature i.e., their body
temperature varies with the temperature of the environment.
Such animals are called cold blooded or poikilotherms.
3. You might have also noticed changes in the colour of the frogs
while they are in grasses and on dry land. They have the ability
to change the colour to hide them from their enemies
(camouflage). This protective coloration is called mimicry.
4. You may also know that the frogs are not seen during peak
summer and winter. During this period they take shelter in deep
burrows to protect them from extreme heat and cold. This is
called as summer sleep (aestivation) and winter sleep
(hibernation).

5. FROG : Morphology
1. The skin is smooth and slippery due to the presence of mucus.
The skin is always maintained in a moist condition.
2. The colour of dorsal side of body is generally olive green with
dark irregular spots. On the ventral side the skin is uniformly pale
yellow.
3. The frog never drinks water but absorb it through the skin.
4. Body of a frog is divisible into head and trunk. A neck and tail are
absent in a mature frog.
5. Above the mouth, a pair of nostrils is present.
6. Eyes are bulged and covered by a nictitating membrane that
protects them while in water.
7. On either side of eyes a membranous tympanum (ear) receives
sound signals. The forelimbs and hind limbs help in swimming,
walking, leaping and burrowing. The hind limbs end in five digits
and they are larger and muscular than fore limbs that end in four
digits. Feet have webbed digits that help in swimming
8. Frogs exhibit sexual dimorphism. Male frogs can be distinguished
by the presence of sound producing vocal sacs and also a
copulatory pad(nuptial pad) on the first digit of the fore limbs
for clasping the female

6. FROG : Digestive System
The digestive system consists of alimentary canal and digestive glands. The
alimentary canal is short because frogs are carnivores and hence the length of
intestine is reduced but complete i.e from mouth to cloaca
ALIMENTARY CANAL
1. Mouth : The mouth opens into the buccal cavity that leads to the oesophagus
through pharynx.
2. Oesophagus : Oesophagus is a short (due to absence of neck) tube that opens
into the stomach.
3. Stomach :
a) Lies on the left side of the body cavity, made up of an anterior
cardiac stomach and a posterior Pyloric stomach
b) Multicellular gastric gland : pepsinogen
Unicellular oxyntic gland : HCl
4. Intestine : Longest part of the alimentary canal and divided into the
duodenum, ileum and rectum (also known as large intestine)
DIGESTIVE GLANDS
1. Liver secretes bile that is stored in the gall bladder
2. Pancreas, a digestive gland produces pancreatic juice containing digestive enzymes.

7. FROG : Digestive System
1. The frog feeds on insects, worms, molluscs etc.
2. Food is captured by the bilobed tongue and swallowed whole.
3. Digestion of food takes place by the action of HCl and gastric juices
secreted from the walls of the stomach.
4. Partially digested food called chyme is passed from stomach to the first
part of the intestine, the duodenum.
5. The duodenum receives bile from gall bladder and pancreatic juices from
the pancreas through a common bile duct.
6. Bile emulsifies fat and pancreatic juices digest carbohydrates and
proteins.
7. Final digestion takes place in the intestine. Digested food is absorbed by
the numerous finger-like folds in the inner wall of intestine called villi and
microvilli.
8. The undigested solid waste moves into the rectum and passes out
through cloaca.

8. FROG : Respiratory System
1. Frogs respire on land and in the water by two
different methods.
2. a) In water, skin acts as aquatic respiratory organ
(cutaneous respiration). Dissolved oxygen in the
water is exchanged through the skin by diffusion.
b)On land, the buccal cavity, skin and lungs act as
the respiratory organs. The respiration by
lungs is called pulmonary respiration.
3) The lungs are a pair of elongated, pink coloured
sac-like structures present in the upper part of the
trunk region (thorax).
Air enters through the nostrils into the buccal cavity
and then to lungs. During aestivation and hibernation
gaseous exchange takes place through skin.

9. FROG : Blood Vascular System

10. FROG : Blood Vascular System
1. The vascular system of frog is well-developed closed type, involves heart, blood vessels
and blood
2. Frogs have a lymphatic system also which is mad up of lymph, lymph channels and
lymph nodes
3. Heart is a muscular structure situated in the upper part of the body cavity. It has three
chambers, two atria and one ventricle and is covered by a membrane called pericardium.
4. A triangular structure called sinus venosus joins the right atrium. It receives blood
through the major veins called vena cava.
5. The ventricle opens into a sac like conus arteriosus on the ventral side of the heart.
6. The blood from the heart is carried to all parts of the body by the arteries (arterial
system). The veins collect blood from different parts of body to the heart and form the
venous system.
7. Special venous connection between liver and intestine as well as the kidney and lower
parts of the body are present in frogs. The former is called hepatic portal system and
the latter is called renal portal system.
8. The blood is composed of plasma and cells.
9. The blood cells are RBC (red blood cells) or erythrocytes, WBC (white blood cells) or
leucocytes and platelets.
10. RBC’s are nucleated, oval, biconvex and contain red coloured pigment namely
haemoglobin.
11. The lymph is different from blood. It lacks few proteins and RBCs.
12. The blood carries nutrients, gases and water to the respective sites during the
circulation. The circulation of blood is achieved by the pumping action of the muscular
heart.

11. FROG : Excretory System
1. The elimination of nitrogenous wastes is carried out by a well developed
excretory system.
2. The excretory system consists of a pair of kidneys, ureters, cloaca and
urinary bladder.
3. Kidneys are compact, dark red and bean like structures situated a little
posteriorly in the body cavity on both sides of vertebral column.
4. Each kidney is composed of several structural and functional units called
uriniferous tubules or nephrons.
5. Two ureters emerge from the kidneys in the male frogs. The ureters act as
urinogenital duct which opens into the cloaca.
6. In females the ureters and oviduct open seperately in the cloaca.
7. The thin-walled urinary bladder is present ventral to the rectum which also
opens in the cloaca.
8. The frog excretes urea and thus is a ureotelic animal.
9. Excretory wastes are carried by blood into the kidney where it is separated
and excreted.

12. FROG : Control & Coordination
The system for control and coordination is highly evolved in the frog. It includes both neural system and endocrine glands.
A. Endocrine System :
1. The chemical coordination of various organs of the body is achieved by hormones which are secreted by the endocrine
glands.
2. The prominent endocrine glands found in frog are pituitary, thyroid, parathyroid, thymus, pineal body, pancreatic islets,
adrenals and gonads
B. Nervous System :
1. The nervous system is organised into a
central nervous system (brain and spinal cord),
peripheral nervous system (cranial and spinal nerves) and
autonomic nervous system (sympathetic and parasympathetic).

13. FROG : Control & Coordination
Central Nervous System
1. Brain is enclosed in a bony structure called brain box (cranium).
2. The brain is divided into fore-brain, mid-brain and hind-brain.
3. Forebrain includes olfactory lobes, paired cerebral hemispheres and
unpaired diencephalon.
4. The Midbrain is characterised by a pair of optic lobes.
5. Hind-brain consists of cerebellum and medulla oblongata.
6. The medulla oblongata passes out through the foramen magnum and
continues into spinal cord, which is enclosed in the vertebral column
Peripheral Nervous System
1. Cranial Nerves : 10 pairs of cranial nerves originating from the brain of frog
2. Spinal Nerves : 10 pairs of spinal nerves originating from the spinal cord of
frog
Autonomic Nervous System
It is a system of nerve fibres and ganglia which controls and coordinates the
involuntary activities of the visceral organs.

14. FROG : Control & Coordination
Sense Organs
Frog has different types of sense organs,
namely organs of touch (sensory papillae), taste (taste buds), smell (nasal epithelium), vision (eyes) and hearing (tympanum
with internal ears).
Eyes and internal ears are well-organised structures and the rest are cellular aggregations around nerve endings.
Eyes in a frog are a pair of spherical structures situated in the orbit in skull.
These are simple eyes (possessing only one unit).
External ear is absent in frogs and only tympanum can be seen externally.
The ear is an organ of hearing as well as balancing (equilibrium).

15. FROG : Reproductive System
MALE REPRODUCTIVE SYSTEM
It consists of 2 testes (attached to the kidneys), several vasa effrentia and 2
urinogenital ducts (copulatory organs are lacking)
1. TESTES :
- Elongated ovoid light yellowed body attached to the upper part of the kidney
by a double fold of peritoneum called mesorchium.
- Each testes is a compact mass of coiled seminiferous tubules.
2. VASA EFFERNTIA :
- 10-12 fine tubules that connect the testes to the kidney.
- They enter the kidneys on their side and open into Bidder’s canal.
- Finally it communicates with the urinogenital duct
3. URINOGENITAL DUCT :
- In the male it is both a urinary as well as a sperm duct.
- Each duct runs posteriorly and opens into the cloaca
4. CLOACA :
- The cloaca is a small, median chamber that is used to pass faecal matter, urine
and sperms to the exterior.

16. FROG : Reproductive System
FEMALE REPRODUCTIVE SYSTEM
It consists of a pair of Ovaries and Oviducts
1. OVARIES :
- Paired, irregular shaped lobulated structures, located near the kidneys but no
connection to the kidneys.
- Each ovary contains innumerable dark round ova in different stages of
development.
- When ripe, the ova are shed into the body cavity from where they move into
the oviducts
2. OVIDUCTS :
- Paired long white glandular coiled tubes lying on either side of the body cavity.
- The posterior ends of the ducts are broad called ovisacs which open dorsally
into the cloaca.
- Eggs are temporarily stored in the ovisacs.
- A mature female frog can lay 2500 to 3000 ova at a time