Frog

Phylum : Chordata

Sub phylum : Vertebrata

Section : Gnathostomata

Class : Amphibian

Sub class : Anura

Order : Phaneroglossa

Family : Ranidac                                               

Ginus : Rana

Species : Ligrina

• Frog is amphibian i.e. it can live both on land and in freshwater.
• Frog are cold blooded animals i.e. their temp varies with temperature varies temperature of environment.
• They have property of camouflage i.e. to change body is colour acc. to environment 0 this protective is called mimicry.
• Aestivation: summer sleep

Hibernation : winter sleep

Frogs are not run during peak summer and winter i.e. they undergoes aestivation or hibernation.

Morphology :-

• Due to presence of mucus, skin of frog is smooth and slippery.
• On dorsal side, colour of skin is olive green with dark irregular spots.
• On ventral side, colour of skin is pale yellow.
• Body of frog is consist of head and trunk.
• A pair of nostrils is present above mouth.
• Nictitating membrane covers eye which protects eye while in water.
• The sound signals is received by membranous tympanum present on either side of eyes.
• The hind limbs and fore limbs helps in swimming, walking, leaping and burrowing.
• The hind limbs in five digits and they are layer and muscular than forelimbs, that end in four digits.
• Webbed futs are present which help in swimming.
• Female frogs are differ from. Male frogs in presence of sound producing vocal sacs and copulatory pad on first digit of forelimbs.

Anatomy :-

Digestive system :- alimentary canal + Digestive glands.

• Frog is a carnivorous animal so there is alimentary canal and length of intestine is also short.
• Through pharynx, Buccal cavity leads to oesophagus.
• Oesophagus leads to stomach continues with intestine rectum, and finding opens outside the cloacae.
• Gall bladder stores the bile, secreted by liver.
• Pancreatic juice is secreted by pancreas.
• HCl and gastric juice helps in food digestion, secreted from walls of stomach.
• After digestion in stomach, the chyme is passed to the duodenum of small intestine.
• Carbohydrates and protein are digested bile and pancreatic juice secreted by lives and pancreas respectively in duodenum.
• Pancreatic juices digest carbohydrates and proteins.
• Bile emulsifies fat.
• Digested food is absorbed by numerous finger –like- folds in inner wall of intestine called mirouvilli and uilli.
• The indigested food is expelled through cloaca .

Respiratory system:-

• In water, frogs respire skin. This kind of respiration is called cutaneous respiration through diffusion, gaseous exchange can take place.
• On land, buccal cavity, skin and lungs act as respiratory organ i.e. pulmonary respiration.
• During aestivation and hibernation, cutaneous respiration takes place.

Circulatory system:-

• Closed-type circulatory system is found in frogs.
• It inverses :- heart, blood vessels which consist of lymph nodes, lymph channels and lymph.
• Heart situated in the upper part of body cavity.
• Heart is covered by membrane called pericardium.
• It has three chambers, two atria and one ventride.
• Right atrium recur blood through vena cava.
• On the ventral side of the heart, ventricle opens into sac like comes arteriosus.
• Arteries carry the blood from left ventricle to all parts of body is called arterial system.
• Veins carry the blood from all parts of body to right atrium of heart forms venous system.
• Venous connection b/w kidney is called renal portal system.

Composition of Blood :-

Blood is composed of plasma and cells.

Blood cells are :- RBC,WBC and platelets.

Haemoglobin is pigment present in blood which gives red colour to blood. Blood carries nutrients, gases and water.

Lymph :- is lack of RBC and few proteins.

Excretory system :-

• Mode of excretion : Ureotelic.
• A pair of kidney work as excretory and osmougulatory organ in frog, attached to back muscles.
• Kidney is made up of numerous functional unit called nephorms.
• These neurons separate water and urea from blood and pass it to urinary bladder via ureters and doaica.

Control and co-ordination :-

Neural system :-                        

• Central Nervous system (Brain and spinal cord.)
• Peripheral nervous system (cranial and spinal nerves)
• Autonomic nervous system (sympathetic and parasy empathetic )

• Brain is enclosed in the brain box (cranium ) 
• There are 10 pairs of cranial nerves arising from brain.

Parts of Brain:-

• Forebrain :- it includes olfactory lobs, paired cerebral hemispheres and unpaired cliencephalon.
• Mid-brain :- it has pair of optic lobes.
• Hind brain :- brain it consists of cerebellum and medulla oblongata. Medulla oblongata passes through the foramenen mag nun and continuous into spinal cord, enclosed in vertebral column.

Sense organs:-

Organs of touch :- sensory papillae

Organs of taste :- taste buds,

Organs of smell :- nasal Epithelium

Organs of vision :- eyes

Organs of hearing :- Tympanum with internal ears  

• Eyes are situated in orbits skull.
• External ear is absent in frogs and only tympanum can be seen externally. It also maintains body equilibrium.

Endocrine system :-

Consist of endocrine glands.

• These glands discharge their secretions that is into blood.
• Various glands in frog are :- pituitary, pineal, thyroid, parathyroid thymus, pancreas, adrenals and gonads.

Reproductive system:-

Male reproductive system :-

• Yellow coloured rod-like structure is joined to anterior part of kidney called testes.
• About 10-12 fine tubules, Vera efferent a arises from each testes and open into bidder’s canal.
• This Bidder’s canal communicates with the ureter.
• ureter is called urinogenital  duct in frog because it carrier lerine as well as sperms.
• ureter  opens into small median chamber i.e. cloaca,

Female reproductive system:-

• it include a pair of ovaries.
• This pair of ovaries is situated near kidney but no functional connection with it.
• Ovaries give rise to oviducts which opens into cloaca separately

Fertilization :-

• Fertilization egg grows into tadpole.

Tadpole undergoes metamorphoses to form adult.