Rana tigrina(Frog)-Priya jha PGT Biology

The world’s tropical forests house a spectacular array of frogs. In fact, although found almost everywhere on Earth, frogs are at their most diverse in tropical regions—places like the Amazon rainforest and the forests of Equatorial Africa. The following are seven amazing types of frogs found exclusively in those environments, which typically are hot, wet, and densely vegetated—perfect for creatures specially adapted to both aquatic and terrestrial habitats.

1. STRUCTURAL ORGANISATION IN ANIMALS PRIYA JHA PGT BIOLOGY FROG: Rana tigrina

2. ORGAN AND ORGAN SYSTEM The structural organisation in animals or any other lifeform is the same at the fundamental level. Or in other words, all life currently living on earth are made up of cells. And when cells get together, they form tissues. Tissues, in turn, form organs and organ systems. Cells   → Tissues   → Organs →   Organ system

3. Pokilotherma Shows camouflage and mimicry Show Hibernation and Aestivation

4. Morphology of Frogs The skin is moist, smooth, and slippery due to the presence of mucus. Dorsally, the body is generally olive green with dark irregular spots. Ventrally, the skin is uniformly pale yellow. The frog never drinks water but absorbs it through the skin. Body is divisible into head and trunk. A neck and tail are absent. A pair of nostrils is present above the mouth.

5. Eyes are bulged and covered by a nictitating membrane that protects them while in water. Membranous tympanum or ear (on either side of eyes) receives sound signals. The four webbed digits of forelimbs and five webbed digits hind limbs help in swimming, walking, leaping, and burrowing. Feet have webbed digits that help in swimming Sexual Dimorphism: Vocal sacs present only in male which acts as resonators,nuptil pad(only in male frog)

6. Anatomy The body plan of frogs consists of well-developed structures which help them in their physiological activities. The body cavity accommodates all the organ systems such as digestive, respiratory, circulatory, excretory, nervous and reproductive systems, whose functions are almost similar to human body systems.

7. Digestive system Having Alimentary Canal, Digestive glands Frogs are carnivore so length of Alimentary Canal is short Bilobed tounge is attached to the front of the frog's mouth, allowing it to launch almost the entire tongue out of its mouth . It launches incredibly fast. A frog can shoot out its tongue, capture an insect, and pull it back into its mouth within The alimentary canal begins at the mouth (buccal or oral cavity), passes through the pharynx, oesophagus or food pipe, stomach, small intestines, large intestines, rectum and finally ending at the cloaca.

8. Respiratory system The amphibian has two modes of respiration – cutaneous respiration and pulmonary respiration. In an aquatic ecosystem, the skin is the respiratory organs where the diffusion of dissolved oxygen takes place. This is called cutaneous respiration. While on land, they use both skin and lungs for respiration. During pulmonary respiration, air entering through nostrils passes to the lungs via the buccal cavity. Buccopharyngeal Respiration: gaseous exchange through membrane of Buccal cavity and phyranx But during summer sleep(aestivation) and winter sleep(hibernation), they use only skin for respiration.

9. Circulatory system Closed Vascular system(all vertebrates) I) Heart: (a)Muscular(myogenic-pacemaker made up of heart muscles) (b)3 Chambered( two atria and one ventricle) , ( c)Covered by Pericadrium II) Blood Vessels (a) Artery (b) Veins ( c) Capillaries III) Blood (a) Nucleated RBC,(RBC contain Hemoglobin),( Erythrocytes are nucleated and contain red coloured pigment namely haemoglobin ) (b)WBC(Leukocytes), (c)Platelets IV)Lymphatic :No RBC, No Proteins V) Incomplete Double circulation

10. A triangular sinus venosus joins the right atrium . It receives blood through vena cava. The ventricle opens into conus arteriosus on the ventral side of the heart. Arteries carry the blood from the heart to all parts of the body (arterial system) and veins collect blood from different body parts to the heart (venous system). Hepatic portal system is present between liver and intestine, whereas renal portal system is present between the kidney and lower parts of the body The blood carries nutrients, gases, and water to the respective sites during the circulation.

11. Excretory system The frog is a ureotelic animal whose major excretory product is urea. (Tadpole-Ammonia ) They have a distinguishable excretory system composed of a pair of kidneys, ureters, cloaca and urinary bladder. The kidneys have the structural unit called nephron which filters the blood and excretes out the waste.

12. Coordination system The nervous system and the endocrine system together perform the control and coordination in frogs. The endocrine system is composed of the endocrine glands such as pituitary, thyroid, parathyroid, thymus, pineal body, pancreatic islets, adrenals, and gonads. The secretions of these glands called hormones are responsible for metamorphism and other regulatory functions.

13. The nervous system is divided into CNS and PNS. The brain is distinguished as forebrain, midbrain, and hindbrain which control different parts of the body. The brain is enclosed in the cranium and the vertebral column protects the spinal cord.

14. Male Reproductive System It consists of the testis, vasa deferentia , seminal vesicle and urinogenital ducts. Testis – Male frogs have pairs of testes that are pale in colour and oval in shape. The testis is covered by the peritoneum fixed to the wall of the kidney. Each testis has coiled filaments called seminiferous tubules that are connected by connective tissue. Each tubule is covered by a membrane. The seminiferous tubules produce spermatozoa Vasa deferentia – A combination of 10 to 12 ducts arise from the testes and are covered by the connective tissue. A group of ducts is called rete testis Seminal vesicle – Seminal vesicle is the portion where sperms are stored until copulation takes place. It consists of fructose that gives nutrients to the sperms Urino genital ducts – This is also called the ureter. Here, sperm is passed out along with urine Sperm formation – The formation of the stem is known as spermatogenesis.

15. Female Reproductive System It consists of a pair of ovaries, oviduct, oviduct funnel, middle region and uterus. Ovary – A pair of dark- coloured organs are surrounded by a membrane called mesovarium. The ovary is filled with eggs. Ova is also called an egg. During ovulation, ova come out of the abdomen Oviduct – The oviduct is a slender and elongated duct that connects to the kidneys Oviduct funnel – From the oviduct, a wide opening is situated near the lungs. This broad opening is also called ostium Uterus – It is the thin-walled structure that appears near the cloaca. After ovulation, the egg passes from the ovary with a fluid called the coelomic fluid. The ova are covered by a protein called albumin and reach into the uterus Egg formation – The maturation of the egg requires a few steps: the multiplication phase, the growth phase and the maturation phase

16. Reproductive system Both male and female frogs have their own reproductive system where gametes for reproduction are produced. The cloaca is a common pathway for excretion and reproduction. At a time, 2500 to 3000 eggs are laid which are fertilized externally. Fertilisation is external and takes place in water. Development involves a larval stage called tadpole. Tadpole undergoes metamorphosis to form the adult.

17. Frogs show external fertilisation that occurs in water. This is followed by the development into tadpole, which is the larval stage. Finally, an adult is formed by the metamorphosis of the tadpole

18. Interaction with Mankind They eat insects and protect the crop. They maintain ecological balance as they serve as an important link of food chain and food web in the ecosystem. In some countries, the muscular legs of frog are used as food.