Frogs: Our Amphibian Friends
Basic Info
Frogs belong to the Amphibia class (Chordata phylum). The common Indian frog is called Rana tigrina. They’re special because they can live both on land 🏞️ and in freshwater 💧!
- ❄️ Cold-blooded: Their body temperature changes with the environment (also called poikilotherms)
- 🎨 Color changers: They camouflage by changing skin color to hide from enemies (mimicry)
- 😴 Seasonal sleepers:
• Summer sleep = Aestivation (hiding from heat)
• Winter sleep = Hibernation (hiding from cold)
Outside Features (Morphology)
- Skin: Smooth/slippery (due to mucus), always moist.
• Back = olive green with dark spots
• Belly = pale yellow - 🚰 Water absorption: Frogs drink through their skin!
- Body parts: Only head + trunk (no neck or tail)
- Eyes: Bulging, with a protective nictitating membrane
- Ears: Tympanum (visible membrane behind eyes)
- Legs:
• Front limbs: 4 fingers
• Back limbs: 5 toes with webbed feet (for swimming) - ♂️ Boys vs. Girls: Males have vocal sacs (for sound) and a thumb pad (copulatory pad)
Inside Parts (Anatomy)
Digestive System
- Short gut (because they eat meat 🍖)
- Food path: Mouth → Buccal cavity → Oesophagus → Stomach → Intestine → Rectum → Cloaca (exit!)
- Helper glands: Liver (makes bile) and Pancreas (makes digestive juice)
- 💡 Fun fact: Frogs catch food with their sticky, split-tongue (bilobed tongue)!
Breathing (Respiration)
- In water: Breathe through skin (cutaneous respiration)
- On land: Use mouth, skin, and lungs (pulmonary respiration)
- Lungs: Pink, sac-like structures in the chest
Blood & Circulation
- ❤️ Heart: 3-chambered (2 atria + 1 ventricle) with a protective pericardium
- Closed system: Blood flows in vessels
- Special blood highways:
• Hepatic portal system (liver ↔ intestine)
• Renal portal system (kidney ↔ body) - Blood parts: Plasma + RBCs (with hemoglobin) + WBCs + Platelets
Poop & Pee (Excretion)
- Main organs: Kidneys (bean-shaped), ureters, urinary bladder, cloaca
- 🧪 Waste type: Urea (frogs are ureotelic)
- 💡 Ureter job: Carries urine from kidneys to cloaca
Nervous System
- Brain parts: Forebrain, midbrain, hindbrain (in a bony brain box!)
- Nerves: 10 pairs of cranial nerves + spinal nerves
- 👂 Senses: Good eyes + ears (for balance too!), but no external ears
Baby-Making (Reproduction)
- ♂ Males: Two yellowish testes → Sperm travels through vasa efferentia → Urinogenital duct → Cloaca
- ♀ Females: Two ovaries → Eggs released via oviducts → Cloaca
- 🥚 Eggs: Females lay 2500-3000 eggs at once!
- Fertilization: External (in water)
- Babies: Eggs → Tadpoles → Adult frogs (metamorphosis)
Why Frogs Matter
- 🐜 Pest control: They eat insects → protect crops!
- 🌍 Eco-balance: Important in food chains
- 🍗 Food: Some people eat frog legs
NEET Quick Bites! 📚
- Frog Classification: Amphibia, poikilothermic, adaptations (camouflage/hibernation/aestivation)
- 3-Chambered Heart: Structure (2 atria + 1 ventricle) and circulation types (hepatic/renal portal systems)
- Respiration Dual Mode: Cutaneous (in water) vs. Pulmonary (on land)
- Ureotelic Excretion: Kidneys remove urea via ureters → cloaca
- External Fertilization: 2500-3000 eggs, tadpole metamorphosis
