Class – Aves

.GENERAL CHARACTERISTICS:

• Feath­ers: The most dis­tinc­tive fea­ture, cov­er­ing most of the body.
• Flight: Most birds are capa­ble of flight, with some excep­tions (e.g., ostrich).
• EXTERNAL FEATURES:
• Beak: Present, vary­ing in shape and size depend­ing on diet.
• Fore­limbs: Mod­i­fied into wings for flight.
• Hind limbs: Cov­ered with scales, adapt­ed for var­i­ous func­tions like walk­ing, swim­ming, or perch­ing (clasp­ing).
• Skin: Dry, lack­ing glands except for the uropy­gial (oil) gland at the base of the tail.
• INTERNAL FEATURES:
• Endoskele­ton: Ful­ly ossi­fied (bony), pro­vid­ing a strong and light­weight frame­work.
• Bones: Long bones are hol­low and con­tain air cav­i­ties (pneu­mat­ic bones), reduc­ing weight for flight.
• DIGESTIVE SYSTEM:Con­tains addi­tion­al cham­bers:
• Crop: Stores food before diges­tion.
• Giz­zard: Grinds food, often with the help of ingest­ed grit.
• CIRCULATORY SYSTEM: Heart.
• Com­plete­ly four-cham­bered, ensur­ing effi­cient oxy­gen sup­ply.
• Warm-blood­ed (homoio­ther­mous): Able to main­tain a con­stant body tem­per­a­ture regard­less of the exter­nal envi­ron­ment.
• RESPIRATORY SYSTEM:
• Lungs: Pri­ma­ry organs for gas exchange.
• Air sacs: Con­nect­ed to lungs, they extend into var­i­ous body cav­i­ties and even bones, aid­ing in res­pi­ra­tion and reduc­ing body weight.
• They also facil­i­tate a con­tin­u­ous flow of air through the lungs.
• REPRODUCTION AND DEVELOPMENT:
• Sex­es: Sep­a­rate (dioe­cious).
• Fer­til­iza­tion: Inter­nal.
• Repro­duc­tion: Oviparous (lay eggs).Development: Direct (no lar­val stage).
• Exam­ples:Corvus (Crow), Colum­ba (Pigeon), Psit­tac­u­la (Par­rot), Struthio (Ostrich), Pavo (Pea­cock), Apten­odytes (Pen­guin), Neophron (Vul­ture)