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Aves general characters
Birds are feathered, warm-blooded vertebrates that are believed to have evolved from small feathered dinosaurs. They have light, pneumatic bones and powerful flight muscles attached to their sternum. Birds reproduce through internal fertilization, with males transferring sperm to females through a cloacal kiss and females later laying fertilized eggs.
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Introduction to birds, their characteristics, origin from dinosaurs, and notable species.An overview of bird anatomy including exoskeleton, endoskeleton, and adaptations for flight.
Description of birds' respiratory system, high metabolic rates, and the adaptation of air sacs for efficient oxygen intake.
Overview of the circulatory system (four-chambered heart) and details on the excretory system in birds.
Description of the nervous system, sensory capabilities particularly vision, and development of sense organs in birds.
Discussion on avian reproduction including fertilization methods, cloacal kiss, and egg development.
Conclusion of the presentation.
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Aves general characters
- 1. Class:AVES-General characters B.Ashok Kumar AssistantProfessor KRK Govt. Degree College Addanki-523201 9652929696 ashokkumarzoology@gmail.com
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- 3. Introduction • Includes birds •The feathered bipedal vertebrates • Homeotherms- successful in life • Origin- therapod dinosaurs-Jurassic period • Advanced over reptiles • T.H.Huxley- “Glorified Reptiles” • J.Z.Young- “The Masters of air” • Ornithology-Study of Birds • Largest bird- Ostrich(Struthio camelus) • Smallest bird- Bee Humming bird-Mellisuga helenae
- 4. • Largest • Smallestbirds pics
- 5. The Origin ofBirds • Most paleontologists agree that the common ancestor of all existing birds was a type of small, feathered dinosaur. • Recent fossil discoveries of feathered dinosaurs in China support this hypothesis. Caudipteryx zoui Sinornithosaurus milleniiMicroraptor gui 5
- 6. Caudipteryx • Feathered dinosaur •Flightless • Transitional fossil –Dinosaur arms –Dinosaur teeth • Only front of upper jaw –Bird feathers 6
- 7. Archaeopteryx • Represents ananimal that lived about 150 million years ago. • Unlike modern birds, Archaeopteryx had clawed forelimbs, teeth, and a long tail with vertebrae—all reptilian characteristics. • In fact, if the feathers had not been preserved in the fossil, Archaeopteryx probably would have been identified as a small dinosaur. 7
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- 10. Characteristics of Birds Homeotherms/Endotherms/ warmblooded Body-head, long neck, trunk & a short tail Boat shaped & streamlined Bipedal , forelimbs-wings, hind limbs-bears body weight Adopted- walking, running, swimming, percing etc. Skin-dry, only gland- Preen/Uropygeal-base of tail :
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- 13. Exoskeleton • Epidermal feathers •Scales on legs • Claws on toes • Rhamphotheca on beak
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- 15. Endoskeleton • Pneumatic bones-without bone marrow • Monocondylic skull • Two sacral vertebrae • Synsacrum- last thoracic, lumbar, sacral, few caudal vertebrae- fused with pelvic girdle for support to hind limbs • Pygostyle- posterior most caudal vertebrae fused- supports tail feathers
- 16. Skull • Most bonesfused • Much lighter than reptile or mammal skull 16
- 17. Pygostyle – supportfor tail 17
- 18. Endoskeleton • Sternum- keel/carina- attachment offlight muscles • Ribs double headed • Furcula- clavicle, interclavicle unite- ‘v’ Shaped(wish bone)
- 19. Flight muscles • Powerfulflight muscles • Pectoralis major-large-red- connected to lowerside of head of humerus & keel of sternum- downstroke (Depressor muscle) • Pectoralis minor-arise from sternum-connected to dorsal sideof humerus- upstroke(Elevator) • Coracobrachialis- connects corocoid & lowerside of head of humerus(depressor)
- 20. Digestive System • Edentate •Crop-Storage • Stomach-Proventriculus – Enzymes • Gizzard – Grind food • Cloaca- coprodeum, urodeum,& proctodeum – Waste – Reproduction – Bursa of Fabricius-blind sac with lymphoid tissue-proctodeum 20
- 21. Respiratory System • Lungs-spongy, alveoli absent • Nine air sacs-unpaired interclavicular, paired- cervical, anterior thoracic, posterior thoracic, & abdominal • Fresh air always moving inside • Trachea large & coiled • Syrinx-junction of trachea & bronchi- sound producing organ 21
- 22. High Metabolic Rate •Birds have a system of branching air sacs that function with their lungs in respiration. • The system of air sacs supplies the high levels of oxygen needed to support a high rate of metabolism for the hard-working flight muscles. • This high metabolic activity also provides heat for endothermy. 22
- 23. Circulatory System • Fourchambered heart- two atria & two ventricles • Sinus venosus & truncus arteriosus absent • Two aortic arches- right systemic arch & pulmonary arch- present • Renal portal system- reduced • Erythrocytes- oval & Nucleated • Complete double circulation 23
- 24. Excretory system • Metanephrickidneys- three lobed • Urinary bladder absent except in ostrich • Uricotelic animals
- 25. Nervous system • Twomeninges- Duramater, Pia-Arachnoid membrane • Cerebral hemispheres, optic lobes cerebellum are large • Cranial nerves – 12 pairs
- 26. Sense organs • Eyes-large-possessesnictitating membrane • Sclerotic plates in sclerotic layer- maintain shape of the eye • Comb shaped pecten- projects into vitreous humour- probably nourishes, removes wastes • External ear openings present, middle ear with single ossicle- columella auris, cochlea with organ of corti in internal ear • Olfactory sense is poor except in kiwi
- 27. Vision • Up to8 times keener than human vision • Each eye moves indendtantly 27
- 28. Reproduction • Copulatory organabsent except decks, geese, swans, flightless birds • In female- right ovary, right oviduct- rudimentary • Fertilisation internal • Oviparous- megalecithal, cleidoic eggs • Meroblastic cleavage • Four extra embryonic membranes- appear during development
- 29. Avian Reproduction • Inthe males of species without a phallus, sperm is stored within the proctodeum compartment within the cloaca prior to copulation. • During copulation, the female moves her tail to the side and the male either mounts the female from behind or moves very close to her. • He moves the opening of his cloaca, or vent, close to hers, so that the sperm can enter the female's cloaca, in what is referred to as a cloacal kiss. This can happen very fast, sometimes in less than one second.
- 30. Avian Reproduction • Thesperm is stored in the female's cloaca for anywhere from a week to a year, depending on the species of bird. • Then, one by one, eggs will descend from the female's ovaries and become fertilized by the male's sperm, before being subsequently laid by the female. • The eggs will then continue their development in the nest.
- 31. Avian Reproduction • Manywaterfowl and some other birds, such as the ostrich and turkey, do possess a phallus. • Except during copulation, it is hidden within the proctodeum compartment within the cloaca, just inside the vent. • The avian phallus differs from the mammalian penis in several ways, most importantly in that it is purely a copulatory organ and is not used for dispelling urine.
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