Aves general characters

aves
general characters

1. Class:AVES -General characters B.Ashok Kumar Assistant Professor KRK Govt. Degree College Addanki-523201 9652929696 [email protected]

2. Class Aves 2

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 Smallest birds pics

5. The Origin of Birds 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 millenii Microraptor gui 5

6. Caudipteryx Feathered dinosaur Flightless Transitional fossil Dinosaur arms Dinosaur teeth Only front of upper jaw Bird feathers 6

7. Archaeopteryx Represents an animal 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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9. Microraptor gui 9

10. Characteristics of Birds Homeotherms /Endotherms/warm blooded 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 :

11. Internal Anatomy

12. Characteristics of Birds

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 bones fused Much lighter than reptile or mammal skull 16

17. Pygostyle – support for tail 17

18. Endoskeleton Sternum-keel/carina- attachment of flight muscles Ribs double headed Furcula - clavicle, interclavicle unite- ‘v’ Shaped(wish bone)

19. Flight muscles Powerful flight 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 Four chambered 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 Metanephric kidneys- three lobed Urinary bladder absent except in ostrich Uricotelic animals

25. Nervous system Two meninges- Duramater , Pia-Arachnoid membrane Cerebral hemispheres, optic lobes cerebellum are large Cranial nerves – 12 pairs

26. Sense organs Eyes-large-possesses nictitating 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 to 8 times keener than human vision Each eye moves indendtantly 27

28. Reproduction Copulatory organ absent 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 In the 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 The sperm 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 Many waterfowl 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 .

32. 32 Female

33. Male

34. The End 34