In which of the following are air sacs connected to the lungs?
(1) Neophron
(2) Testudo
(3) Ornithorhynchus
(4) Chelone

Solution:(1) Neophron

Class – Aves

The characteristic features of Aves (birds) are the presence of feathers

and most of them can fly except flightless birds (e.g., Ostrich). They possess

beak (Figure 4.23). The forelimbs are modified into wings. The hind limbs

generally have scales and are modified for walking, swimming or clasping

the tree branches. Skin is dry without glands except the oil gland at the

base of the tail. Endoskeleton is fully ossified (bony) and the long bones

are hollow with air cavities (pneumatic). The digestive tract of birds has

additional chambers, the crop and gizzard. Heart is completely fourchambered.

They are warm-blooded (homoiothermous) animals, i.e.,

they are able to maintain a constant body temperature. Respiration is by

lungs. Air sacs connected to lungs supplement respiration. Sexes are

separate. Fertilisation is internal. They are oviparous and development is

direct.

Examples : Corvus (Crow), Columba (Pigeon), Psittacula (Parrot), Struthio

(Ostrich), Pavo (Peacock), Aptenodytes (Penguin), Neophron (Vulture).