Characteristic of Birds

[b]IEPJ C Betty Lo Jan. 22
Science Assignment—Birds

Have you ever hear beautiful voices that come from the trees when you are walking in a park in a lovely morning? When you look up, you will see a mother who is feeding her babies. Sometimes, when you are walking on the roads, some smelly white disgusting liquid falls down from the sky and hit right on to your face all of a sudden. It’s the animals that loved by the children and hated by the farmers—the birds.
Here is information about birds.

Birds are vertebrates that lay eggs. They are bipedal that are endoderm. Modern birds are characterized by feathers, a beak with no teeth, the laying of hard-shelled eggs. A bird’s nervous system is developed. Compared to reptiles of the same body weight, a bird’s brain is 6 or 10 times larger than reptile’s. The cranium, (the brain case) is very thin helping the birds to fly. The olfactory lobes (sense of smell) are very small. The cerebrum, cerebellum, medulla and optic lobes are well developed. They have four-chambered heart. The respiratory system contains air sacs in addition to lungs and airways. Because birds have no teeth, they cannot chew their food. Birds usually swallow their food whole. The crop, an enlargement at the base of the esophagus, stores the food and moistens it in preparation for digestion. The second division of the stomach, the gizzard, then receives the food. Birds have light-weight but strong skeleton and some bones are hollow. The also have fewer bones than mammals and reptiles. The hollow bones are supported by struts. Believe it or not a rabbit’s bones weigh about the same as a chicken’s bones! Though a bird’s bones are lightweight, the total skeleton weight is the same as a mammal of the same weight.


Reference:
1. www.people.eku.edu/ritchisong/birddigestion.html