How does this phylum fit into the evolutionary tree (cladogram)? 13
Birds (Aves) are a class of Dinosauria. They have a Most Recent Common Ancestor with Reptiles – clade Sauria 251 MYA; its early members were probably small lizard-like creatures.
Their Most Recent Ancestor with Humans is probably around 350 MYA when the animals with amniotic egg appeared. The amniotic egg is the type of egg produced by birds, reptiles, and egg-laying mammals. In this egg the embryo develops inside a membrane that is either calcium based or leathery.
Feathers – used for flight; have variety of shapes and forms depending on their purpose
Endotherm (warm-bloodness) and four chambered heart – helps for a prolonged flight (Mammals also have these, but they developed individually in the two clades
Large brains and expanded skulls – help sensory perception; birds have especially sharp vision; they can sense ultra violet lights; they also have good hearing abilities and atmospheric pressure detection
Furcula (wishbone)- bone by the fusion of the two clavicles; strengthens the skeleton; helps flight
Pneumatic skeleton – air sacs in bones
Bill- The horny part of the jaws of a bird; a beak
Most male birds do not have external sex organs, but they do have testes, where sperm is produced.
Female birds have two ovaries, although only the left one functions
During copulation, the female moves its tail to the side. The male moves the opening of his cloaca to the female’s cloaca. This process is called cloacal kiss. It happens very fast sometimes in less than one second.
The sperm is stored in the female’s cloaca from a week to a year depending on the species. Then eggs produced by the female become fertilized by the male’s sperm.
Basically two types of flight – gliding flight and flapping flight
Gliding – used by larger birds; flapping – used by smaller birds
Many derived characteristics helping the bird to be lighter (already mentioned- furcula, pneumatic skeleton)
Wings – the most important characteristic; wings shaped like an aerofoil
Because of its shape when air passes over the wing the pressure there becomes smaller (because the same amount of air exerts pressure over bigger area), the opposite effect is experienced below the wing.
The shape and size of the wings changes depending on the habitat of the bird, and the flights that they make.
'aspect ratio' - the ratio of wing area divided by wing breadth
What type of nervous system is present in birds? 8
Central nervous system – brain, spinal chord and nerves
Nerves consist of neurons – cells that transmit micro-electrical pulse
There are two types of neurons-sensory – triggered by sense organs and motor-transmit messages from brain to muscles
Autonomic nervous system – control essential action – heartbeat, breathing, and digestion.
Very well developed areas for hearing and sight, but not so developed olfactory lobes
Distribution: coastal areas of the Caribbean incl . the Bahamas, Cuba, and the Yucatan peninsula ; also southern United States, the Middle East, Africa, and northern South America
Habitat: Saline lakes, coastal lagoons and other shallow salt water territories
Food: Crustaceans, mollusks, insects, algae and diatoms with carotenoid pigments
Live in large flocks and take part in a ritualized group displays that synchronize breeding within the flock
Nest in colonies; group “nurseries” take care of the young ones
Group migration to breeding cites
Filter feeding: while they walk in the water, their long neck allows them to put their bill into the water and collect both water and food; then their tongue pushes out the water and only the food is left in the bill