ShareOffspring Traits - How Can I Survive Without You?
Birds have hollow bones
Over time organisms have developed structures that help them to survive
in their environments. Organisms with traits that help them survive are
the ones that will live long enough to reproduce and pass these favorable
traits to their offspring.
While a trait may allow an organism to survive in one area, it may not survive in a different environment. Traits that are useful are passed from parent organisms to their offspring.
Look
closely at a reason why birds are able to fly. Unlike you and me, bird bones
are hollow. You know that with less material in the same area, there is
a lower density. This lowere density in a bird's bones provide something
which allows them the ability to fly. As you look at the bird bones at the
right, you should notice that you can actually see the holes in each of
the bones. Truly hollow bones would break easily, therefore there is still
some material inside each bird bone. Watch the QuickTime video below to
see an example of a bird flying.
Look closely at the video of the bird flying above. If you need to, press the "Play" arrow and watch it more than once!
Remember that most birds need to fly to survive. Having less dense bones is an advantage as this trait makes the bird much lighter. To understand why being lighter is an advantage, imagine running a race wearing a 50 pound backpack verses running the race without all the extra weight. Flying, for birds, is like running the race, for humans, having less dense bones is like removing the backpack.
Fish have fins
Fish, unlike birds, do not need to be able to fly in the air. They, however
must have fins that allow them to move easily through the water. Fins
are an advantage to fish, because fins help fish move around easily in
their watery homes. It’s kind of like putting on flippers when you
swim. The flippers help you move faster through the water.
To observe the fish fins, you must look closely at the fish in the beaker in the movie above. The fins are moving slowly at the sides of the fish.
Analysis:
- How would the hair on a bear help it to survive?
- What characteristics does a lizard have which help it survive in a
desert?
- What specific traits does a mule deer have which allows it to survive
in Utah?
