a. A whale has blubber and flippers to swim and survive in the ocean while humans live on land with limbs to walk and move around.
b. The bone structures are very similar, they are very different. A whale flipper is used to swim while the human arm does many different things. Both species each have a large upper arm bone and the lower part of the limb is made up of two bones - a larger bone on one side and a smaller one on the other.
c. The common ancestor between whales, humans, and other mammals is a rat-like organism called a Dormaalocyon Latouri. They share a similar nervous system and organ system, as well as all being mammals.
d.
2. Analogous traits
a. An octopus is a cephalopod that lives in the ocean while a human is a mammal that lives on land.
b. The eye of an octopus and a human is an analogous trait. Similarly, they both have lenses to react to light, a pupil that is able to restrict incoming light, a retinal surface, and an optic nerve.The eyes also differ in a few ways. The eyes focus light on the retina in different ways. Humans focus their eyes by changing the shape of the lenses using the ciliary muscle while an octopus focuses by moving the lens closer or further away from the retina, as a camera would do. The cellular organization is also very different.
c. The common ancestor is known to be bilateria. The common genes and the larger number of conserved genes show that this could have led to the evolution of the camera eye.
d.
I think it is cool to see the bone structure side by side. It looks as though both started the same and were just stretched differently in different places. It is way way back but it is crazy to think that humans and whales came from the same place. The eye is a remarkable thing. It is also remarkable that our eye is so similar to that of an octopus. Great work! This is a really interesting read.
ReplyDeleteIn general, good description of your homologous pairings. You explain the different function but how does their structure differ? Can you use the different functions to explain the different structures?
ReplyDeleteIt is possible that you are correct on the common ancestor but we don't even need to get that specific. We just need to understand that the common ancestor was an archaic mammal, but did that mammalian ancestor possess the archaic limb structure shared by these two organisms? And why is that important in order to confirm that these two traits are indeed homologous?
Good description of your analogous pairings. but what do we know about their ancestry that helps confirm that they are indeed analogous and not homologous traits? Did that early common ancestor possess an eye structure? If these were analogous traits, would we expect the human eye and the octopus eye to share common genes?
Remember that analogous traits arise independently from each other. That means the genes controlling the production and action of these traits would be unique in the two species, not shared from common descent. We know from their drastically different structure and specific function (along with information on ancestry) that these two eye structures arose independently from each other. The eye is actually a classic example of analogous traits and it has evolved independently multiple times across the animal world.
Other than this issue of ancestry for your analogous traits, good post.
I like your example of homologous traits, I used the same example as well. You described how the traits differed between humans and whales well. I personally could not find the common ancestor between the two species so it's nice to find out what it is from your post. The example of analogous traits was neat because I would have never compared a trait that us humans share with octopus. You were very detailed with the differences between the eyes and it was even nice how you brought in a comparison with cameras. It made it easier to understand the differences. Overall I thought your post was well done and informative.
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