One example of an homologous trait, is the forearm. Not only do humans posses this trait, but cats, whales, horses, birds, bats, and all other vertebrate do as well. Although the trait contains the same type of structure, the forearm itself serves a different purpose for each animal which posses this trait. The purpose of the forearm results in the different needs of survival of each animal and their habitat. For whales the forearm is used for swimming, for bats and birds it is used for flying, for horses and cats it is used for running, and for humans it is mostly used as a way to bend the arm itself.
Analogous TraitsAn example of an analogous trait in two different species is the claw of both the scorpion and the crab. The crab can live on both land and in the ocean or other water source, while the scorpion usually resides in a desert terrain. Both use these claws for the same purpose, such as eating and defending themselves from predators. Not only do these two species use their claws for the same purpose, the shape and proportion of the claws are almost identical to one another. However, these two animals are considered two different species, the scorpion being an insect and the crab being a crustacean. They both come from the ancestor, Anthropoda, as shown in this courses text Introduction to Anthropology.
Melissa,
ReplyDeleteI really like the examples you gave for the assignment. I especially like the species you chose for the analogous traits. It is interesting the things these species have in common while still being totally different from one another. I like the way you pointed out how they are similarly shaped and how they use their claws for the same things. Good job!
Melissa,
ReplyDeleteI would've never thought if the scorpion and the crab, you did a good job explaining their analogous traits. While they are obviously two different creatures they do share some similarities in their traits.
Okay, good bunch of homologous traits. It might have benefited you to stick to just two organisms so you could spend more time exploring and describing the pressures that resulted in these traits. What can you tell be about the ancestry of these traits? Did the common ancestor of all of these limbs also possess this similar structure?
ReplyDeleteDid you mean ARthropods for your analogous traits? Arthropods are a general classification term for segmented organisms with an exoskeleton. It is likely true that the common ancestor was an arthropod, the question is whether they had claws. I tend to think you are correct that the claws arose independently, but I'm not sure. Interesting comparison and good images.
Professor Rodriguez,
ReplyDeleteI apologize for the late response, I had replied earlier in the week and I now see it had not actually posted.
I did have trouble dating back the ancestor of the homologous traits. My assumption would be that the trait, in a very similar form, was indeed possessed by the ancestors, but has developed over time due to need and survival. The limb is a very important trait, in which as shown, can be used for tools, eating, and means of travel.
Yes, I did mean anthroprods, however, I too do not believe the ancestor has possessed these traits. My conclusion is the two creatures in question, the crab and the scorpion, have independently developed these traits as a need of survival in their habitats.