Homologous Structures: Cat & Whale
Homologous structures can be found in the forelimbs of multiple
differing mammals such as that of cats and whales. When two or more structures
are essentially similar to each other in how they’re constructed but are
modified through evolution to perform different functions, they are homologous.
When studying the homologous structures in both cats and whales, you will find
that the specific form, construction and the number of bones in their forelimbs
are very similar. The cat’s forelimb (pictured below) is used for walking and
climbing while the whale’s forelimb (also pictured below) is used for swimming.
In addition, although both a cat and whale both have similar
vertebrae construction such as the Cervical, Thoracic, Lumbar and Caudal areas,
both have unique physical functions. The function of the whales vertebrae is to
assist with swimming whereas for the cat, it is used to help walk, run, jump
and contort in various positions.
**Whale Image
**Cat Image
Common Ancestor
It would seem that the common ancestor that cats and whales
share with with other mammals may possibly be a rat-size animal that more than
likely weighed no more than about a half a pound that possessed a long furry
tail and lived on insects. Recently scientists have discovered after conducting
a comprehensive six-year study of the mammalian family tree, they have been able
to identify and reconstruct what could be the most likely common ancestor of
most mammals. It was found that the animal had numerous anatomical
characteristics for live births that were similar to those of all placental
mammals and led to over 5000 living species ranging from humans, elephants,
bats, whales, cats and dogs. This discovery has been very insightful in
shedding new light on the evolution of all mammal life.
**Possible Ancestor
** Cat and Whale
Analogous Structures: Platypus and Duck
When studying both the Platypus and duck species, both bird
types look very similar with features consisting of both featherless necks and
heads, and feed on carrion. However, with the exception of these similarities, both
of these species belong to different families. Although the duck-billed platypus
is an egg-laying mammal which is a behavioral trait that evolved dominantly in
birds, it is not related to the avian family by any other characteristic. A
duck can lay eggs, fly, swim and although has the same bill as the Platypus, however
the duck is from reptile origin.
The duck-billed platypus is a subfamily of mammals. Although
they feed their young with milk, they do so by having their milk ooze from
glands under the skin, and their young lap it up from a patch of fur. They
don’t fly and walk awkwardly on their knuckles to protect their webbing while
on land. They also carry venom in their hind legs and they retract their
webbing on land to reveal their claws. Ducks however, waddle because of their
webbed feet and they can fly. Also their feet have no nerves of blood vessels
which make them unable to feel the cold.
Analogous Ancestor
The Platypus seems like a hybrid of part bird part mammal
and part reptile. We also know that ducks are birds and also have reptile
origins as well.
I really liked the two animals you chose to compare for your analogous portion of the blog! You had really great information about the platypus that I never knew! I enjoyed reading your blog, good job!
ReplyDeleteVery good opening explanation of homologous traits. Just to be clear, were you comparing limb structure or vertebral structure of the cat and whale as your homologous traits? The limb structure of these two species is a clear pair of homologs, but the vertebral column doesn't differ in function significantly. Both serve as protection of the spinal cord and as the central connecting column of the body structure. Both are only indirectly related with locomotion,as a means of connecting the limbs to the rest of the body. I would need more explanation to justify considering the vertebral column as homologous. Interesting idea but need more information on the functional differences. Okay on limbs, however.
ReplyDeleteGood explanation of the ancestral information supporting these homologous pairings.
On the right track with your analogous pairings but you needed to focus on one trait and explore how the environmental/functional aspects have resulted in their analogous status. Why do both of these species have duck bills? Also confused as to why you refer to both of them as "bird types"? The duck has feathers on it's neck (so not "featherless) and the platypus has hair, like all mammals.
I know that the issue of ancestry can be confusing but what we are looking for is evidence that the common ancestor did NOT possess this trait or that at least one of these organisms evolved the trait independently from that common ancestor. So let's take the bill structure for example. We know that with the platypus being a mammal and the duck being a bird, the common ancestor of the two was reptilian, as reptiles served as ancestors to both groups. Bills are not reptilian structures. We also know that duck bills are derived traits of ducks themselves and and are also uniquely derived traits of the platypus, since it is the only mammal that has one. This is sufficient to confirm that these are analogous traits, but we needed to focus on one trait to work through this.
Great blog. Lots of detailed information. Enjoyed learning about the comparisons and similarities of the platypus and the duck. I was surprised to learn about the similarities of a whale and a cat though. Would have not guessed that these two belonged under the same Homologous category. Good job.
ReplyDeleteThis comment has been removed by the author.
ReplyDeleteI liked your blog post; your illustrations and explanation on cats and whales are well supported, it gives the reader (in my case) an easier method to absorb the information. From my researched I concur that vertebrate species share a common evolutionary ancestor and thus have homologous traits. Another example would be the whale's flipper is homologous to the human hand, although they serve different functions they have evolved from a common ancestral structure.
ReplyDelete