Homologous Traits
The beaver is a semi-aquatic,
broad-tailed mammal native to North America and Eurasia that builds
dams for protection from predators and for easier access and storage
of food. The elephant is the largest land mammal that is native to
Africa and Asia; elephants are highly intelligent and live in matriarchs
in which every year the oldest female leads the herd across many
miles to the water sources that she remembers.
The teeth of a beaver and the tusks of
an elephant are homologous traits because they are related features
that have evolved from a common ancestor. Although they appear to be
different structures they are both evolved from the incisor teeth
that they shared in their common ancestor. Beaver teeth and elephant
tusks have changed over time to perform different functions but they are
both considered to be the incisor teeth in either animal.
Beaver teeth never stop growing and get continuously filed down as they get used throughout their lifespan. They mainly function to chew down trees for building dams and lodges. Elephant tusks also grow continuously and are used for digging, fighting, and carving tree bark for food.
Beaver teeth never stop growing and get continuously filed down as they get used throughout their lifespan. They mainly function to chew down trees for building dams and lodges. Elephant tusks also grow continuously and are used for digging, fighting, and carving tree bark for food.
The common ancestor between the beaver
and the elephant is believed to be Juramaia, a small, furry rodent
that survived the apocalypse that killed the dinosaurs. This rodent
has also been hypothesized to be the common ancestor to all mammals.
Analogous Traits
The octopus is
a squishy invertebrate creature that has two eyes, three hearts and
eight limbs, and lives deep in the ocean. The human is a vertebrate
that lives completely on land and has two eyes, one heart, two arms
and walks upright on two legs.
The eyes of the
octopus and the eyes of a human are an analogous trait that is shared
by both species but they evolved independently from each other out of
the necessity for vision.
The anatomy of the human and octopus eyes may appear similar but function very differently. The human eye focuses on an object by changing the shape of the lens with the eye muscles, while the octopus protracts and retracts the lens to and from the retina, like a camera-lens. The nervous and cellular functions are also completely backwards and opposite between humans and the octopus, but it has to do with the fact that we evolved to see through air, and octopuses evolved to see through water, resulting in completely different types of eyes.
The anatomy of the human and octopus eyes may appear similar but function very differently. The human eye focuses on an object by changing the shape of the lens with the eye muscles, while the octopus protracts and retracts the lens to and from the retina, like a camera-lens. The nervous and cellular functions are also completely backwards and opposite between humans and the octopus, but it has to do with the fact that we evolved to see through air, and octopuses evolved to see through water, resulting in completely different types of eyes.
Our species is
so different from the octopus that we may not appear related at all
but somewhere in the timeline of evolution, we all still had to have
shared the same common ancestor. The reason that the trait for eyes
between humans and octopuses is analogous is because our common
ancestor had not yet evolved eyes until after the evolutionary split
occurred in the family tree. One branch that led to humans and the
other that led to octopuses and somewhere in between the eyes evolved
independently as a means of the necessity to survive, or in other
words, from natural selection.
I enjoyed reading your post, very detailed and interesting. I would have never thought to put an elephant and a beaver in the same catergory, but once explained it makes complete sense.
ReplyDeleteYou did a great job explaining the features of the beaver's teeth and the elephant's tusks. It was interesting to learn that their common ancestor could have been a small furry rodent. Also, good information on explaining the functions of both their eyes. You described it well and I enjoyed learning about it.
ReplyDeleteGreat example of analogous traits of environmental adaptation as octopi evolved to see through water and the human eye through air. Your post was educating.
ReplyDeleteGreat choice of homologous traits and very good description. Thorough.
ReplyDeleteJust for clarification, the rodent common ancestor possessed the incisor teeth, passed them down to its descendents, and in the elephant and beaver, they became these unique structures? That needed to be clarified to confirm homologous status.
The eye is an excellent example of analogous traits, having arisen several times independently throughout natural history. Good description on the similarities and key differences in these structures.
"The reason that the trait for eyes between humans and octopuses is analogous is because our common ancestor had not yet evolved eyes until after the evolutionary split occurred in the family tree."
Beautifully explained. Well done. Great images as well.