vs 
Human Vs. Cats
The two different species I have selected in the Homologous
trait category is Humans and cats. Humans are homo sapiens while cats are
felius catus. Humans are bipeds while cats are quadrupeds. One thing that is a homologous
trait is that the bone structure of the Human and cat are very much similar. The human’s forelimbs have a Humerus, Radius, Ulna, Carpals, Metacarpals,
and Phalanges, The cats forelimbs have the same identical bones even though at
first glance they appear to be different to the naked eye. Even though the
structures are comprised of the same bones, they are very much different in the
way they function. Humans have elongated fingers and hands that are used to grasp things. Humans
are able to grasp things because of the opposable thumbs. The hands and fingers are used to hold tools
and throw objects. Humans also have forelimbs that bend at the elbow which is
helpful when consuming nutrition and food. Cats on the other hand are Quadra
pedal meaning they walk on all four limbs and they do not have opposable
thumbs. The cats forelimbs cats are
digitigrades meaning they walk directly on their toes. When cats walk their
back legs step directly behind their
front paws which results in
minimal noise helping them to sneak up on their prey. It also increases their
speed when running after their pray and when jumping and pouncing.
After doing a lot of research it is said that the common ancestor
of the human and the cat would have been a placental mammal over 70 million years ago. In 1997 the
fossils of this so called ancestral mammal’s fossils were discovered in the
Gobi Desert and they called it Maelestes gobiensis. The mammal has the same
bone structure so we know it had the same homologous trait, but the function of
how this trait was used is still a mystery.
vs 
Dolphins Vs. Sharks
For the analogous trait the two species I chose were
Dolphins and Sharks. A dolphin is a
mammal that lives in the ocean. They can be from four feet all the way up to 30
feet. The dolphin’s body is adapted for fast swimming. They also communicate
and navigate using sonar. Dolphins have very good eye sight in and out of the
water. The dolphins body is comprised of a beak which it the mouth, a melon
which is their head. A blowhole they use for getting air, a dorsal fin which is
on the topside of their body, a tail fin which is called fluke used for
swimming and flippers that they use for maneuvering through the water. Dolphins
are carnivores.
Sharks are fish with approx. five to seven gill slits that
they use to breathe underwater. They have
two pectoral fins that are fused to the head that they use to maneuver through
the water. Sharks also have two sets of dorsal fins used for steering in the
ocean. The shark has a tail fin as well but it is called a caudal fin. The last
two fins a shark have an anal fin and a pelvic fin. Sharks eye sight is not a
good as dolphins, and they lay eggs where the dolphin does not. Sharks are also
carnivorous.
The analogous traits
these two have in common is they both have the same body shape for example the
tail fin, the dorsal fin, and the flippers/pectoral fin which they use to swim
through the water as they prey on fish. They are both fast swimmers.
If you go way back they common ancestor could have possessed
these common traits. We know that these traits are analogous because Dolphins
are Mammals and Sharks are fish. Even though sharks and dolphin have similar
body shapes and possess similar traits they are not genetically related from
common decent.
I think your section on the homologous trait was very good. I also wrote my blog about forelimbs though I chose two different species than you. It's interesting to see how many species share the homologous trait of the forelimb. Each species look entirely different, lives in completely different environments and uses their forelimbs in many different ways yet they possess the same types of bones. So interesting! Good post
ReplyDeleteGreat and thorough description of your homologous pairing. Well done.
ReplyDeleteGood research on a possible ancestor, but we don't even need to get that specific. Since both of these organisms are mammals, we know that their common ancestor was an archaic mammalian ancestor who possessed the generalized forelimb structure, passed on to these two descendents.
Good description on your analogous pairings.
You are just on the edge of fully explaining the issue of ancestry, but just because organisms are distantly related doesn't automatically mean treats are analogous. The tiny ear bones in our middle ear and the branchial (gill) arches of fish are genetically related. They are homologs. No kidding. And the common ancestor of these two organisms would have been a very early archaic fish that likely possessed this body shape and likely passed that shape onto early sharks. So how do we know the body shape of these two organisms is analogous? Well, as you say, we know that dolphins are mammals and arose from land mammals who did NOT possess that body shape. That means this trait is a derived trait for dolphins, arising independently from that common ancestor. That is what confirms that these are analogous traits.
Good images.
thank you
ReplyDelete