A.
Homologous trait: The flipper of Whale and
Alligator forelimb
1.
Alligators, like other
crocodilians, are large animals with powerful tails that are used both in
defense and in swimming. Their eyes, ears, and nostrils are placed on top of
their long head and project slightly above the water when the reptiles float at
the surface, as they often do. Alligators can be differentiated from crocodiles by the form of their jaw and
teeth. Alligators possess a broad, U-shaped snout and have an “overbite”—that
is, all the teeth of the lower jaw fit within (lingual to) the teeth of the
upper jaw. The large fourth tooth on each side of the alligator’s lower jaw
fits into a socket in the upper jaw.
Whales’ larger species of
aquatic mammals belonging to the order Cetacean. The term whale
can be used in reference to any cetacean, including porpoises and dolphins, but in general it is applied to
those more than 3 meters (10 feet) long. An exception is the 2.7-metre dwarf sperm whale (Kogia simus),
so called for its otherwise striking resemblance to its larger namesake. Whales
are the heaviest known animals, living or fossil, reaching a maximum size in
the blue whale (Balaenoptera musculus)
of perhaps more than 30 meters and 200 metric tons (220 short [U.S.] tons).
Whales flipper (bone structure)
Alligator forelimb (bone structure)
2.
The bones in the forelimbs of alligator and
whales are the same so as the structure of bones attached to each other are
similar. Both are similar in radius bones, ulna, carpals, metacarpals,
phalanges. Tetrapod
is a group of vertebrate animals with four limbs with five digits on each limb.
However, the size and shape of the limb bones may also be different from one
animal to another.
3.
Since both species are vertebrates I would say
that the common ancestors of the two species are the tetrapods. It is said to
be that in evolution the tetrapods, fishes and vertebrates animals diverged
into one. Thus during the Devonian Age or age of fishes marked the numerous
species of fish. Since then evolution of fishes started. Bony fishes started to
resemble cartilaginous fins. Biologists believe that over million years the
only vertebrate exist are the water creatures. As it time evolve so as the
water dwelling creatures and started to developed legs and hips which eventually develop lungs
and would able to survive the land surface and the reason to believe how
alligators shares same bone structure of the forelimb as to the whales.
4.
Photos:
Alligator
Whale
B. Analogous trait: Tasmanian Devils
and Hyenas
1.
Tasmanian devils are related to quolls; both
are classified in the family Dasyuridae. The teeth and jaws of Tasmanian
devils are in many respects developed like those of a hyena. The pouch, when relaxed, opens
backward, but, when the muscles are contracted to close it, the opening is
central. During the breeding season, 20 or more eggs may be released, but most
of these fail to develop. In most cases just four young are produced after a gestation period of about three weeks;
these remain in the pouch for about five months. Overall, female offspring
outnumber males about two to one. is a carnivorous marsupial of the family Dasyuridae. The size of a small dog,
it became the largest carnivorous
marsupial. Hyena (family
Hyaenidae), also spelled hyaena , any of three
species of coarse-furred, doglike carnivores found in Asia and Africa and
noted for their scavenging habits. Hyenas have long
forelegs and a powerful neck and shoulders for dismembering and carrying prey.
Hyenas are tireless trotters with excellent sight, hearing, and smell for
locating carrion, and they are proficient hunters as well. All hyenas are more
or less nocturnal.
2. Tasmanian Devil and Hyena shares common resemblances. Both
are mammals, carnivores and dog-like resemblance. Both came from different
ancestors and environment however not homologous but they share a lot of
analogous traits.
Tasmanian Devils are stocky carnivorous marsupial with heavy
forequarters, weak hindquarters, and a large squarish head. Hyena skulls superficially
resemble those canids however it is heavier and larger than ordinary canids
with shorter facial portions. Both have similarity of skull structure.
The Tasmanian devil is named for the Australian
island-state of Tasmania, its only native habitat. Vaguely bearlike in
appearance and weighing up to 12 kg (26 pounds), it is 50 to 80 cm (20 to 31
inches) long and has a bushy tail about half that length. The smaller brown
hyena weighs about 40 kg; the coat is shaggy and dark with an erectile white
mane over the neck and shoulders and horizontal white bands on the legs. Hyenas
usually found in East and Southern Africa. Hyenas have relatively short torsos,
and are fairly massive and wolf-like in build, but have lower hind quarters,
high withers and their backs slope noticeably downward toward their croups. The
forelegs are high, while the hind legs are very short and their necks are thick
and short. They
are dog-like animals with a sloping body, as their front legs are longer than
their hind legs. They have a short, sandy coat, covered with dark brown spots
or stripes on the body and legs
Tasmanian Devils coat is mainly black, and there is a
whitish breast mark; sometimes the rump and sides are white-marked as well. Hyenas
color is pale gray with black throat fur and stripes on the body and legs. The
hair is long, with a crest running from behind the ears to the tail; the crest
is erected to make the animal look larger.
Tasmanian Devils Gaping jaws and strong teeth, along with
its husky snarl and often bad temper, result in its devilish expression. It is
mainly a scavenger, feeding on
carrion such as road kill and dead sheep. The larvae of certain beetles are its
major source of live food, but it has been known to attack poultry. While
Hyenas are known for being a talented scavengers. Their jaws have bone-crunching strength and their
digestive systems are adapted to digest bone and skin, animal parts that other
predators cannot handle. Both are scavengers, bad tempered and have strong jaws
and teeth.Though Tasmanian
devils are known to be nocturnal however Hyenas tend to be nocturnal.
3. As hyenas shares a lot of common
resemblances in many aspects to canines but it was believed that it originated
in Miocene period which is also believed from viverrid-like
ancestors that evolve to a dog-like structure. While Tasmanian Devils are from Dasyuridae
family. Biologists speculate that their extinction on
the mainland is attributable to the introduction of Asian dogs, or dingoes.
4. Photos:
Hyena (family: Hyaenidae)
Tasmanian Devil (Family: Dasyuridae)
Great job comparing a reptile and a mammal for limb structure. That was a great comparison and yes, their common ancestor would be an early tetrapod, most likely an early reptile. Excellent discussion throughout on the homologous trait.
ReplyDeleteI was a little concerned with your analogous trait comparison as I was having some difficulty figuring out the similar trait that was the focus of your decision. But your description of the powerful jaws and the scavenging was very good and both of these organisms have very different evolutionary histories. Well done.
Thank you Dr. Rodriguez for the inspiring thoughts!
DeleteHi Sally,
ReplyDeleteWhat a great post.
I learned that The flipper of Whale and Alligator forelimb are homologous traits.
From the diagrams you provided it makes it clear how traits exhibit differences between the two
species even though their functionality is the same. (Ability to move)
As for your analogou Tasmanian Devil and Hyena, it hard to believe they come from different ancestors. The pictures look so similar!
Great post!
analogous traits*
Delete