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.
