Homologous Traits
Porcupine
Porcupines are covered with a coat of sharp spines,
or quills, that defend and camouflage them from predators. They are original to
the Americas, southern Asia, and Africa. Porcupines are the third largest of
the rodents, behind the capybara and the beaver. Most porcupines are about
25–36 in (63–91 cm) long, with an 8–10 in (20–25 cm) long tail. Weighing
between 12–35 lb (5.4–16 kg), they are round, large and slow. Porcupines come
in different shades of brown, grey, and the unusual white.
Harbor Seals
The harbor seal, also known as the common seal, is a
true seal found along temperate and Arctic marine coastlines of the Northern
Hemisphere. They are found in coastal waters of the northern Atlantic and
Pacific Oceans.Common seals are brown, tan, or gray, with distinctive V-shaped
nostrils their fur serves them as insulation. An adult can attain a length of
1.85 meters (6.1 ft) and a mass of 132 kilograms (290 lb). Females outlive
males (30–35 years versus 20–25 years). Common seals stick to familiar resting
spots, generally rocky are where they are protected from adverse weather conditions
and predators.
Homologous Trait
The homologous trait shared by a harbor seal and a
porcupine is their hair. Both have hair all over their body; however, they do
not have the same function. A porcupine quills
or hair serve as a defensive mechanism. These quills typically lie flat until a
porcupine is threatened, then leap to attention as a persuasive deterrent.
Porcupines cannot shoot them at predators, but the quills do detach easily when
touched. Many animals come away from a porcupine encounter with quills bulging
from their own bodies. On the other hand Harbor seals use their hair as
insulation. Since Seals mainly live in cold environments their fur helps them
stay warm.
Common Ancestor
Their common ancestor is a mammal because all mammals
have hair.
Analogous Traits
Shark
Sharks are a group of fish characterized by a
cartilaginous skeleton, five to seven gill slits on the sides of the head, and
pectoral fins that are not fused to the head. Shark skeletons
are very different from those of bony fish and terrestrial vertebrates. Sharks
and other cartilaginous fish have skeletons made of cartilage and connective
tissue. Cartilage is flexible and durable, yet is about half the normal density
of bone. Because sharks do not have rib cages, they can easily be crushed under
their own weight on land.
Dolphins
Dolphins are marine mammals closely related to
whales. They vary in size from 1.2 m (4 ft) and 40 kg (90 lb) (Maui's dolphin),
up to 9.5 m (30 ft) and 10 tonnes. Dolphins have a dorsal fin, but have no
internal support. They are found worldwide, mostly in the shallower seas of the
continental shelves, and eating mostly fish and squid. Dolphins are among the
most intelligent animals, and their often friendly appearance and their playful
attitude have made them very popular in human culture. Dolphins
have a streamlined fusi form body, adapted for fast swimming.
Analogous
Trait
Despite the fact that sharks are cold-blooded
relatives of fish and dolphins are warm-blooded mammals, the two animals share
a number of characteristics. They have sleek bodies, are a similar color, and
have prominent triangular dorsal fins. A dolphin's fin has a
curved silhouette, while most shark fins have a straight forward edge. In some
shark species, the rear edge of the dorsal fin may be curved. Some types of
shark can also change the attitude of their dorsal fin, so that it droops
slightly. Although different, both the dolphin and shark use their pectoral fin
to stop, steer and coordinate different movements.
Common
Ancestors
No, in my opinion the dolphin’s ancestor did not
posses this analogous trait; however, the shark’s ancestors did. I believe that
dolphin’s developed this trait over time to survive in their environment and be
able to maneuver their bodies easier.
