Form

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Form FuncTioN
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What is a skeleton?
A skeleton consists of the bones that make up
the framework of a body.
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Exercise directions
In this exercise, we will be looking at the form
and function of different skeletons and how they
suit the lifestyle of those animals. Lets try a
few examples.
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observations
Making Observations
Take a few minutes to make some observations
about the form of this animal.
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example
For example, you might say.
Short arms with finger-like appendages
Long, thick-boned tail that reaches to the ground
Elongated rear limbs with shorter bones
connecting them to the pelvis.
Large feet
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inferences
Making Inferences
To make an inference means to draw conclusions
from your observations. What are some functions
of these structures??
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Some questions you might start with are
What are the arms used for?
Why is the tail so long and sturdy?
How might long, skinny legs help it move?
Why are the feet so large?
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Can you guess the animal?
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Kangaroo!
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How does form relate to function?
Click on a part of the animal to find out
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Adaptations
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• An adaptation is a characteristic that helps an
  organism survive and reproduce in its
  environment.
• Can you identify a structure that serves as an
  adaptation for a kangaroo?

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• Lets try another example

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Make some observations about this skeleton
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• Observations
• Hoofed feet
• Thing, long legs
• Long neck
• Short, skinny tail

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Make some observations about this skeleton
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• Observations
• -Thick beak
• Elongated, skinny legs
• Three skinny toes
• Long, tapered neck

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Make some inferences about the functions of these
skeletal structures
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Can you guess the animals?
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Flamingo
Giraffe
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Click on parts of each animal to learn about
their adaptations.
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How do the similar structures of these two
animals serve as different adaptations to their
environments?
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Think about some adaptations in the next
example..
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Observations?
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• Observations
• Long tail
• Small skull
• Short limbs
• Five toes per foot
• Body set low to the ground

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Observations?
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• Observations
• Elongated torso
• Short limbs
• Small skull
• Body set low to the ground
• Front feet larger than back feet
• Five toes

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Can you make some inferences about the structures
of these two animals?
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Can you guess the animals?
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Gila Monster
Iguana
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Click on a part of the animal to learn about
these adaptations..
Gila Monster
Iguana
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How do these structures have similar and
different adaptations?
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Homologous Structures
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• A homologous structure is a characteristic shared
  by related species that has been inherited from a
  common ancestor.
• See example

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In this next example, take note of any homologous
structures that could support an ancestral link
between these two animals.
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Observations?
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• Observations
• Small skull with sharp teeth.
• Forelimbs proportional to rear limbs.
• - Long tail
• - Four paws with claws.

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Observations?
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Observations - Large skull with protruding
fangs. - Prominent front and rear claws. - Broad
shoulder blades - Dense forelimbs - Long tail
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Make some inferences about the structures of
these two animals.
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Can you guess the animals?
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Cat
Lion
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Cats and Lions are closely related species,
therefore, they exhibit structures called
homologous structures
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Can you identify some homologous structures
between cats and lions?
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• Analogous Structures

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Analogous structures are two structures with the
same function but no evolutionary link. See
example
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Observations?
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• Observations
• Hard, outer shell
• Small skull
• No visible teeth
• Four toes
• Thin forelimbs and back limbs

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Observations?
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• Observations
• hard, outer covering
• Long, bony tail,
• Elongated snout
• Three sharp toes

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Make some inferences about the structures of
these two animals.
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Can you guess the animals?
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Armadillo
Box Turtle
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Turtles and armadillos are unrelated species that
share similar characteristics. Can you identify a
few analogous structures between these two
animals?
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Identifying Related Species
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What characteristics do these three animals have
in common?
Do they appear to be related or unrelated?
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• Lets take a closer look at their skeletons

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Armadillo Skeleton
Armadillo
Hard, outer covering
Elongated snout
Long, bony tail
Sharp front claws
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Anteater
Long tail that drags behind the animal
Long, tapered snout
Short, forelimbs with claws
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Sloth
Sharp claws
Long forelimbs and hind legs, relatively similar
in length and size.
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Based on your observations, are these animals
related or unrelated? Or in other words, do they
have homologous or analogous structures?
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Order Xenarthra
All three animals are classified in the order
Xenarthra because they all lack incisors or
canines and have 2-3 predominate claws. These
common structures are known as homologous
structures.
Anteater
Sloth
Armadillo
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Identifying Related Species

• Make observations about the forms of different
  organisms.
• Draw inferences about the functions of those
  forms.
• Consider how those forms may serve as
  adaptations.
• Compare those adaptations to other organisms.
• Do the forms and adaptations represent homologous
  or analogous structures?

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• What else might you need to know in order to
  identify related species?

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Conclusions

1. By making careful observations and inferences, we
   are able to formulate hypotheses on the
   relationships between form and function.
2. Certain structures have specific functions
   according to the organism and the environment.
   These are called adaptations.
3. Structures of related species are known as
   homologous structures.
4. Similar structures of unrelated species are known
   as analogous structures.
5. By analyzing the structures of these organisms,
   we can begin to draw conclusions about their
   origins and relations.

• 1.

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The End
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The Kangaroo Tail

• A Kangaroos Tail is long and muscular, extending
  all the way down to the ground. It serves as a
  sturdy prop while the kangaroo sits or stands.
  When the kangaroo fights, sometimes the only limb
  touching the ground is the tail!
• ??Can you think of any human inventions that may
  resemble a kangaroo tail in both form and
  function?

BACK
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Forelimbs

• A Kangaroos Forelimbs are thin and short and
  help the animal hop forward.
• Compare the kangaroos forelimbs to the arms of a
  runner. How are they similar and how are they
  different in both form and function?

BACK
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Kangaroo Hind legs

• The Kangaroos hind legs have tendons that act
  like rubber bands, propelling the animal forward
  in quick, strong leaps.
• Its large feet help the animal sit and balance,
  and are also a very powerful defense mechanism.
  No one wants to experience the kick of a
  kangaroo!T

BACK
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Giraffes Legs
Because its legs are so long, a walking giraffe
moves both legs on a side at almost the same
time. It can gallop at up to 56 km/h
BACK
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Giraffe Tail
Like many animals, a giraffes tails function as
fly swatters. The zebra to the right demonstrates
with his tail, which has a similar structure to
the giraffes tail.
BACK
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Giraffe Mouth
Their mouths are designed to pick leaves from
trees and have flat teeth to crush the
vegetation. Therefore, their feeding structures
are adapted to their feeding habits.
BACK
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Giraffe Neck
Giraffes tend to feed on the leaves from tall
trees where they experience less competition from
other herbivores. To reach those leaves, they
need long necks.
BACK
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Flamingo Neck
A flamingos long neck helps it extend down into
the water to feed. It is also used to stabilize
the bird during flight.
BACK
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Flamingo Wings
Flamingos are capable of flying distances up to
300 miles in one night. They typically extend
their necks forward and their legs behind them
during flight and reach speeds of up to 30mph.
BACK
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Flamingo Legs
Flamingos have long legs that allow them to wade
into deeper waters than their competitors. Their
webbed feet help them to stabilize themselves in
the mud.
BACK
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Flamingo Beak and Feeding
Flamingos have a unique feeding mechanism whereby
they hold their heads upside down and filter
algae, seeds, and marine invertebrates such as
shrimp and mollusks from the water through their
beaks.
BACK
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Human arm, bat wing, and whale flipper.
Bat wing
Whale Flipper
BACK
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Analogous Structures
Butterfly wings and bat wings resemble each other
in form and function, but there is no ancestral
link between the two.
BACK
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Iguana Claws
An iguana has four feet with five digits on each.
These claws are used mainly for climbing seeing
as the iguanas main habitat is in trees.
BACK
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Iguana Tail
The iguanas tail has two functions. First, as a
means of balance during climbing. Second, as a
means of defense against predators. It can whip
and distract predators and sometimes, may
disconnect from the iguana, but dont worry its
grows back!
BACK
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Iguana Head and Mouth
Iguanas have spines starting at the back of
their head and continuing down their back which
make it more difficult for predators to swallow
them. Their flat mouths crush vegetation and
fruit which are the main sources of nutrition for
these reptiles.
BACK
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Gila Monster Tail
A Gila monsters short, fat tail serves as a
storage place for fat. When the animal is low on
food sources, it uses the fat from its tail as a
source of energy.
BACK
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Gila Monster Head
The Gila monster has a large head with a strong
lower jaw, which is where the animal stores its
venom. One reason why the head sits low is so the
animal may lick the ground which is how it picks
up the scents of its prey.
BACK
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Gila Monster Claws
The Gila monsters short legs and short claws are
ideal for digging burrows, digging for eggs and
food, and climbing.
BACK