Download “Why Do”

“Why Do”
Questions about structural and
behavioral adaptations.
Design Questions
• You will design questions based on research in
the following areas:
Gills on fish
Hollow bones in birds
Xylem in plants
Migration
Hibernation
Storage of food in a bulb
Examples
• “Why do…” for structural adaptations. Ex.—
Why do roses have thorns?
Produce 6 questions and write each
one on an index card.
• “Why do…” for behavioral adaptations. Ex.—
Why do birds sing?
Produce 6 questions and write each
one on an index card.
Gills in Fish (structural)
•
A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from
water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have
adapted to allow respiration on land provided they are kept moist. The microscopic structure of a
gill presents a large surface area to the external environment.
•
Many microscopic aquatic animals, and some that are larger but inactive, can absorb adequate
oxygen through the entire surface of their bodies, and so can respire adequately without a gill.
However, more complex or more active aquatic organisms usually require a gill or gills.
•
Gills usually consist of thin filaments of tissue, branches, or slender tufted processes that have a
highly folded surface to increase surface area. A high surface area is crucial to the gas exchange of
aquatic organisms as water contains only a small fraction of the dissolved oxygen that air does. A
cubic meter of air contains about 250 grams of oxygen at STP. For a typical freshwater oxygen
concentration of 5 parts per million by mass, a cubic meter of water will contain 5 grams of oxygen.
This is about 1/50th of the oxygen of the same volume of air.
•
With the exception of some aquatic insects, the filaments and lamellae (folds) contain blood,
from which gases are exchanged through the thin walls. The blood carries oxygen to other parts
of the body. Carbon dioxide passes from the blood through the thin gill tissue into the water. Gills
or gill-like organs, located in different parts of the body, are found in various groups of aquatic
animals, including mollusks, crustaceans, insects, fish, and amphibians.
Hollow bones in Birds (structural)
•
Birds have a lightweight skeleton made of mostly thin and hollow bones. The keelshaped sternum (breastbone) is where the powerful flight muscles attach to the body.
Birds have a smaller total number of bones than mammals or reptiles. This is because
many of their bones have fused together making the skeleton more rigid. Birds also
have more neck (cervical) vertebrae than many other animals; most have 13 to 25 of
these very flexible neck vertebrae (this helps them groom their feathers). Birds are the
only vertebrate animals to have a fused collarbone called the furcula or wishbone and a
keeled breastbone. Below is a diagram of a typical bird skeleton.
1) Skull
2) Cervical Vertebrae
3) Humerus
4) Second digit
5) Metacarpals
6) Fourth digit
14) Ilium
19) Halux
7) Third Digit
15) Pubis
20) Digits
8) Radius
11) Synsacrum 16) Pelvic girdle 21)Tarsometatarsus
9) Ulna
12) Pygostyle
17) Uncinate process 22) Tibiotarsus
10) Scapula
13) Ischium
18) Femur
23) Keeled sternum
24) Coracoid 25) Furcula (or wishbone)
Xylem in Plants (structural)
• In vascular plants, xylem is the tissue that
carries water up the stem. In trees, it
constitutes wood, hence the word is derived
from the Greek word for "wood". Together
with phloem, xylem is one of the two
transport tissues of plants.
Cross section through
the stem of a magnolia
plant, showing xylem
vascular tissue for
transporting water and
mineral nutrients from
the roots to the main
body of the plant.
Cross section of
vascular bundle in
wood (xylem cells
visible).
Migration
Mexican free-tailed bats migrating
south to Central America and
Mexico during the winter. (picture
on the left)
• Animal migration is the relatively long-distance movement of
individuals, usually on a seasonal basis. It is a phenomenon, found
in all major animal groups, including:
birds,
mammals,
fish,
reptiles,
Wildebeest Connochaetes taurinus
A christmas island red
amphibians,
crossing a river in East Africa. Migration,
crab on its migration to
seemingly timed to coincide with the
insects,
lay eggs (Indian Ocean).
and crustaceans. annual pattern of rainfall and grass growth.
• The trigger for the migration may be local climate, local availability
of food, the season of the year or for mating reasons.
• To be counted as a true migration, the movement of the animals
should be an annual or seasonal occurrence, such as birds migrating
south for the winter, or a major habitat change as part of their life,
such as young Atlantic salmon leaving the river of their birth when
they have reached a few inches in size.
(Behavioral Adaptation)
Hibernation(Behavioral Adaptation)
Northern Bat hibernating in
Norway
• Hibernation is a state of inactivity and metabolic depression in
animals, characterized by lower body temperature, slower breathing,
and/or lower metabolic rate. Hibernating animals conserve energy,
especially during winter when food supplies are limited, tapping
energy reserves, body fat, at a slow rate.
Black bear mother and cubs
"denning“.
• Although often associated with cold temperatures, the root
purpose of hibernation is to conserve food during a period
when sufficient food is scarce. It is the animal's slowed
metabolic rate which leads to a reduction in body
temperature and not the other way around. Hibernation
may last several days, weeks, or months depending on
species, ambient temperature, time of year, individual
animals body condition, and fur on the animal's body.
Storage of food in a bulb
(Structural)
Shallot bulbs
• A bulb is a short stem with fleshy leaves or leaf bases. The leaves often
function as food storage organs during dormancy. Ex. onion, garlic,
lilies, tulips.
Tulip bulb and
development
• A bulb's leaf bases, known as scales, generally do not support leaves, but
contain food reserves to enable the plant to survive adverse conditions. At
the center of the bulb is a vegetative growing point or an unexpanded
flowering shoot. The base is formed by a stem, and plant growth occurs from
this basal plate. Roots emerge from the underside of the base, and new
stems and leaves from the upper side.