Teacher's Section: Adaptation Unit

Adaptation Unit

Introduction

All living organisms exhibit varying capabilities to survive during changing environmental conditions. These abilities to survive, or adaptations, enable an organism to obtain sufficient resources so that they might survive long enough to reproduce. Adaptations fall into the following three categories:

1. Adaptations to accommodate the physical environment

2. Adaptations to secure food and avoid being eaten

3. Adaptations to ensure successful reproduction.

This three-week unit will allow students to come up with problems that marine organisms might have with their environment and the adaptations that they have that allow them to overcome those problems.

Objectives

list why organisms must have adaptations.

describe the different methods of how organisms adapt to accommodate their physical environment.

describe the different methods of how organisms adapt to avoid being eaten and to secure food.

describe the different methods of how organisms ensure successful reproduction.

Adaptation Unit Student Activities

Days One and Two

have a large group class discussion after the teacher lectures on the need to adapt. During the discussion, have the students generate a list of adaptations organisms might have in the three categories from the lecture (listed in the introduction above). Divide class into enough groups to cover the list, maybe giving each group two or three adaptations to research within the same category. Their task is to research the adaptations and to produce a skit or a video to teach the class about their assigned adaptations.

Days Three-Five

allow the students to do research and to produce their skit or video.

Day Six (after a weekend)

present the skits or videos to the class. The group must also provide a one-page handout summarizing their information to the class.

Days Seven-Fifteen

Allow the students to do the diving learning cycle. They will present their results to the class and write up their results in a lab report. Follow up with a teacher lecture on the adaptations of mammalian diving (and other mammalian adaptations not yet addressed).

Over the entire time frame of the unit I also have the students do an activity that I got from another teacher named Kate Braceland, who also graduated from the U of A masters program. It is a great activity that examines the necessary adaptations to survive in the intertidal. The student is given an organism name and they must do research. Once they have enough information, they must build a scale model of the organism and discuss what types of stresses it must overcome and how it has adapted in order to survive. My version of this activity is included.

Adaptation Notes

Introduction

1. attributes of life can be defined as four "R’s": respiration, reproduction, response and regulation

2. three needs to adapt (survival of the "fitter")

accommodate physical environment.
secure food and avoid being eaten.
ensure successful reproduction.

Salinity Effects

1. constant regulation needed in salt water.
2. sea cucumber example.

maintains internal salts in tissues isotonic to that of environment.
will die if placed in (hypotonic) freshwater.
cannot withstand major salinity fluctuations.

bony fish example
withstand varying salinities due to osmoregulatory mechanisms
must always expend energy to maintain homeostasis
in hypertonic situations to offset osmotic loss, produce small quantities of salty urine, drink lots of seawater and excess salt excreted by gills.
In hypotonic situations to offset osmotic gain, produce large volumes of dilute urine, do not drink and salt absorbed by gills.

Temperature Effects

1. metabolism proceeds at temperature-regulated rates

2. ectotherms (NOT "cold-blooded")

external conditions govern body temperature
marine ectotherms have optimum temperature ranges
for many, metabolism rates may double if temperature is raised 10° C.

3. endotherms (birds and mammals only)

maintain about 40° C body temperature by release of heat in internal tissues not restricted by environmental temperatures, thus a wide range of niches

4. large tunas, bill fishes and sharks are intermediates (Ch. 11)

Diving Effects

1. During dives, many marine mammals can overcome duration…

a. problems

exhale before diving!

larger lung capacity, hemoglobin count and blood volume cannot account for long duration dives lowering metabolic rate to just resting still doesn’t account for long dives.

b. solutions

metabolic rate lowered to below resting rate by shutting down non-essential organ systems. Blood is shunted away from these organs and rationed to critical organs, such as brains, lungs and heart. Bradycardia (lowering of heart rate) occurs—no need for high cardiac output.

1.and depth.

a. Problems

every 10m of depth is 1 additional atm of pressure.

brings about problems with maintaining equilibria between ambient pressure within air-filled spaces, causing edema, capillary rupture and air embolism (bubbles forced into the blood)

brings about problems due to increased solubility of gases, causing nitrogen narcosis (large amounts of nitrogen in the blood adversely affects brain function), and "the bends" (decompression upon quick ascent does not allow large volume of gases to leave blood, resulting in the obstruction of capillaries by gas bubbles).

b. Solutions

no sinuses in skull and specialized blood vessels in middle ear to expand at increased depths. No pressure differences between air-filled spaces.

compressible thorax, allowing lungs and alveoli to collapse, therefore no residual lung volume. No gas exchange can occur.

Multitudes of other adaptations

mimicry, camouflage, symbiosis, parasitism, etc.