|
SURVIVING THE RACE: A SEA TURTLE DILEMMA
MASTER TEACHER Andrea Cantu
GRADES 6 - 8
OVERVIEW
This lesson provides students with an in-depth understanding of
the predator-prey relationship. During the lesson students will record the
differences between sea turtles and land tortoises. The lesson will use
video to show how adult olive ridley sea turtles, their eggs, and hatchlings are
in constant danger from predators.
ETV SERIES
Kratts' Creatures: #126 Arribada I: The Sea Turtle
Invasion
Kratts' Creatures: #127 Arribada II: Running the
Gauntlet
LEARNING OBJECTIVES
Students will be able to:
*differentiate between a sea turtle and a tortoise.
*make inferences about the effects of predation on sea turtle
populations.
*hypothesize as to why the olive ridley selects the same nesting
beach from which it was hatched to lay its eggs.
*make a food web to understand how the arribada supports other
animals' existence.
*make recommendations for ways to minimize the factors which
contribute to the possible extinction of sea turtles.
MATERIALS
* centimeter graph paper (one per student)
* activity sheets (one per student)
* internet access for every group of three students
* string (12-16 inch piece for each of the cards below and wrap
the remaining string into a ball to form the web
in the food web activity)
* card stock printed with the names of the predators and prey
mentioned in the videos. [13 predators (black crowned night heron, wood stork,
raccoon, ghost crab, coati, frigate bird, black vulture, fungus, coyote, shark,
crocodile, jaguar, and man), 2 adult turtles, 8 eggs, 4 hatchlings, and 3 algae
cards]
VOCABULARY
Arribada - the mass nesting of olive ridleys or Kemp's ridleys.
Hatchlings - baby sea turtles.
Predator - an animal that hunts another animal for food.
Prey - any animal hunted or killed by another animal for food.
Imprint - to fix firmly in the memory.
Food web - interconnecting food chains.
PRE-VIEWING ACTIVITIES
Pass out worksheets to students. (Note that worksheet activities
and questions are numbered through out pre-viewing, viewing, and post viewing
periods.) Looking at worksheet -#1 Check for prior knowledge by having
students draw a sea turtle to scale given the length of the turtles' shell.
This activity will help students to better understand the different body design
dynamics that enable a sea turtle to exist in its habitat. Pass out a half
sheet of centimeter graph paper to every student. Have students decide
what scale they will use to make their drawings (ie 1cm = 10cm). After
making their drawings, have students go the Euro Turtle website to see how close
they were to the actual body shape. Discuss the sea turtles body shape and
how this design is beneficial to living in its environment. Divide the class in
half. Have each group of students create a human graph (individual
students will line up to represent the units of the graph) comparing the size of
and average middle school student* to the average size of an olive ridley (70cm)
and Kemp's ridley (67 cm) sea turtles. (* To find the average size student
in your class, line students up against the wall in order of height.
Select the student that is the median.)
FOCUS FOR VIEWING
To give a student a specific responsibility while viewing say,
"In Arribada I, you are about to see a nesting behavior of sea turtles that
is exhibited by only two species in the world. The introduction of the
show will give you a brief overview."
VIEWING ACTIVITIES
Looking at worksheet #2, say, "What is a predator? (an
animal that hunts another animal for food) What is prey? (an animal
hunted by another animal). Watch the video to see the predators of the
olive ridleys. Listen for the meaning of the word arribada."
Begin tape where the Kratts are on the beach; audio is "Hey Martin do you
got the list?" Pause the tape when an olive ridley turtle
is crawling on the beach. Audio is "They are taking the beach by
storm." Looking at worksheet #3, . ask the students to name some
predators of ridleys they saw in the video clip. (black crownd night herons,
wood storks, raccoons, ghost crabs, coatis, frigate birds, and black vultures)
Go on to ask what is an arribada. (the mass arrival of sea turtles to nest.)
Fast forward the tape through to where the video is the title:
Arribada I "The Sea Turtle Invasion". The background is waves crashing
on the beach.; audio is music. Pause the tape. Ask students to look
or listen for predators not mentioned previously. (fungus, coyote)
Resume the tape. Pause where the video is a cartoon frame with a question
mark in the center. Audio is "What makes a sea turtle a turtle."
Looking at worksheet # 4. ask students to name the two species of turtles
which have arribadas. (olive and ridley). Ask students to listen to find
out how turtle and tortoises are different. Resume the tape. Pause
the tape when the video is Chris Kratt with flying
cartoon wings. Audio is "Not all turtles are sea bound".
Say, "Sea turtles and tortoises are both reptiles let's see how they
differ". Looking at worksheet question #5, ask students to list
characteristics of a tortoise (habitat is land, legs are short, dome shaped
bodies, retractable head) and a sea turtle (habitat is the sea, flippers instead
of legs, body is streamlined, nonretractable head). Resume the tape.
Pause the tape when the video is Chris Kraft (red shirt) is sitting on the
ground in the jungle. A coati walks past Chris; audio is "All we can
do is be patient and wait." Review differing characteristics of a sea
turtle and tortoise. Say, "In the next segment you will learn what
conditions are necessary for an arribada to occur. Record your answers on
worksheet # 6." (rising tide, strong on shore winds, between the
months of August and December, a few days before the first quarter or last
quarter moon, and maybe chemistry) Resume the tape. Pause the tape
when the video is Allison pointing with a tv remote. Audio is "The
guys are up to their knees in sea turtles this very.......minute."
Review the arribada conditions. Discuss arribada conditions.
Fast forward the tape where the video is Allison using an adding
machine; audio is "Okay, something is obviously wrong." Pause
the tape. Ask students to watch for other predators the sea turtle faces
not previously mentioned. Have students continue to record answers on worksheet
question #3. (shark, crocodile, jaguar) Resume the tape. Pause
the tape when the video is Allison sitting at a desk. Audio is Allison
saying "Turtle moms are the most dedicated mothers." Say,
"Before we show the next video clip, go back to question #3 and place a
check mark next to the predator under the column titled "Adult" for
those predators that eat adult sea turtles". Fast forward the tape
through to where the Kratts are coming through tall grass. Audio is
"Yeah, mission accomplished" Pause the tape. Say,
"Watch and listen to why it is difficult for a female ridley to move on
land, (The female has to drag her body across the land.) and how the female
prepares her nest (locate a place above the high tide line, scup out a vase
shaped hole to lay eggs in, fill hole and packs down the sand, throws sand
around to hide the nest from predators). Have students listen and watch
for two pieces of information. Worksheet question #7. How many eggs
does a turtle lay? (100) Worksheet question #8. What time of the day does the
arribada occurs? (after dark when the sun is down) Resume the tape.
Stop the video when the baby turtle crawls towards the ocean as the waves roll
in. Audio is "The babies will be running the gauntlet in the next
episode of Kratts' Creatures. Review questions mentioned in this section.
FOCUS FOR VIEWING
Say, "In Arribada I you saw the difficulties the adult sea
turtles faced. In Arribada II, you will see what obstacles the baby
turtles have to overcome to get to the sea."
VIEWING ACTIVITIES
Say, "For worksheet question #9, listen for the four
activities that the baby sea turtles have to do to make it to the ocean (hatch,
dig out of the nest, crawl to the ocean, make it past the predators).
Begin the second video where the title is: Arribada II Running the Gauntlet, the
background shows the beach; audio is music. Pause the tape when Martin is
looking through binoculars; audio is music. Review question #9. Say
"At this point you have 12 of the 13 predators listed. Through out
the video watch what other life stage of the sea turtle that the predators eat.
Place check marks in the appropriate columns". Resume the tape. Pause
the tape when Allison is at the bookcase getting a book; audio is Allison saying
"I am talking about tiny sea turtles and little eggs they don't have any
defenses". Ask students to answer worksheet question #10, "How
many days of food does a turtle egg provide"? (50 days of food)
Tell students that baby sea turtles are called hatchlings. Resume
the tape. Pause when the cartoon section showing a turtle within an egg.
Audio is "And you got 50 days count them, 50 days of food packed in there.
Review predator and prey concepts.
Fast Forward the tape where the video is coati on the beach with
black vultures.
Audio is "It looks like these coatis have found something
that does not move at all. Pause the tape. Say, "Watch to
see how vultures and coatis help one another?" (Coatis dig up the
eggs and the vultures eat the scraps. The vultures warn the coatis of
approaching predators.) Resume the tape. Pause the video when the
jaguar walks back into the jungle. The audio is music. Discuss how
the vultures and coatis benefit each other.
Fast Forward the tape where 3 raccoons appear on a grassy area;
audio is "Twenty raccoons can destroy every single nest that was made in a
night. Pause the tape. Say, "Watch for the following: What are some
of the predators mentioned so far that eat turtle eggs"? (coatis, black
vultures, raccoons, coyotes, ghost crabs, and fungus) Put a star by the
predator that causes the most damage. (ghost crabs) What is the last
predator of the sea turtles?" (man) Resume the tape. Pause the
video where Allison is looking at a screen with flying frigatebirds. She
says "I mean its just not when they're eggs. When they hatch they struggle
too." Say, "In the video you saw man collecting large bags of
sea turtle eggs. Can man collect as many eggs as he wants? (no) Why
not?" (It could cause the turtles to become extinct.) For the
internet users, say, " In the internet activity, after the video and food
web activity, you will find out what the Costa Rican government has done to
protect the turtle eggs." Fast Forward the tape when Martin is laying
on his stomach on the beach. Audio is "Each baby sea turtle has a
whole nest of other baby sea turtles to help it out". Pause the tape.
Say, "after the hatchling digs to the surface, listen and watch what the
babies have to do before they begin to crawl. You will see that the
hatchlings have more obstacles to face other than predators." Resume
the tape. Pause the tape when a black vulture eating a baby turtle appears on
Allison's wall screen; audio is music and then Allison says "Guys I have
got it." Ask the following questions for oral answers. "What
must the hatchlings do before it crawls to the sea? (wipes its eyes, gets it
bearing, heads toward the light) What can stop a hatchling from reaching
the sea?" (predators, fishing line and rope) "Make a
hypothesis as to the percentage of eggs laid that will have hatchlings making
it past the predators." Record their answers on the board.
Fast Forward the tape when Martin is taking a sea turtle to the
water. Audio is "The flying sea turtle. Let's go buddy."
Pause the tape. Looking at worksheet question # 11, say, "Listen for the
meaning of the word imprint" (a memory) Looking at worksheet
question 11, ask, "Why must a hatchling crawl across the beach? (to
imprint, to get its heart and lungs pumping) Resume the tape. Stop
the video after Allison is writing in her journal. Audio is "We can
watch and wonder and keep exploring." Using the statistics that Ttark
gave, let's do some turtle math, question #13. Ask students to compare their
hypothesis, hatchlings making it past the predators, to the actual percentage
given in worksheet question #13.
POST VIEWING ACTIVITIES
Say, "We saw the predators of the olive ridley sea turtle.
We are going to make a food web using the predators seen in the video and the
three stages in the sea turtles life (adult, egg, hatchling). Each of you
will have one of the following tags with a predator, stage in a turtles life, or
a plant written on it. Everyone will stand in a big circle. Olive
ridleys are generally carnivores, but in one part of the world they eat mainly
algae. We will begin the activity with the algae. (Student with the
algae tag will hold an end of the string.) What will eat the algae? (adult
sea turtle) (While holding onto the string end, the student with the algae
card will pass the ball of string to a person who has the adult sea turtle tag.)
At this point the person with the sea turtle card and the string can decide if
they will pass the string on to its predator or to what it eats. Continue
this process until all of you are holding a string. Keep your strings
tight. What does the string going back and forth resemble? (a web.)
What would happen to the food web if turtles were over hunted or died from
pollution? (the web would collapse.) Let's see what would happen.
(Pick a student with an adult turtle tag and have the student drop their line.)
As soon as you feel your line get loose drop your line." ( The web
will collapse rapidly.)
Say, "The videos stressed that nature left alone, can
take care of itself. The following internet search activity will give you
more information on olive and Kemp's ridley turtles and how man has influenced
the fate of these creatures. Search the websites to find answer worksheet
questions to14-18."
ACTION PLAN
1. Have the outreach program from the Texas State Aquarium
give a presentation on sea turtles.
2. Borrow the Endangered Species Trunk from the Texas Parks and
Wildlife.
3. Have students tell about the arribada in the sea
turtles point of view.
4. Have students create original riddles or songs about sea
turtles or the arribada.
5. Have students create their own internet scavenger hunt.
EXTENSIONS
Mathematics
Create more questions similar to activity sheet questions #13
and #14 but use different species of sea turtle statistics.
Art
Create a diorama of the arribada.
Social Studies
Research the myths about eating turtle eggs. Find out how
sea turtles are viewed culturally. Have students plot on a map the six
nesting sites of the olive ridley.
Reading
Read stories about myths and legends relating to sea turtles.
Turtle Worksheet
Pre-viewing Activities
1. Draw an olive ridley sea turtle. (Its shell averages 68cm in
length)
(adhere drawing on graph paper to the space provided above)
Refer to the Euro Turtle website for more information about
olive ridleys http://www.exeter.ac.uk/telematics/EuroTurtle/olive.htm
2. Define the following terms.
a. predator -
_________________________________________________________
b. prey -
_____________________________________________________________
c. arribada -
__________________________________________________________
3. List the predators of the olive ridley. Check the column
that represents the stage of the turtles life cycle that each of the following
predators eat.
Predator Adult Eggs Babies
a. ____________________________________________________________
b.__________________________________________________________
c.__________________________________________________________
d.__________________________________________________________
e.__________________________________________________________
f.__________________________________________________________
g.__________________________________________________________
h.__________________________________________________________
i.___________________________________________________________
j.__________________________________________________________
k.__________________________________________________________
l. ___________________________________________________________
m._____________________________________________________
4. Name the two species of sea turtles which have arribadas.
_____________________
5. Record the appropriate information about sea turtles and
tortoise in the columns below.
Sea Turtle Tortoise
a. Habitat
_______________________________________________________
b. Appendages
_______________________________________________________
c. Movement
_______________________________________________________
d. Body shape
_______________________________________________________
e. Retracts into shell
___________________________________________________
6. List the conditions for an arribada to occur.
a._____________________________________________________
b._____________________________________________________
c._____________________________________________________
d._____________________________________________________
7. How many eggs does an olive ridley lay? _________
8. What time of the day does the arribada occur?
_________
9. What do the baby sea turtles have to do to make it to the
sea?
a._____________________________________________________
b._____________________________________________________
c._____________________________________________________
d._____________________________________________________
10. How many days of food does a turtle egg provide?
___________________________
11. Define imprint.
_____________________________________________________
12. Why must a hatchling crawl across the beach?
a.______________________________________________________
b.______________________________________________________
Turtle Math
13. You have 4 million eggs. Find out the number of eggs
which are:
a. dug up by other turtles (7%) ___________
b. do not hatch (50%) __________
c. are eaten by predators (13%) _________
d. are untouched (30%) __________
Internet Search
14. Refer to http://www.gema.com/ostional/faqs.html
a. What percent of hatchlings survive to the adult
stage? _____
b. Out of 4 million eggs how many will make it to
the adult stage? ____________
c. How long do they estimate that it will take for
an olive ridley to mature? _________
15. Refer to http://www.exeter.ac.uk/telematics/EuroTurtle/olive.htm
(Hint: look under the category of
sex determination.)
a. What temperature yields a 1:1 ratio of males to
females? _______
b. From your answer in 14b. How many turtles
will return to nest? __________
c. What incubation temperature will produce mainly
males? _________
16. Refer to this website: http://abcnews.go.com/sections/science/DailyNews/turtleeggs981229.html
a. What steps have the Costa Rican government taken
to protect the olive ridley and at the same time satisfy
the Costa Rican people? ___________________________________
___________________________________________________________
b. The Kratt's Creatures' Arribada videos were
filmed at Nancite beach. Name the one other nesting
olive ridleys' beach in Costa Rica. ______________________________
c. What is the number of olive ridley
arribada sites in the world? _________________
d. Where is the largest nesting site?
_______________________________________
17. The most endangered sea turtle, the Kemp's ridley, does
not have the large numbers of nesting females as its close cousin the
olive ridley. Refer to these websites.
http://www.turtles.org/ridleyd.htm and
http://www.mdsg.umd.edu/seagrantmediacenter/news/txpadre.html
a. In Mexico in 1947, how many Kemp's Ridleys were
nesting? ________________
b. In 1994, what was the number of nesting turtles?
________________
c. Name a nesting site in Texas.
__________________
d. How many nests were found on the above site?
__________
18. Using the internet site on question 17 and
http://members.tripod.com/~sstcn/Ridley.htm
find out what activities man has done to threaten the existence
of the olive and Kemp's ridleys. Name the three major threats for
each species.
a. Olive ridley
_________________________________________________________
b. Kemp's ridley
_______________________________________________________
c. How can man minimize these threats?
_____________________________________
__________________________________________________________
Updated: April 01, 2008
|
