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| Dallas Zoological Society Partnership : Middle School Lessons Worms, Mollusks, and More |
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Topic Overview
Quick Facts
Mollusk
evolution began more than 500 million years ago, during the Cambrian period.
A deep-sea clam found in the North
Atlantic takes up to 100 years to grow to a length of one
centimeter.
Oysters can change their sex from male to female
to male and so on, throughout their lives.
Cone shells, a gastropod, carry fast-acting
neurotoxic venom. There are several species of mollusk that are capable of
killing humans.
Because they are unable to move and feed by filtering
particles from the water, mussels and oysters can accumulate certain types of
chemicals. In several countries samples of mussels and oysters are regularly
collected to monitor ocean pollution.
Charles Darwin spent 39 years studying
earthworms more than 100 years ago.
The
Australian Gippsland Earthworm grows to 12 feet long and can weigh 1-1/2
pounds.
Some earthworms can live over 10 years.
Worms
can eat their own weight in a single day.
Because of their appetite for shell fish, sea
stars are perceived as a threat by commercial fisheries, particularly those
that harvest clams, mussels, and oysters. Sea stars are known to get into
these commercial shellfish beds and devour them entirely.
A seastar can asexually reproduce to become TWO
seastars; they can do this in two ways: autotomy or fission.
Begin the Lesson
Whole Class Introduction to the Lesson
You will need at least one computer with Internet connectivity
and a projection device, a classroom with more than one computer, or access to
a computer lab.
For this introduction and activity you will need approximately
10 minutes.
Introduce students to the mollusk and echinoderm phylum by
showing the video, “Abalone Escape Response When Presented with the Sea Star” http://www.racerocks.com/racerock/archives/vidabescape2a.htm
Sample Questions
Describe the physical features of the abalone.
Describe the physical features of the sun star.
How does the abalone know that the sun star is
present?
Why does the sun star have an advantage over the
abalone?
What did the abalone do to defend itself?
As part of the introduction, you may want to review some of the
glossary terms in advance of students going online. At this point you can launch
the WebLesson as whole-class activity using a projection device, or you can
assign students to work individually or in teams in a computer lab.
WebLesson Sites
Introduction There are millions of animals from tiny, single-celled creatures such as amoebae to the most complex the human being. There are amazing and fascinating organisms all over the Earth. They have many different body types, they behave in strange ways, and they live everywhere on the planet. Just think of all of the interesting animals that are still waiting to be discovered.
Mollusks are soft, jelly-like animals of the sea and land. They come in every shape and color and many even include a shell. Cephalopods are remarkable creatures of the sea that use a variety of methods to move, eat, and protect themselves. They are very smart animals. The spiny sea creatures with arms or rays that extend from their center are the echinoderms. They creep along the sea bottom and have strong water vascular and muscular systems that help them to eat and defend themselves. Arthropods are the largest group of animals on the Earth. They live in every climate and environment. Their segmented legs and bodies and tough outer skeletons help them to survive the harsh surroundings. Scenario As you lie in the grass basking in the warm sun, you notice an earthworm and a snail slowly creeping past. You use your magnifying glass to look closer. These organisms are certainly busy and they have very busy jobs. You walk home so that you can look up these creatures to find out more about them on the Internet.
Lesson Pages
Octopus escaping through a 1-inch hole
http://video.google.com/videoplay?docid=4007016107763801953&q=octopus Rich Media
Echinoderms – The Spiny Animals!
http://www.oceanicresearch.org/education/wonders/echinoderm.html
The Shape of Life
http://www.pbs.org/kcet/shapeoflife/video/tv_high.html?ep_ulti_explo2_mov_hi Rich Media
Conclusion & Project
Content Mollusks, worms, echinoderms, and arthropods make up the most remarkable and fascinating groups of animals on Earth. The soft-bodied mollusks grow beautiful shells to protect themselves. Humans use the shells in many ways. Worms are more than just slithery, slimy creatures. They are able to perform amazing jobs such as creating air in the soil and breaking down garbage. Echinoderms are remarkable organisms that can regenerate any of their body parts. Arthropods are the largest group of all animals. They include the tiny insects that we observe everywhere, the eight-legged spiders and crabs, and the ten and more-legged sea animals such as lobsters and shrimp. This immense group of animals offers many surprises in their body structures and their behavior patterns.
Scenario You are amazed at just how interesting mollusks, worms, arthropods, and echinoderms are. Write a brief description of each that you can present to your friends so that they will be able to understand the tiny creatures that live on the land and in the sea around us.
Glossary
nudibranch - mollusk that lives in the water and is often brightly colored and does not have a shell
bivalve - mollusk that contains two shells
univalve - mollusk that contains only one shell
cephalopod - means “head-foot”; fast-moving carnivorous mollusks that use tentacles to help in capturing food; they propel themselves through the water by flushing water through their tube-like organ called the hyponome
gastropod - means “stomach-foot”; slow-moving mollusks that have a strong, muscular foot to aid in moving around
cuttlebone - internal shell found in some cuttlefish
pen - smaller internal shell found in some squid
predator - an animal that eats other animals
prey - an animal that is hunted and eaten by another animal
carnivore - an animal that eats flesh or meat
mantle - muscular swimming organ that is uses jet propulsion to move the animal forward
contract - shrink or become temporarily smaller
hermaphrodite - an organism that is both female and male during its life
regenerate - to replace (a lost or damaged organ or part) by formation of new tissue
aboral - the side of a radially symmetrical animal that does not contain the mouth
ventral - the abdomen side of an animal; contains the mouth
podio - tube feet; used for suction, eating and movement
water vascular system - a system of water filled canals and arms that is used in locomotion, reproducing and feeding
asteroid - star shaped animal
ambulacral groove - grooves located on the underside of each appendage on the sea star that contain tube feet and are a part of the water vascular system
cilia - a microscopic hair like process extending from the surface of a cell or unicellular organism; capable of rhythmical motion, it acts in unison with other such structures to bring about the movement of the cell or of the surrounding medium
insect - small arthropods that are born as larvae and then as adults have three pairs of segmented legs and a body divided into three regions
arachnid - arthropods with four pairs of segmented legs and a body that is divided into two regions
crusteacean - marine arthropods that have a segmented body, a chitinous exoskeleton, and paired, jointed limbs
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