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| Dallas Zoological Society Partnership : Elementary Hard and Soft Animals |
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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 on planet Earth. The tiniest creatures have only one cell. The largest creatures such as elephants and whales roam the land and swim in the oceans. Human beings are the smartest animals of all.
The soft, jelly-like animals that live on land and in the sea are called mollusks. Octopuses and squid are called cephalopods. Sea stars and sea urchins have spiny skins; they are called echinoderms. The largest group of animals on the Earth is the arthropod group. They include insects and spiders. Scenario As you lie in the grass, you watch 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
Echinoderms – The Spiny Animals!
http://www.oceanicresearch.org/education/wonders/echinoderm.html Conclusion & Project
Conclusion Mollusks, worms, echinoderms, and arthropods are all amazing animals. The mollusks have soft bodies and 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 have spiny skins and can grow back any of their body parts. Arthropods are the largest group of all animals. Insects live everywhere on Earth. They have six legs. Spiders have eight legs and lobsters have ten or more legs.
Scenario Mollusks, worms, arthropods, and echinoderms are very interesting. Write a brief story and include each type of animal.
Glossary
bivalve - mollusk that contains two shells
univalve - mollusk that contains only one shell
carnivore - an animal that eats flesh or meat
predator - an animal that eats other animals
prey - an animal that is hunted and eaten by another animal
regenerate - to replace (a lost or damaged organ or part) by formation of new tissue
diverse - animals that differ from one another
symmetrical - equal parts that extend from the center; the sea star has five even arms that all come from the same cenral point
podio - tube feet; used for suction, eating and movement
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
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
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