Chapter 10
Mollusks, Arthropods, and
Echinoderms
7th Grade Science
Mollusks
• __________
- invertebrates with soft
Mollusks
unsegmented bodies that are often protected
by a harder outer shell
• _________
- a thin layer of tissue that covers
Mantle
the internal organs – produces the hard shell
• _______
- crawling, digging, or catching prey
foot
• Examples of Mollusks – clams, snails, scallops,
oysters
Characteristics of Mollusks
• _____________
- bilateral symmetry and a
Body Structure
digestive system with __________.
Body
Two openings
parts are not repeated as in segmented
worms – instead organs are located in one
area.
• _________________
Open circulatory system - blood is not always
inside blood vessels – blood sloshes over the
organs and returns to the heart.
Obtaining oxygen
• ____
gills - mollusks that live in water obtain
oxygen through _______
and __________
cilia
Blood vessels
cilia
• _____
- hair-like structures that move back
and forth making the water flow over the gills
• Gills remove oxygen from the water and
passes it into the bloodstream
• Wastes are also removed through the ______
gills
into the water
Three Main Groups
• Mollusks are classified into three main groups
based on _______________
Physical characteristics
• Three main groups of mollusks are:
1.
2.
3.
gastropods
___________ - single external shell or no shell
__________
- two shells held together by hinges
bivalves
___________
cephalopods - ocean dwelling – foot adapted to
form tentacles around its mouth
Gastropods
•
•
•
•
___________of
mollusks
Largest group
Examples: _____________
Snails and slugs
Live nearly everywhere on earth
Some are herbivores
________, carnivores
_________, and
________
scavengers
• ________
- organ that is a flexible ribbon of
radula
tiny teeth to obtain food
• Movement – creeping along on a broad foot
_____
Bivalves
• Oysters, clams, scallops, and mussels
• Found in ________________
Water environments
• ____________
- strain their food out of water
Filter feeders
as it flows over their gills
• __________
omnivores
• Movement - _____
larva float or swim, adults
attach themselves to hard surfaces or use
foot to move slowly
their ____
Cephalopods
• Octopuses, squids, cuttlefish
• Only mollusks with a __________________
Closed circulatory system
• _________
carnivores - captures prey using muscular
tentacles.
• ________
- uses to cut the flesh of its prey
radula
• ___________
Nervous system - most complex of all invertebrates,
large eyes and excellent vision, large brains and
ability to remember learned items.
• Movement - ____________
Jet propulsion
Arthropods
arthropods
• ___________
- spider, grasshopper, crabs,
lobsters, centipedes and scorpions.
• Classified into 4 major groups:
1.
2.
3.
4.
crustaceans
__________
__________
arachnids
Centipedes and millipedes
___________________
insects
____________
Arthropods Body Structure
• Arthropods are __________
invertebrates that have:
External skeleton
– _______________
– _______________
A segmented body
Appendages - jointed attachments
– ___________
joint
“arthros” – Greek for ______
Foot or leg
“podos” – Greek for __________
– Bilateral symmetry
– ______
open circulatory system and a digestive system
Two openings
with ___________
– Reproduce sexually
Outer Skeleton
• ___________
- waterproof outer covering
exoskeleton
• Exoskeleton _________
the animal and
protects
prevents __________
Evaporation
• Arthropods occasionally shed their
exoskeleton and grow new ones that are
larger.
• __________
- the process of shedding the
molting
exoskeleton
Segmented Body
• Segmented bodies similar to an earthworm
• Easy to see segments in _________
and
centipedes
millipedes
__________.
• An arthropod may have up to three segments:
– _________
head
– _________
Mid-section
Hind section
– ___________
identical
Segments are _________
looking
Jointed Appendages
• ________
in ___________
give the animal
Joints
appendages
____________
and enable it to ________
flexibility
move
• ______________________
Appendages are highly specialized tools for moving,
eating, reproducing, and sensing the
environment
• ________
- an appendage that is attached to
antenna
head that contains sense organs.
the _____
• ____
legs and _____
wings are also appendages
Diversity
• Scientists have identified more
species of arthropods – over a
million – than all other species of
animals combined!
Crustaceans
• ___________
- shrimp, crab, and pill bugs
crustaceans
• Crustaceans thrive in ________,
freshwater ______,
oceans or
Damp places
___________
Body structure - two or three body sections,
• ___________
five or more pairs of legs, and two pairs of
antenna
oxygen - most have gills to obtain oxygen
• ______
food - scavengers, predators, herbivores
• ____
Life Cycle of Crustaceans
• Life cycle for many varieties begins as _______
larvae
• metamorphosis
______________ - a process in which an
animal’s body undergoes dramatic changes in
form during its life cycle.
• _________
develop into adults through
larvae
____________.
metamorphosis
Arachnids
• arachnids
________ - spiders, mites, ticks, and scorpions
• Arachnids are _________
with two body
arthropods
sections, four pairs of legs, and no antennae
• ____________
First body section - combined head and
midsection
• _____________
Second body section - hind section called the
________
abdomen
abdomen
• ___________
- contains the reproductive
organs and part of the digestive system.
Spiders / Mites/ Scorpions/Ticks
• All spiders are ________
predators and most eat
_______.
insects
• Adaptations include _____
fangs - used to inject
venom and sucks in food
• _______
and chiggers are parasites
_________
Mites
stinger at the end
• __________
- adaptation is a _____
scorpions
of its abdomen to inject venom into prey.
ticks
• ______
- parasites that live on the outside of
hosts bodies
Math / Analyzing Data pg. 341
Centipedes and Millipedes
arthropods
• Centipedes and millipedes are _________
with ____________
Two body sections and _____________.
Many pairs of legs
• First body section has a _____
head with one pair of
_________
antennae
• The second body section has a long
_________
with many body segments
abdomen
• ___________
have one pair of legs attached
centipedes
to each segment
Centipedes and Millipedes Continued
“ one hundred feet”
• Centipede means ______________
• Centipedes are very fast _______
predators that inject
venom into their ____.
prey
Millipedes
• ____________
- have more than 80 segments
have _____
pairs of legs on each segment.
two
“thousand feet”
• Millipede means _____________
- they do not
have that many
scavengers
• Millipedes are _________
Section 2 Assessment
• Page 342 (1 and 2)
Insects
• ________
- caterpillars, plant hoppers,
insects
dragonflies, and bees
arthropods
• Insects are ___________
with all of the
following:
Three body sections
– _________________
Six legs
– ________
One pair of antennae
– _________________
– ________________
Two pairs of wings
Body Structure
• The three body sections are:
head
– ________
- most of the insects sense organs, two
large compound eyes – keen at sensing
movement. Simple eyes distinguish between light
and darkness.
thorax - midsection where wings and legs are
– _______
attached. Insects are the only invertebrates that
can fly
– _________
abdomen - contain the internal organs
Obtaining food
• Insects feed on all of the following depending
on their specialized and adapted _________:
mouthparts
– _________________________
Parts of plants – leaves or nectar
Products that are made from plants – book lice
– __________________________________
Animal – fleas and mosquitoes feed on the blood of
– ______________________________________
living animals
Animal droppings – dung beetle
– _________________________
Decaying bodies of dead animals – burying beetles
– ______________________________________
Life Cycle
• Insects are born from tiny, hard shelled
___________
Fertilized eggs
• After they hatch, insects begin a process of
metamorphosis (either complete or gradual)
____________
before becoming an adult
_____insect.
• __________________
Complete metamorphosis - four stages
–
–
–
–
egg
_______
larvae - specialized for eating and growing
______
pupa - enclosed in a protective covering
______
_______
- beetles, butterflies, flies and ants
adult
Gradual Metamorphosis
Gradual metamorphosis - no distinct larval phase.
• ________________
• Egg hatches into a stage called a _____
nymph
nymph
• _________
- looks like an adult insect without
wings
• Grasshoppers, termites, cockroaches and
dragonflies.
Insect Ecology
• ___________
- series of events in which one
Food Chain
organism eats another and obtains energy.
• __________
- the study of food chains and
ecology
other ways that organisms interact with their
environment
sun
• All food chains begin with the ____
• Next a _________
- an organism that makes
producer
its own food – grass and other plants.
Insects and the Food Chain
• ___________
- producers are the food that
consumers
provides energy. Some consumers also eat
consumers
other _________.
• ___________
- breaks down the wastes and
decomposers
dead bodies of other organisms
• Insects can either be _________
or _________
consumers
decomposers
in the food chain
• Insects can be ______
for other consumers
prey
Insects as Consumers, Prey, and
Decomposers
20% of the crops grown by
• Insects eat about ____
humans as well as wild plants.
consume plant materials
– Caterpillars ________
prey
– Caterpillars and other insects are _______
for
other types of animals such as birds and fish.
decomposers
– Insects such as the carrion beetle are __________
- feed on the tissues of dead birds.
Pollen and Disease Carriers
• _________
- an animal that carries pollen
pollinators
among plants. Examples of insects as
Bees, beetles, and flies
pollinators are _______________.
• Without pollinators some plants would not be
able to _________
reproduce
• Insects that carry diseases often have
Sucking mouth parts that pierce the skin of their
______________
prey that provides an opening for the disease
malaria
to enter the organisms body - ______
Controlling Pests
pesticides
• _________
- use of chemicals to control pests
• Pesticides have also killed _________
pollinators
traps and other
• Humans have also used ____
Living things (such as other insects) to control
__________
pests.
Biological control
• _______________
- a natural predator or
disease released into an are to fight a harmful
insect.
Echinoderms
Echinoderms
• _____________
- invertebrates with an
internal skeleton and a system of fluid filled
tubes.
• All echinoderms live in ________
Salt water
• The internal skeleton of the echinoderms is
called an __________
Endoskeleton - made up of hard
plates which give the animal a bumpy texture.
• ______________
Radialy symmetrical usually in multiples of 5
Movement
Water vascular system
• _________________
- the internal system of
fluid-filled tubes
• The water vascular system contracts and
forces water into the _______
Tube feet - the ends of
the tube feet are sticky and they act like
suction cups.
suction
• The ________
allow the
stickiness and __________
echinoderms to grip the surface beneath them
Reproduction and Life Cycle
eggs are usually fertilized in the ______
water
• _____
• Fertilized egg develops into a swimming
______
.
larvae
larvae undergo ___________
metamorphosis and become
• ______
______
echinoderms.
adult
• 4 major groups of echinoderms:
__________,
__________,
_________,
Sea stars
Brittle Stars
Sea Urchins
Sea Cucumbers
__________