Download Mollusks, Arthropods, and Echinoderms

Mollusks, Arthropods, and
Echinoderms
Ms. Cushman
7th Grade General Science
November 16, 2015
Bell Ringer
• What seafood have you tried or do you know
about? Make a list.
What are the main characteristics
of mollusks?
Characteristics of Mollusks
• In addition to a soft body often covered by a
shell, a mollusk has a thin layer of tissue called
a mantle that covers its internal organs, and
an organ called a foot.
• Body Structure: bilateral symmetry, two
opening digestive system, centralized organs
• Circulatory System: Open
• Obtaining Oxygen: Gills
What are the three kinds of
mollusks?
Gastropods: Snails and Slugs
• Gastropods have a single external shell or no
shell at all
• Obtaining food: Can be herbivores or
carnivores, uses a radula (READ pg 42)
• Movement: Creeps along on a broad foot
creating and leaving a trail of mucus
Bivalves – Oysters, Clams, Scallops,
and Mussels
• Bivalves are mollusks that have two shells held
together by hinges and strong muscles.
• Obtaining food: most are filter feeders and
omnivores
• Movement: They move slowly and may attach
themselves to a solid surface during
adulthood.
• Protection: Some form pearls around sand
that would otherwise be an irritant
Cephalopods – Octopuses, squids,
nautiluses, and cuttlefish.
• A cephalopod is an ocean dwelling mollusk
whose foot is adapted to form tentacles
around its mouth.
• Obtaining food: Carnivores, captures prey
with tentacles, crushes it in a beak, and then
scrapes and cuts it with a radula (Read 44-45)
• Nervous system: excellent vision, large brain,
can learn
• Movement: swim by jet propulsion
What are the main characteristics
of mollusks?
What are the three kinds of
mollusks?
Bell Ringer
• Compare similarities between some sea
creatures and insects. Do any look similar in
appearance? Do any function similarly?
What are the four major groups of
arthropods and what are their
characteristics?
How many species of arthropods
have been discovered?
Characteristics of Arthropods
• Arthropods are invertebrates that have an
external skeleton, a segmented body, and
jointed appendages
• Outer Skeleton – a waxy covering called an
exoskeleton that sheds as the animal grows
and then is replaced by a new one.
• Segmented Body – may be divided in up to
three sections: head, midsection, hind section
Characteristics of Arthropods
• Jointed Appendages: highly specialized tools
for moving, obtaining food, reproducing, and
sensing the environment
• Diversity – Scientists have identified more
species of arthropods – over one million –
than all other species of animals combined
Crustaceans: Lobster, Crab, Shrimp,
Crayfish
• Body structure: has two or three body
sections, five or more pairs of legs, and two
pairs of antennae
• Obtaining oxygen: most live in water and have
gills
• Obtaining Food: They are scavengers or
predators
• Life cycle: starts as swimming larva – goes
through metamorphosis
Arachnids
• Body Structure: Two body sections, four pairs
of legs, not antennae. Abdomen is the hind
section for digestion and reproduction
• Read pg 52-53
• Spiders
• Mites
• Scorpions
• Ticks
Centipedes and Millipedes
• Body Structure: Two body sections, many
pairs of legs
• Centipedes - “hundred feet” one pair of legs
per segment.
• Millipedes – “thousand feet” two pair of legs
per segment
– These don’t necessarily have that exact number of
feet but may be close one way or another.
Which one
is a
millipede
and which
one is a
centipede?
How do arthropod groups differ?
• Draw Figure 10 on page 49.
• Draw Figure 11 on page 50.
What are the four major groups of
arthropods and what are their
characteristics?
Bell Ringer
• Draw figure 17 on page 56
What are the three main
characteristics of insects?
Body Structure
• Three body sections, uses a system of tubes to
get oxygen, six legs, one pair of antennae, and
usually one or two pairs of wings, most are
camouflaged to avoid predators
• HEAD – location of sense organs like antennae
and compound eyes and simple eyes
• THORAX – midsection where wings and legs
are attached
• ABDOMEN – houses internal organs
What is one way insects are
adapted to obtain particular types
of food?
Obtaining Food
• An insect’s mouthparts are adapted for a
highly specific way of getting food.
– Sponge like mouthpart
– Coiled tube like straw
– Sharp-edged mouthparts
• Look at Figure 18 on page 57
What are two types of
metamorphosis that insects
undergo?
Life Cycle
• Each insect species undergoes either complete
metamorphosis or gradual metamorphosis
• Complete Metamorphosis – four different stages:
egg, larva (for growing and eating), pupa, and
adult (beetles, butterflies, flies, and ants)
• Gradual Metamorphosis – An egg hatches a
nymph and it grows into an adult (grasshoppers,
termites, cockroaches, and dragonflies)
Complete Metamorphosis
Gradual Metamorphosis
Let’s Review
• What are the three main characteristics of
insects?
• What is one way insects are adapted to obtain
particular types of food?
• What are two types of metamorphosis that
insects undergo?
Let’s Draw
• Complete and Gradual Metamorphosis
• Figure 19 on pages 58-59
Bell Ringer
• Would the world be better off without
insects? Why or why not?
Why are insects important in food
chains?
What is a food chain?
Insects and the Food Chain
• PRODUCER – makes its own food (a plant)
• CONSUMER – eats other organisms
• DECOMPOSER - breaks down wastes and dead
bodies
• Insects could be CONSUMERS or
DECOMPOSERS. They play a key role in the
food chain.
Insects as Consumers of Plants
• Insects play key roles in food chains because
of the many different ways that they obtain
food and then become food for other animals.
• Insects eat 20% of the crops grown for
humans and wild plants too.
Insects as Prey
• The main source for trout and bass is insects
• A single swallow chick can eat 200,000 insects
before it leaves the nest.
Insects as Decomposers
• Insects breakdown decaying matter, expose
soil to oxygen and nutrients, and clean up
waste materials.
Insects as Food for Humans (Eww)
• Read page 65.
• (I was going to insert a photo of a chocolate
covered bug, but I just couldn’t. I just
couldn’t.)
What are two other ways insects
interact with their environment?
Pollen Carriers
• Bees are pollinators and so are many beetles
and flies. Without pollinators, some plants
cannot reproduce.
What plants need bees?
Disease Carriers
• Mosquitos, fleas, and ticks
• Malaria, Yellow Fever
• The Plague
• Lyme’s Disease, Rocky Mountain Spotted Tick
Fever
What are some ways used to
control insect pests?
Controlling Pests
• To try to control pests, people use chemicals,
traps, and living things, including other
insects.
• Traps
• Plants that aren’t attractive to pests
• Biological Controls – predators or diseases
that effect only the pest.
Why are insects important in food
chains?
What are two other ways insects
interact with their environment?
What are some ways used to control
insect pests?
What are the main characteristics
of echinoderms?
Echinoderms: Sea Cucumbers, Sea
Stars, Sea Urchins, Sand Dollars
• Invertebrates with an internal skeleton and a
system of fluid-filled tubes called a water
vascular system
• They all live in salt water
• Body structure: Endoskeleton, body parts
(usually five) are arranged like spokes on a
wheel. They have radial symmetry
Echinoderms: Sea Cucumbers, Sea
Stars, Sea Urchins, Sand Dollars
• Movement: they use tube feet to move slowly
and their water vascular system to capture
food.
• Reproduction and Life Cycle: Eggs are
fertilized in the water and grow into tiny
swimming larva that eventually develop into
adults.
What are the major groups of
echinoderms?
Diversity of Echinoderms
• Sea Stars
Diversity of Echinoderms
Brittle Stars
Diversity of Echinoderms
• Sea Urchins
Diversity of Echinoderms
• Sea Cucumbers
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