Transcript The Animal Kingdom Chapter 2: Mollusks, Arthropods and

The Animal Kingdom
Chapter 2: Mollusks, Arthropods and
Echinoderms
Phylum Mollusca: Snails, Clams, Squid
• Characteristics:
–All have soft bodies and
bilateral symmetry.
–The Latin word, “mollis”
means “soft”.
–Most secret hard,
calcium carbonate
shells to protect
themselves.
• Although they don’t look much alike at
first, a snail, a clam, and a squid have
the same basic body structures.
• Basic body pattern of most
mollusks:
1. Head: containing the mouth
2. Muscular foot: for crawling,
digging, or swimming.
3. Mantle: a thin layer of tissue that
surrounds the main body organs.
The mantle secretes the shell.
4. Gills: used to breath oxygen from
water.
• Classes of mollusks include:
1. Gastropoda (stomach-foot) —
snails, slugs, and sea slugs.
*One shell (univalve)
*Live in the water or on land
*Make beautiful sea shells
*Use a flexible ribbon of
tiny teeth called a
radula to get food.
*Some are herbivores
*Some are carnivores
Attack of the Cone Snail 2:41
Snail Zombies 1:53
Mouth
Radula
Radula Teeth
2. Bivalvia (two-shells)-- clams, oysters,
scallops and mussels.
*Filter feeders—most are omnivores
*Economically important as food
*Used in production of pearls.
- Mollusks
•A razor clam digs into the mud by changing
the shape of its foot.
Giant Clam Video 1:45
3. Cephalopoda (head-foot) —
octopus, squid, cuttlefish, and
chambered nautilus.
*Muscular foot is divided into
tentacles for swimming.
*Complex and intelligent.
*Range in size from 1-60 feet.
*Carnivores
*Crawl or swim by jet propulsion
*Not all cephalopods have a shell
Octopus—no shell
Squid—internal shell
Octopus regeneration 2:03
Octopus flexibility
Chambered Nautilus
external shell
Squid video 3:38
Phylum Arthropoda:
Jointed Legs
• Characteristics:
–Largest group of animals with over
1 million species known. That
number may be as high as 10 million.
–Exoskeleton made of chitin. Must
be shed from time to time in a
process called molting.
–Segmented bodies
–All have jointed appendages (legs,
antenna, pinchers and claws)
–Open circulatory system
–Bilateral symmetry
–One-way digestive tract
• Five classes: Arachnida, Crustacea,
Chilopoda, Diplopoda, Insecta
1. Crustaceans: crabs,
lobsters, crayfish, shrimp
and pill bugs.
*Most have two body regions:
cephalothorax and
abdomen.
*Five pairs of appendages
including large pinchers on
most.
*Most have two pair of
antenna
Fiddler crab
Pill Bug
Crayfish
2. Arachnids: spiders, scorpions,
mites and ticks.
*Most have two body regions:
abdomen cephalothorax.
*simple eyes
*poison glands,
fangs or stingers
*four pair of legs
–Spiders are found
everywhere. They
spin webs using
spinnerets in their
abdomen.
–Scorpions are found in
tropical areas and hunt insects
and spiders.
–Ticks are external
parasites that feed on
the blood of a host.
Some transmit Lyme
Disease and Rocky
Mountain Spotted
Fever.
–Mites are usually
found in dust and are
mostly harmless.
3. Chilopoda: centipedes
*Long, flat bodies with one pair of
legs per body segment.
*Carnivores: eat snails, slugs and
worms and can bite humans.
4. Diplopoda: millipedes
–Long, rounded bodies with two pairs
of legs per body segment.
–Plant eaters: will not bite humans
5. Insects: largest group of arthropods
– Three body segments: head, thorax and
abdomen.
– Three pairs of legs attached to the thorax.
– One pair of antenna.
– Some have one or two pairs of wings; some
have no wings.
– Large, compound eyes; some also have
simple eyes.
– Open circulatory system.
Wings
Abdomen
Antenna
Thorax
Head
Compound
Eyes
3 Pair of Legs
–All insects undergo metamorphosis
*This is a process in which an
animal’s body undergoes dramatic
changes in its life cycle.
*Two types of metamorphosis:
Complete and Gradual
-Stages of Complete Metamorphosis:
*Egg, Larva, Pupa, Adult
(Beetles, bees, butterflies, flies and
ants use complete metamorphosis)
- Insects
Life Cycle
• An insect with complete metamorphosis
has four different stages: egg, larva, pupa,
and adult.
–Stages of Gradual Metamorphosis:
*Egg, Nymph, Adult
(Grasshoppers, termites, cockroaches
and dragonflies use gradual
metamorphosis)
- Insects
• An insect with gradual metamorphosis has
no distinct larval stage. An egg hatches
into a stage called a nymph, which usually
looks like the adult insect without wings.
Phylum Echinodermata:
Seastars
• 6,000 species of spinyskinned animals
• All have radial symmetry.
• “Echinoderm” means
“spiny-skin”.
• Have an internal skeleton
made of spines that extend
out through the body.
• All live in the ocean.
• Move using a water-vascular system
and tube feet.
• Most can regenerate lost body parts
and can occasionally reproduce this
way.
Characteristics of Echinoderms
•Echinoderms, such as this sea star, have a
water vascular system that helps them move
and catch food.
Tube
Feet
Stomach
Madreporite
Water Vascular
System
• Examples of echinoderms:
1. Sea stars and brittle stars: have
5 or more arms lined with tube feet.
Feed on clams by inserting their
stomach into the clam and digesting
it inside the shell.
2. Sea urchins and sand dollars: do
not have arms. Covered with
movable spines used for defense
and movement.
3. Sea cucumbers: leathery skin
with no spines. Spits out its
internal organs to confuse
predators.