Today

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Today

• Practical
• Movie
• Lecture on Molluscs and Arthropods
• Do Labs 5, 6, 7
• Next week quiz, Lab Reports are due

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(No Transcript)
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Phylum Mollusca
Class Polyplacophora-Chitons
Class Bivalvia Clams, Mussels, Scallops, Oysters
http//www.miljolare.no/data/ut/art/?or_id2805
Class Gastropoda Snails and Slugs
A giant squid! -rarely seen alive
Class Cephalopoda- squid, octopus, cuttlefish,
nautilus
http//bioweb.uwlax.edu/zoolab/
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Phylum Mollusca
Habitat marine, freshwater, terrestrial Symmetry
Bilateral Development Protostome Body
Cavity/Germ Layers coelomate (but often coelom
very reduced). Triploblastic Skeleton
soft-bodied animals, but most have a hard shell
secreted by the mantle
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Phylum Mollusca
Movement Chitons, snails, and slugs use
foot clams - sessile, use foot only to
burrow Cephalopods propel water out of siphon,
foot developed into a ring of arms and tentacles
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Phylum Mollusca
Digestive System complete with mouth, gut, and
anusGastropods scrape food, Bivalves filter
feed, Cephalopods are predators Excretory one
or two kidneys Circulatory usually open system
with a heart, short arteries, and freely
circulating hemolymph however Cephalopods have a
closed circulatory system Gas Exchange
diffusion through body surfaces, gills, lungs,
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Phylum Mollusca
Nervous paired ganglia, nerves, giant axons in
squid, acute eyesight in octopuses
Reproduction sexual reproduction, sexes
usually separate Distinguishing Characteristics
all have a muscular foot, a mantle, and a
visceral mass
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Phylum Mollusca
Know 4 major classes in this phylum
1. Class Polyplacophora many plates 8 plates
together make shell flat muscular foot for
crawling have radula for scraping algae off
rocks chitons (look at preserved specimens, ID
major parts) 2. Class Gastropoda single shell
produced by mantle (or no shell at all) foot and
radula similar to Polyplacophora distinct head
(part of foot!) snails, slugs (look at
preserved specimens, live snails, snail slime
demo)
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Phylum Mollusca
3. Class Bivalvia look at preserved specimens
of clams, mussels, scallops, oysters, dissect a
clam
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4. Phylum Mollusca Class Cephalopoda
look at preserved specimens, dissect a squid
Know fins, mantle, arms, tentacles, and siphon.
Note that there is no external shell. To see the
shell you have to pull out all of the guts and
look under them (do this AFTER you explain the
other parts to your lab partners!). Which are
longer, the tentacles or the arms?
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Squid Dissection
shell
Calamari rings are the mantle!
Know mantle, gills, branchial hearts, systemic
heart, ink sac, esophagus, stomach, anus. Look
for the penis and testes, but you might have a
girl squid (youll see an ovary filled with
eggs).
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Squid Dissection head-foot region
shell
Know the arms, suckers, and the horny beak. What
is the horny beak used for? (Feel it it is
quite sharp!)
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Phylum Arthropoda
Subphylum Trilobita
Subphylum Uniramia
Class Diplopoda
Class Insecta
Class Chilopoda
Subphylum Chelicerata
Subphylum Crustacea
Class Merostomata
Class Arachnida
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Phylum Arthropoda
Habitat marine, freshwater, terrestrial Symmetry
Bilateral Body Cavity/Germ Layers coelomate
(hemocoel), triploblasticDevelopment
Protostome Skeletal support exoskeleton with
chitin, secreted by the epidermis periodic
molting with growth Movement true limbs like
legs and wings
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Phylum Arthropoda
Digestive System complete, complex,
compartmentalized Circulatory open circulatory
system heart with short arteries hemolymph
hemocoel Gas Exchange diffusion through body
surfaces gills, spiracles and trachea (air
tubes), or book lungs
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Phylum Arthropoda
Nervous pair of ventral nerve cords with several
segmented ganglia and a dorsally located
brain Reproduction usually sexual, internal,
with the sexes separate Another distinguishing
characteristic segmented body (joint foot)
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Phylum Arthropoda
4 major SUBPHYLA 1. SP Trilobita antennae
lots of legs flattened 3-lobed trilobites
extinct! (look at fossils) 2. SP Crustacea
crusty (vs hard shell) 2 pairs antennae many
appendages several classes - lobsters,
crayfish, crabs, shrimp, barnacles, pillbugs,
Daphnia (look at preserved and live specimens,
crayfish dissection)
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Phylum Arthropoda
3. SP Uniramia named for uniramous appendages
(vs biramous for Crustacea) one pair antennae
Class Insecta insects Class Chilopoda
centipedes Class Diplopoda millipedes (look
at preserved specimens, esp. grasshopper for
external anatomy) 4. SP Chelicerata no
antennae head/thorax fused (cephalothorax) have
chelicerae book lungs in some Class
Merostomata horseshoe crabs Class Arachnida
spiders and mites, scorpions (look at horseshoe
crabs, preserved and live scorpions and spiders)
Tank is the live scorpion.
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Class Insecta (Phylum Arthropoda, Subphylum
Uniramia)

• largest group of arthropods, by far!
• head, thorax, and abdomen
• one pair antennae
• three pairs of legs one on each segment of
  thorax
• one or two pairs of wings in adult
• spiracles and tracheae for respiration
• complete OR incomplete metamorphosis

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Complete metamorphosis egg larva
pupa adult
Larvae are maggoty
Pupation of monarch butterfly
Adult insect
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Incomplete metamorphosis egg nymph
adult
Nymphs look more like adult they gradually
develop, rather than pupating.
dragonflies
stoneflies
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Some insects from alpine streams in Colorado
larvae
nymphs
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Crayfish
(chelipeds are typically considered walking
legs)
Refer to Figures on p. 6746 for external and
internal crayfish anatomy.
Is the pointer on a telson or uropod?
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Crayfish Dissection
hard to find!!
Start with anterior by cutting open carapace
later, cut all the way down abdomen to see
muscles and extension of intestine.
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Crayfish Dissection Internal
Work in groups of 2 or 3 (2 crayfish per table,
get one of each sex. Look at swimmerets to tell
male has first pair modified for sperm transfer
female uses them to hold eggs)
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Crayfish DissectionThis is a ventral view to
find ventral verve cord, rip out abdominal
muscles!
If you suck the heads of crayfish, part of what
you get is the green glands, which are analogous
to bladders for waste excretion!
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Name three things that allmollusks have?
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How do _________ get their food? Bivalves? Squi
ds and Octopuses? Snails and Slugs?
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What does the mantle secrete?
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To what class does this organism belong?
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To what class does this organism belong?
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• How many legs does a spider have?
• How many legs does an insect have?

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• How many legs are on each segment of a
  millipede?
• How many are on each segment of a centipede?

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What part of the insect is the arrow pointing to?
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Is the circulatory system of the organism open or
closed?