Transcript Notes Moll, Arth, Echinoderms

Phylum Mollusca
• Means “soft”…refers to their bodies
• Are coelemates…three body layers
with true body cavity
• Two body parts:
– Head-foot…travels on and has sensory
organs
– Visceral mass…organs
• Body covered by mantle (and often a
shell)
• Bilateral symmetry
Phylum Mollusca
• Systems:
– Complete digestive system
– Separate sexes, external fertilization
(some hermaphrodites)
– Breathe through gills
– Open circulation (hemolymph)
Phylum Mollusca
Phylum Mollusca
• Radula: “tongue”
structure
covered with
“teeth” (made
of chitin)
scrape food.
Phylum Mollusca
• 3 Classes
–Gastropoda
–Bivalvia
–Cephalopoda
Class Gastropoda
• “stomach-foot”… crawls on
“stomach”
• Snails, slugs, conch
• Visceral mass turns 180o so
organs exit out front (torsion)
• All are motile
Class Gastropoda
Nudibrach
Class Bivalvia
• 2 halves (valves) to the shell
• Clams, mussels, oysters, scallops
• Most are sessile and filter feed
• No head or brain, 3 pairs of
ganglia
• Separate sexes, external
fertilization (most)
Class Bivalvia
Class Cephalopoda
• “head foot” travel around head
first, tentacles
• Octopi, squid, cuttlefish, nautilus
• Most advanced nervous system of any
mollusk…lobes, complex eyes
• Closed circulatory system (more
advanced…move faster)
• Separate sexes, internal fertilization
• Chromatophores (change color), ink
http://www.youtube.com/watch?v=zjycOCyUZ1c
Phylum Echinodermata
• “spiny skin”
• Sea stars, sand dollars, sea urchins,
sea cucumbers
• Radial symmetry (bilateral larva)
• No cephalization
• Ossicles (endoskelton)
• Water-vascular system (not blood or
hemolymph)
• Tube feet (water filled … suction)
Tube feet
Class Crinoidea
e.g. crinoids, sea lillies, feather stars
Class Ophiuroidea
e.g. brittle stars and basket stars
Class Echinoidea
e.g. sea urchins, sand dollars
Class Holothuroidea
e.g. sea cucumber
Class Asteroidea
•
•
•
•
“star like”
Sea stars (star fish)
Oral/aboral side (mouth/not mouth)
Uses water in tubes through body for
circulation (water-vascular system)
• 2 stomachs…one goes out of body
• Nerve ring, radial nerve down each
arm, eye spot (light)
• Separate sexes, external fertilization
Phylum Arthropoda
• “jointed foot”
• Segmented animals with appendages
(“arms/legs”)
• Exoskeleton for protection and
support
• Molt when they grow (shed exo.)
• Highly cephalized…compound eye,
antennae, brain
• Open circulatory system (hemolymph)
Subphylum Crustacea
• Very diverse … only 1 characteristic in
common … 2 pairs of antennae
• Most:
–
–
–
–
Mandible (jaws)
1 pair of appendages per segment
Segments fused together
Some breathe with gills, some through
holes in exoskeleton
– Indirect development (larval stage
naupilus)
Crayfish
• Decapod … “10 feet”
• 2 body parts:
– Cephalothorax (head, 5 segments,
thorax)
– Abdomen
• Antennae (long … touch, taste)
• Antennules (short … touch, taste,
balance)
Crayfish
• Mandibles to chew
– Maxillae and maxillipeds to manipulate
food
•
•
•
•
•
•
Walking legs, pinchers, swimmerets
Complete digestive system
Gills (legs make currents)
Open circulatory system
Green gland for waste
Brain
Subphylum Crustacea
Subphylum Chelicerata
and Myriapoda
• Chelicerata includes spiders,
scorpions, mites, horseshoe
crabs, ticks
– Have special mandibles called
chelicera
– Special lungs called book lungs
• Myriapod (“many feet”)
– Millipedes and centipedes
Subphylum
Chelicerata
Subphylum
Myriapoda
Class Insecta
• Insects…technically only 1 order
(Hemiptera) are bugs
• Segmented bodies (3 parts)
– Head, thorax, abdomen
• Exoskeleton (breathe through
holes in exoskeleton)
• Jointed legs (3 parts)
Order Hemiptera
• Bugs
• Damage crops, spread
disease 
Order Hemoptera
• Aphids, cicadas
• Damage crops,
young trees 
Order Isoptera
• Termites
• Damage wood in
buildings 
• Recycle wood in
forests 
Order Odonata
• Dragonflies,
damselflies
• Destroy
harmful
insects 
• Nymphs are
food 
Order Orthoptera
• Grasshoppers,
crickets, preying
mantis
• Damage crops 
• Eats pests 
Order Coleoptera
• Weevils, beetles,
ladybugs
• Damage crops,
trees 
• Eat other
insects 
Order Diptera
• Mosquitoes, flies,
gnats
• Carry disease,
destroy crops 
• Pollinate flowers,
decompose 
Order
Hymenoptera
• Bees, wasps,
ants
• Pollinate flowers,
honey, destroy
pests 
• Sting 
Order Lepidoptera
• Butterflies,
moths
• Pollinate
flowers, make
silk 
• Larva damage
crops 
Incomplete
metamorphosis
• Direct development
• Young look like
adult, except
smaller and often
without wings
• Young are called
nymphs.
• Often several molts
(shed exoskeleton)
to become adult
Complete Metamorphosis
• Indirect
development
• Young do not
look like adult
• Often involves a
cocoon
(chrysalis) and
inside is a larva
called a pupa.