Phylums of Worms and Phylum Mollusca
WORM PHLYA
• Worms are general grouping
• Worms have bilateral symmetry
– Allows for more sophisticated behaviour
• Worms are the beginning of advanced
inverts
– Evolved organs and other specialization
– Evolved complete digestive tracts
– Body cavity/ coelem
• found in most bilateral animals
• organs are suspended in this space
Worm Phylas
• Worms are soft bodied so they
mostly live in tubes, burrows or
under something
• Feeding ranges from parasites to
carnivorous hunters
• Some worms create mucous nets
to catch food while they are safe in
their burrow
Platyhelminthes - Flatworms
• Advancements include…
– Central nervous system (brain)
– Muscles
– Simplest of animals with bilateral
symmetry
• Three classes of flatworms
– Turbellaria: carnivorous hunters
– Trematodes and Cestodes which are both
parasitic
Tapeworm found on Tiger sharks and mackerel.
http://www.marineparasitology.com/Papers/Palm%20&%20Klimpel%202007.pdf
biology.unm.edu/.../Summaries/SimpleAnimals.htm
Nemertea- Ribbon worms
• Advancements…
–Nervous system with a brain
–Muscles
–Circulatory System with blood
vessels
–Complete digestive tract (mouth
and anus)
Ribbon worms continued-
• Stretchy bodies (8 in can
stretch to 3 ft)
• Gather food with a proboscis
that everts from inside them to
catch food
• Proboscis may be sticky or
poisoned
www.seamuse.com/rhyncocoela.htm
www8.nos.noaa.gov
Nematode - Roundworms
-Body cavity
-Have to molt cuticle as they grow
-Live in sediments and tissues of orgs
-parasitic & predatory
Annelida – Segmented Worms
– Head-like area with a brain
– Segmentation- repeated compartments
• Helps with motion
• Allows for appendages
http://faculty.clintoncc.suny.edu/faculty/Mic
hael.Gregory/files/Bio%20102/Bio%20102
%20Laboratory/Animal%20Diversity/Lopho
trochozoans/img012.jpg
Class Polychaeta
• Each segment has a flattened extension
called parapodia
• Gills for breathing
Class Oligochaete
• burrow in mud and sand
• Scavengers
Class Hirudinea
• Live on whatever they are “eating”
• Parastic / blood sucking
• Sucker at each end
http://scienceblogs.com/photosynthesis/Hermodice-carunculata59(c)BNSullivan.jpg
ua.intervet.com/news/2007-11-25.aspx
www.inhs.uiuc.edu/.../AOGSMNP.OligoIntro.html
Sipuncula – Peanut Worms
• Recent studies have placed them
with Annelids even though they
aren’t segmented
• Bottom dwellers, many burrow
• Deposit feeders
www.wildsingapore.com/.../sipuncula.htm
www.ucmp.berkeley.edu/sipuncula/sipuncula.html
Echiuria- Sausage Worms
Like the Peanut Worms
Pogonophora –Beard Worms
• Lack a digestive system
• Symbiotic bacteria at
hydrothermal vents provide them
food
Vent community worms, live in tubes
Use bacteria in them to manufacture food
Tube worms
White Tube worm
www.nematodes.org/.../odl_pogonophora.html
Chaetognatha- Arrow Worms
• All the features of a complex
org
• Eyes and a distinct head
• planktonic
• vicious carnivores preying on
larvae of other animals
Lophophorates…colonial worms
• All the features of complex orgs
• Lophophore- unique feeding structure
with ciliated tentacles
–Suspension feeders
• Two groups-Bryozoans and
Phoronids
Phylum Mollusca
• Evolutionary advances in specializing
parts of the body
• Advancement in the nervous system
– Squid and octopus are as intelligent as some
vertebrates
– Allows for more sophisticated behaviors
• Very successful phylum and one of the
most diverse
Phylum Mollusca
• Wide diversity
of form but
based on
general body
plan
http://palaeo.gly.bris.ac.uk/Palaeofiles/Fossilgroups/Cephalopoda/BAUPLAN.JPG
http://www.manandmollusc.net/
Mollusc Body Plan
All molluscs have or had: Foot, Mantle,
Shell and Radula
Mantle – tissue which secretes shell
Bilateral symmetry
Body Cavity
Open circulatory system with
compartmentalized heart (except
cephalapods)
Phylum Mollusca
Class Polyplacophora….
chitons
http://www.geocities.com/Yosemite/Gorge/5604/chitonsrickettslarge.jpg
Phylum Mollusca
Class Bivalvia “two shells”
Ex. Clams, mussels,
scallops
http://www.xconomy.com/wordpress/wp-content/images/2008/12/scallop_eyes.jpg
http://www.sciencedaily.com/images/2006/10/061006072601.jpg
•
cses.washington.edu/.../ae/aekeyfindings.shtml
Figure 2 Geoduck
Clams. Geoducks are a
species of long-lived
(100+ years) saltwater
clams (Panope
generosa) native to the
northern Pacific coasts
of Canada and the U.S.
Pacific Northwest.
Washington State’s
Puget Sound bays and
estuaries harbor the
highest density of
geoducks in the
continuous United
States (Washington
Dept. of Ecology).
Photo courtesy of Are
Strom. Used with
permission.
Phylum Mollusca
Class Scaphapoda…tusk shells
: www.dkimages.com/.../GreenTusk-Shell-1.html
Phylum Mollusca
Class Gastropoda “stomach foot”:
snails, slugs and limpets
http://www.ucmp.berkeley.edu/images/taxa/inverts/shell_morph.jpg
Phylum Mollusca
Class Cephalopoda…
squid, octopus
http://pics.livejournal.com/krakenwakes/pic/00003p9r
Shells of Shellfish
• Three layers: conchin, CaCO3
in conchin matrix, and
nacreous made of CaCO3 with
some conchin in sheet-like
pattern (mother-of-pearl).
• Wide variety of shapes.
• Reduced shells (sea hares,
squid pen, cuttle bone).
• Lost shells (octopus,
nudibranchs)
http://upload.wikimedia.org/wikipedia/commons/thumb/5/50/Valve-InternalView.png/300px-Valve-InternalView.png
Mollusc Locomotion
• Have a muscular foot for crawling,
swimming, burrowing
• Modified into tentacles for squid & octopus
– Muscles forces water out siphon or funnel for
swimming.
• Byssal threads- protein strands used to
anchor some shellfish to a surface
http://www.huntsmanmarine.ca/assets/images/slide18.gif
Sense Organs
Well developed nervous system in cephalopods
Chemosensory organs- sense chemicals by smell
or taste
Cephalopods have highly developed eyes.
Distinct images and possibly color (1 species of
squid).
•
http://images.google.com/imgres?imgurl=http://www.phy.duke.edu/~hsg/54/table-images/scallop-witheyes.jpg&imgrefurl=http://www.phy.duke.edu/~hsg/54/&usg=__lOBprQin3JucMYHMZe9hGogM0e0=&h=510&w=793&sz=60&hl=en&start=5&
tbnid=j5c6lTW_u_E6TM:&tbnh=92&tbnw=143&prev=/images%3Fq%3Dscallop%2Beye%26gbv%3D2%26hl%3Den%26sa%3DG
Interesting Characteristics
Color change in cephalopods using
chromatophores.
Cells that contain pigments and are
under nervous system and hormonal control.
http://imagecache01a.allposters.com/images/pic/NGSPOD/124954-FB~Close-View-of-the-Chromatophore-Laden-Skin-of-a-Squid-Posters.jpg
http://upload.wikimedia.org/wikipedia/commons/3/3d/Striped_pyjama_squid.jpg
Mollusc Feeding
Radula
Used for scraping, boring,
and sometime associated
with toxins.
www.jaxshells.org/rad.htm
Cephalapods
Cephalopods highly
mobile predators.
Catch prey with suckered
arms.
Neurotoxins associated
with beak in octopus.
http://precordialthump.medbrains.net/files/2009/01/octopus-beak.jpg
Bivalves
• Filter feeding
• Water comes through a siphon,
passes over ctenidia, exits over
anus and out exhalent siphon
• Siphons are a flexible tube.
• Food particles sorted by
ctenidia
http://static.howstuffworks.com/gif/willow/geoduck-info0.gif
Gastropods
• Gastropod feeding habits are
extremely varied, although most
species make use of a radula in
some aspect of their feeding
behavior.
• Some graze, some browse, some
feed on plankton, some are
scavengers or detritivores, some
are active carnivores.
Mollusc Digestion
• Complete digestive
system
• Stomach often has
a crystalline stylerod with enzymes
•Food then goes to a
digestive gland and to
its intestine. Waste
passed through anus.
How do molluscs reproduce and develop?
http://www.marlin.ac.uk/php/image_viewer.php?images=crefor&topic=Species
Mollusc Reproduction and Development
Separate sexes and sexual reproduction
Some lay eggs and some bear live young
Some with internal and external reproduction
http://homepage.uab.edu/acnnnghm/BY255L/BY255LImages/BY255LImages-Mollusca/WhelkEggCase-2.jpg
http://1.bp.blogspot.com/_pbKM4qxmq4c/SItJHG3rmHI/AAAAAAAAEms/D2Fh4ujwQ6I/s400/03.jpg
Circulatory System
exception
• Cephalopods have
closed circulatory
system.
• More efficient
circulation which
allows them to be
fast hunters.
news.nationalgeographic.com/news/2006/12/0612...
Human and Mollusc Interaction
• Source of food
• Shells are a source of calcium for some
birds
• Crushed shells are used to kill
agricultural pests. Mollusks also nourish
humans culturally.
• Mollusk shells served as money in some
early cultures
• Species health is used in monitoring
water pollution
True or False
• All cone shells possess a poisonous dart
(their"radula"), with which they harpoon,
inject venom and kill their prey. Cone shell
venom is toxic enough to hurt or even kill a
full-grown man!
http://publications.nigms.nih.gov/findings/sept02/images/shells.jpg
True or False
• Most shelled molluscs can make pearls
• They coat the foreign substance with nacre, the same as the lining of
their shell.
• Stimulus include organic material, parasites, or even damage
• Pearl oysters take up to 7 years to grow pearls big enough for jewelry.
iSyBlALg/SbgT6kWBw4I/AAAAAAAAAOc/-8OW3-ypwc4/s400/Natural%2BPearls%2BCollage.jpg&imgrefurl=http://www.pearl-professor.com/&usg=__RUA4pRNos1yOfGwtkHVWmYmT9d8=&h=400&w=3
True or False
• The largest known bivalve
was a "Giant Clam"
(Tridacna gigas which weighed
in at an amazing 734 pounds
(333kg!!) and was nearly four
feet (1.4m!!) in length.
• It can swallow a diver
http://www.waterworxbali.com/Images/Photos/Large/giant-clam-diver.jpg
True or False
• The blue-ringed octopus is currently one of the
most toxic known sea creatures, next to the
box jelly
http://aycu28.webshots.com/image/42027/2005963218169739155_rs.jpg