phylum mollusca
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Phylum Mollusca. Chapter 13: Phylum Mollusca pp. 329-334. Biology fun facts of the day:. Experts claim that about 1,000 oysters must be opened in order to find one usable pearl!. Biology fun facts of the day:. - PowerPoint PPT PresentationTRANSCRIPT
Biology fun facts of the day:
Experts claim that
about 1,000
oysters must be
opened in order to
find one usable
pearl!
Biology fun facts of the day:
The common garden snail,
Helix aspersa, can travel about
2 feet in 3 minutes. At that
rate, it would travel 1 mile in
5.5 days.
(Now you know where the
term ‘snail mail’ comes from!)
Biology fun facts of the day:
When we hold a large seashell up
to our ear, you can hear what
sounds like waves because the
shell echoes all the sounds
around you.
If you could listen to a shell in a
completely soundproof room, you
would hear nothing at all!
Biology fun facts of the day:
Many land snails can lift 10 times
their own weight up a vertical
surface. (If you were this strong,
and you weighed 30 kg (about 70
lb), you could carry 300 kg
(almost 700 pounds!!!) straight
up a wall!
Introduction to MolluscsIntroduction to MolluscsMolluscs represent the second largest animal phylum, following the arthropods
= Old Phylum (500 million years, approx.)
80,000 – 100,000 existing species (estimate)
Most species are free-living
Inhabit a variety of marine, aquatic & terrestrial habitats
Important ecological roles with regards to nutrient recycling; bivalves clean and recycle sediments
Empty shells provide habitat for other invertebrates
Introduction to MolluscsIntroduction to MolluscsPhylum Mollusca – Latin molluscus = “soft”ProtostomesBilateral symmetry; eucoelomates3 cell layers (ectoderm, endoderm,
mesoderm)Have a coelom (but often reduced to a
cavity that surrounds only the heart)Have trochophore larvae (free-swimming
ciliated larva)
• Similar larvae in annelids
likely share a common ancestor
Introduction to MolluscsIntroduction to MolluscsMolluscs all share similar developmental patterns and a common body plan:Foot (muscle; function varies)Shell (protection; made of CaCO3)Mantle (produces the shell)Visceral mass (contains internal organs)
Diagrams of snail, clam, and squid p.
300
Classes of MolluscsClasses of Molluscs
1) Class Bivalvia• 2 hinged shells• No head or eyes• Gills; live in water
Example members: clams, oysters, scallops
2) Class Gastropoda• One shell• Some are terrestrial
Example members: snails, slugs, nudibranchs
Classes of MolluscsClasses of Molluscs3) Class Cephalopoda Fast-moving predators Foot is modified into tentacles Well-developed nervous system Some can use camouflage and jet
propulsion (e.g. octopus) when they feel threatenedExample members: octopus, squid, nautilus, cuttlefish
Octopus
Nautilus
Squid
Form and Function of Form and Function of MolluscsMolluscsMolluscs vary a lot clam = representative molluskDigestive system: •Complete digestive tract (mouth anus)
• Mouth, esophagus, stomach, intestine, anus•Have a radula (scraping/drilling organ) or a beak (cephalopods)•Bivalves trap food in their gills – no radula
e.g. Gastropod
Form and Function of Form and Function of MolluscsMolluscsRespiratory system: • Aquatic mollusks have gills• Terrestrial mollusks have a highly folded
mantle for O2/CO2 exchange (must stay moist)
*A clam has incurrent and excurrent siphons sea water passes through; location of gas exchange
Circulatory system:• Open circulatory system – the heart
pumps blood through open spaces called sinuses instead of through blood vessels
Excretory system: • Nephridia (primitive kidneys) remove
metabolic waste (nitrogen-containing wastes like NH3)
• Digestive wastes go out anus
Nervous system:• Bivalves – reduced nervous system; no
head• Gastropods – fairly basic• Cephalopods – very well developed
• Good vision, small ganglia near mouth, statocysts (balance), simple chemical and touch receptors
• Good dexterity and memory – they can learn!
Musculoskeletal system:• Muscular foot for movement• Bivalves – “two shell”; foot pulls animal
forward, and can be sucked back in (for protection)
• Gastropods – “stomach foot”; they slide forward on broad ventral foot (use muscus)
• Cephalopods – “head foot”; foot has been modified into many tentacles with suction cups
e.g. Gastropod
Reproduction:•Some Monoecious (have both sex organs, capable of producing both sperm and eggs)•Others are Dioecious (either male or female gonads, can produce one type of gamete only)
•Separate sexes (usually)
•External fertilization (broadcast method) in bivalves/marine gastropods) the female traps sperm
•Internal fertilization in cephalopods/terrestrial gastropods
Ecology of MolluscsEcology of MolluscsBivalves used to check pollution levels –
“environmental monitors”
Range of lifestyles: predators, scavengers, filter feeders, etc.
Crop damage – slugs, snails on land
Ship damage – shipworms in water
Food source for humans: clams, oysters, mussels, etc.
• Humans can get poisoned by eating mollusks contaminated with toxic protists cause “red tide”
Mollusc (5-7-5) Haiku:Mollusc (5-7-5) Haiku:
Slow, slick, sliding slug
Terrestrial explorer
No protective shield
Create your own mollusc haiku in 5-7-5 format!
Works CitedWorks CitedImages taken from the following
sources:http://other95.blogspot.com/2007/10/circus-of-
spineless-26-like-being-home.htmlhttp://offthemark.com/search-results/key/mollusk/http://kevinmainjewelry.blogspot.com/2010/06/pearl-fun-facts-and-care-tips.htmlhttp://seashellvilla.com/advertise_here.htmlhttp://www.zazzle.com/snail_mail_postcard-239469706654312651http://bio1151b.nicerweb.com/Locked/media/ch32/trochophore.htmlhttp://www.education.com/study-help/article/biology-help-mollusks-clam-up-would-ya/
Works CitedWorks Citedhttp://www.thecanadianencyclopedia.com/index.cfm?PgNm=TCESearchMedia&Params=A1&MediaId=385http://perfectgardeningtips.com/category/plants/pest-control/http://www.apartmenttherapy.com/sf/insects-pests/slugs-082896http://birdhouse.org/blog/2008/05/16/nudibranchs/http://www.zazzle.com/i_squid_cephalopods_tshirt-235319078835508111https://www.mentalfloss.com/blogs/archives/58856http://radio-weblogs.com/0105910/2004/01/10.htmlhttp://ihatetheocean.blogspot.com/2010/08/august-6-2010-nautilus.htmlhttp://zollberg.co.cc/bivalve.html
Works CitedWorks Citedhttp://js082.k12.sd.us/My_Classes/Advanced_Biology/
Ch_25/Clam%20Dissection/Clam_Dissection.htm
http://www.sciencewithme.com/learn-about-mollusks/
http://www.bio.miami.edu/dana/106/106F06_12.html
http://nashzoology.ning.com/forum/topics/mollusk-classification-choose?commentId=2223964%3AComment%3A10692&xg_source=activity
http://sharon-taxonomy2009-p3.wikispaces.com/Mollusca
http://www.lifeinfreshwater.org.uk/Web%20pages/ponds/Pollution.htm
http://www.nero.noaa.gov/nero/hotnews/redtide/
http://www.sheppardsoftware.com/content/animals/profile_mollusks.htm