Biol 11 Lesson 1 Mar 2 - Ch. 27 Mollusca

Homework from last Homework from last class:class:Read Ch. 27-1 MollusksRead over class notes and check out the class

blog: http://msoonscience.blogspot.com/

Phylum Mollusca:Phylum Mollusca:MollusksMollusksChapter 27: Mollusks and Annelidspp. 584-593

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 MollusksIntroduction to MollusksPhylum Mollusca – Latin molluscus = “soft”Bilateral symmetry3 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 MollusksIntroduction to MollusksMollusks 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.

586

Classes of MollusksClasses of Mollusks1) 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 MollusksClasses of Mollusks3) 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 MollusksMollusksMollusks 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 MollusksMollusksRespiratory 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

Ecology of MollusksEcology of MollusksBivalves used to check pollution levels –

“environmental monitors”Range of lifestyles: predators, scavengers, filter

feeders, etc.Crop damage – slugs, snails on landShip damage – shipworms in waterFood source for humans: clams, oysters,

mussels, etc.• Humans can get poisoned by eating mollusks contaminated with toxic protists cause “red tide”

Video – “Mollusks”

Homework for next class:Homework for next class:Complete Ch. 27 Phylum Mollusca worksheetColour Mollusca (clam) diagram – include a

legende.g. Excretory

CirculatoryStudy for Mollusca quiz!Read over class notes and check out the class

blog: http://msoonscience.blogspot.com/

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.htmhttp://www.sciencewithme.com/learn-about-mollusks/http://www.bio.miami.edu/dana/106/106F06_12.htmlhttp://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