Marine Science
Unit 3.9 Mollusks Entry Task(s) What do you know about the following organisms? Mollusks Unit 3.9 Mollusks Vocabulary.
• Using Chapter 9 (pgs. 218-234) of the textbook provide a definition for each term.
• Be sure to complete the vocabulary as we progress through the unit, it will be checked prior to the assessment.
Note: The “Unit 3.9 Mollusks Vocabulary” worksheet can be located on the Marine Science webpage @ link: https://www.steilacoom.k12.wa.us/Page/6827 Entry Task(s) Why is one group of mollusks called bivalves?
• They have two shells that are hinged together.
What kind of symmetry do mollusks have? What does this kind of symmetry mean?
• Bilateral Symmetry • When viewed down the center the left & right sides of the organism will be nearly identical. Graphic Organizer Bivalves & Gastropods GO
Instructions:
• Read through the introduction to the graphic organizer.
• Using pgs. 219-223 of the textbook, fill in the Bivalve half of the graphic organizer.
• Be detailed in your information.
Note: The “Bivalves & Gastropods GO” graphic organizer can be located on the Marine Science webpage @ link: https://www.steilacoom.k12.wa.us/Page/6828 Entry Task(s) What are some of the basic structures of mollusks?
• Soft. • Bilateral symmetry. • Bodies contain head, foot, & coiled visceral mass. • Most have either an external or internal shell.
What allows a bivalve to control the opening & closing of its shell?
• Adductor Muscle Mollusks Mollusks
Animals that inhabit shells
• Protection for their soft bodies.
• Not all mollusks have shells
- Squid & octopus have soft bodies, as well as structural & developmental characteristics of shelled mollusks.
Pg. 219 Mollusks Mollusks
Phylum Mollusca
• 100,000 species classified into several distinct classes.
• Soft, bilaterally symmetrical bodies composed of a head, foot, & coiled visceral mass (internal organs).
• Most have either external or internal shell.
• Advanced features of coelom & brain. Entry Task(s) What can the bands of a clam tell us?
• The age of the clam.
How is the above possible? What does the width of the bands tell us?
• Each band of the clam represent about a years worth of growth.
• Wider bands represent favorable years of growth. Mollusks
What do these organisms have in common?
• Two shells making them bivalves (“two shells”)
Pg. 219 Mollusks Structure of a Typical Bivalve
The two shells are hinged.
• Kept closed by a short, tough adductor muscle.
- Clams, oysters, & mussels have two
- Scallops have one Mollusks Structure of a Typical Bivalve
The clam (Mercenaria) is a common bivalve.
• 15,000 species of clams.
• Live buried in the sand. Mollusks Structure of a Typical Bivalve
The age of a bivalve can often be determined by its shell.
• Each line (or band) is a new layer of shell the clam has • produced in about a year.
• Some bands are wider than others.
- More growth during years with favorable conditions.
• Oldest living clam = 60 years
Pg. 220 Mollusks Structure of a Typical Bivalve
Mollusk shells are made of calcium carbonate (CaCO3)
• A thin membrane (mantle) line the inside & protects internal lineorgans. organs.
- Contains shell glands that secrete calcium carbonate.
Pg. 242 Mollusks Structure of a Typical Bivalve
Pg. 242 Mollusks Life Activities of Bivalves
Bivalves feedconduct & conduct gas exchange gas exchange & feed through a siphon protruding between the shells.
• Incurrent siphon
- water containing food & oxygen enters.
• Excurrent siphon
- Waste products of digestion & respiration are eliminated. Mollusks Structure of a Typical Bivalve
Breathe using gill membranes.
• Surface of gills contain cilia, creating a current.
• Water moves over gill surfaces & dissolved oxygen diffuses through gill membrane.
• Carbon dioxide diffuses back into the water. Mollusks Life Activities of Bivalves
Filter feeders.
• Single bivalve can filter up to five liters of water an hour.
• Plankton & organic debris enters.
• Food particles get stuck in mucus that coats gills & mantle.
• Ciliated cells moves food to the mouth (opposite siphon).
• Food digested in a one-way digestive tract.
• Open circulatory system in which nutrients & oxygen are transported via colorless blood. Mollusks StructureLife Activities of a ofTypical Bivalves Bivalve
Adaptations that secure bivalves to substrates.
• Mussels live in turbulent waters with constant wave action.
- Tough byssal threads made of a fibrous protein.
- Secreted from gland in the foot.
- Firmly attach them to hard substrates.
Pg. 222 Mollusks StructureLife Activities of a ofTypical Bivalves Bivalve
Adaptations that secure bivalves to substrates.
• MusselsOysters havelive in a turbulentflat upper waters shell that fits the curved lower shell.
- Lower shell secretes a cement that adheres to substrates.
- Dental scientists interested in chemical properties for dental fillings.
Pg. 219 Mollusks Life Activities of BivalvesStructure of a Typical Bivalve
Adaptations that secure Adaptationsbivalves to substrates. that secure bivalves to
• Under the proper conditions,• Under oysters the proper & other conditions, bivalves oysterscan produce natural pearls. & other bivalves can produce natural
- Develops when a grain of sand or other particles lodges between the mantle & the shell.
- Mantle tissue reacts by secreting layers of shell around the foreign body, forming a pearl. Mollusks Movement in Bivalve
Not all bivalves adhere to substrates; some bivalves move.
Variety of adaptations for locomotion.
• Scallop is the fastest of the bivalves.
- Quick movements occur when adductor muscle contracts & relaxes repeatedly.
- Water is forced between the shells propelling the scallop. Mollusks Movement in Bivalve
Variety of adaptations for locomotion.
• Other bivalves move rapidly through substrates.
- Razor clam (Ensis directus) & soft-shell clam (Mya arenaria) use their muscular foot for digging.
- Burrowing quickly enables the clam to escape enemies.
Pg. 223 Mollusks Movement in Bivalve
Variety of adaptations for locomotion.
• Some clams, shipworms (Teredo), even burrow through solid substrates, such as wood.
Pg. 223 Entry Task(s) From what are byssal threads secreted?
• Glands in the foot.
From where is the cement of oysters secreted?
• Mantle of the lower shell. Mollusks Reproduction in Bivalve
Separate sexes.
• Fertilization & development are external.
- Eggs & sperm are released into the water where fertilization occurs.
- Early stages of development, bivalves are part of the plankton population.
- When shells form, they sink to the seafloor, settle, & mature into adults. Mollusks Complete the following pertaining to bivalves.
• Read pgs. 218-223 in the textbook.
• Complete the following review within your science notebook:
1) How does a bivalve breathe?
2) Explain how a bivalve feeds.
3) Compare locomotion in the clam & the scallop. Assessment MSS8-3.9 Mollusks Assessment_01
• Grab a copy of the assessment.
• Only using your knowledge of what you have learned complete the assessment.
• Once complete, raise your hand so I can collect your paper. Mollusks How Do Gastropods Carry Out Their Life Functions?
What do these organisms have in common? Mollusks How Do Gastropods Carry Out Their Life Functions?
Gastropods are a diverse group.
• About two thirds of the mollusk population.
• Referred to as univalves (“one shell”)
• In the class of Gastropoda (“stomach-foot”) Mollusks Structures of a Typical Gastropod.
Snails, the most common gastropods, have a single coiled shell.
Pg. 225 Mollusks Structures of a Typical Gastropod.
Glide across substrates on a large muscular foot.
Contain a one-way digestive tract.
• Ingested through the mouth; waste eliminated through the anus.
• Nutrients transported in an open circulatory system.
- One-chambered heart & tiny blood vessels.
- Colorless blood pushed by contractions of the heart & body muscles. Mollusks Structures of a Typical Gastropod.
When not feeding or moving about, a snail retracts its soft body inside its shell.
• Opening covered by operculum, like a trapdoor.
- Composed of a protein.
Pg. 224 Mollusks Life Activities of Snails.
Respiration.
• Takes in oxygenated water through siphon.
• Gills conduct gas exchange.
Movement.
• Carried out by the nervous & muscular system working together.
• Impulses in brain reach foot muscles by motor nerves.
• Have ability to crawl & climb. Mollusks Life Activities of Snails.
Feeding.
• Move along the seafloor grazing on tiny organisms.
• All gastropods have a toothed structure (radula), used to scrape & ingest algae.
• Periwinkle (Littorina)
- Grazes on algae growing on rocks & marsh plants. Mollusks Life Activities of Snails.
Feeding.
• Mud snail (Ilynassa)
- Scavenger feeding on dead, or dying organisms.
- Use radula to tear & shred dead matter into small pieces. Mollusks Life Activities of Snails.
Feeding.
• Moon snail (Neverita)
- Predator that secretes chemicals from gland in foot that softens clam shells.
- Radula drills small hole into hinged area of clamshell.
- Inserts mouth into hole & feeds on the soft-bodied animal inside.
Pg. 226 Mollusks Life Activities of Snails.
Feeding.
• Cone snail (Conus)
- About 500 species
- Predatory snail, that uses toxins to kill prey.
- Harpoon like radula at the end of proboscis used to spear prey.
- Toxin being studied on vertebrate nervous systems as treatment for pain relief.
Pg. 226 Mollusks Reproduction in Snails.
Some species have separate sexes, while others are hermaphrodites.
• Internal fertilization & external development.
• Some deposit fertilized eggs directly into the water, other enclose eggs in protective covering.
• The whelk (Busycon), a predatory snail, produces an egg case composed of several capsule strung together.
- 1-2 dozen per capsule, several hundred in whole egg case. Mollusks Reproduction in Snails.
Some species have separate sexes, while others are hermaphrodites.
• The moon snail eggs develop into larvae within a thin leathery membrane (sand collar).
- Sand collar consists of sand cemented together by mucus.
- 3-5 weeks produce shells & settle on sea bottom.
- Sexual maturity reached in 3 years. Mollusks Reproduction in Snails.
Some species have separate sexes, while others are hermaphrodites.
• The mud snail deposits flattened, transparent jelly capsules.
- 50-250 fertilized eggs in each capsule.
- 6-7 days egg hatches into swimming, ciliated larva (veliger).
• Large numbers of eggs produced because many get eaten.
http://life.bio.sunysb.edu/marinebio/westmeadow/ilyanassa.html Mollusks Gastropod Diversity.
Spiral shaped shells.
Flat shells Mollusks Gastropod Diversity.
The largest of the flat-shelled gastropods is the abalone (Haliotis).
• Inhabits the Rocky Pacific coast.
• Grazes on algae growing on rocks.
• Shells interior has a shiny rainbow pattern of colors (iridescence).
• Mantle secretes this pearly lustrous material (mother-of- pearl). Mollusks Gastropod Diversity.
Slipper shell (Crepidula).
• Filter feeder that strains microorganisms & organic debris from the water. Youngest
• Lives attached to hard substrates, including other organisms.
• As it grows it changes sex, male to female.
• Often found stacked, male on top Oldest females by generation below. Mollusks Gastropod Diversity.
Limpets inhabits rocky coasts.
• Graze on algae that cover rocks.
• Shell shaped like a slightly flattened cone.
• Keyhole limpets (Diodora) have a hole at the top of shell, which allows waste to exit.
http://naturediver.com/Gallery/Mollusca/Rough-Keyhole-Limpet-Diodora-aspera Mollusks Gastropod Diversity.
An unusual gastropod is the sea slug (Dendronotus), also called a nudibranch.
The sea slug & the sea hare (Aplysia) either lack shells or have reduced shells.
• Shy, membranous, beautiful creatures that glide along the seafloor.
https://www.dmt-nexus.me/forum/default.aspx?g=posts&t=2597 https://green2.kingcounty.gov/marine/Photo/Individual/23/44?photoId=53 https://mast.highline.edu/visit/aquarium/ 4 Mollusks Gastropod Diversity.
Nudibranchs.
• Breathe through skin & decorative tufts of gills on their backs.
• Feeds on hydroids & anemones.
- Absorbs stinging cells (nematocysts) as part of its own defense, stored in special projections.
• Dramatic color serves as a warning.
• Sea hares graze on algae; some turn green from chlorophyll.
• Some sea hares release dark ink to confuse & escape. Mollusks Complete the following pertaining to bivalves.
• Read pgs. 224-229 in the textbook.
• Complete the following section review questions in your “Section Review” worksheet.
1) Describe two different feeding methods of snails.
2) Compare the feeding methods of slipper shells & limpets.
3) By what means do sea slugs & sea hares breathe? Assessment MSS8-3.9 Mollusks Assessment 02
• Grab a copy of the assessment.
• Only using your knowledge of what you have learned complete the assessment.
• Once complete, raise your hand so I can collect your paper. Entry Task(s) Which of the following is the fastest of the mollusks?
What is the function of the structure labeled A in the marine animal shown below?
• Locomotion Mollusks Research: The Mind of a Mollusk
• Grab a copy of the article.
• Read the article thoroughly, highlighting or underlining key information about sponges.
• Answer the questions following the article.
Note: The “Research: The Mind of a Mollusk” worksheet can be located on the Marine Science webpage @ link: https://www.steilacoom.k12.wa.us/Page/6827 Entry Task(s) What does cephalopod mean?
• Head-foot
What makes cephalopods different from other mollusks?
• Streamlined body & lack an external shell Graphic Organizer How Are Cephalopods Adapted to Their Environment?
Instructions:
• Read through the introduction to the graphic organizer.
• Using pgs. 229-233 of the textbook, fill in the graphic organizer comparing & contrasting squid & octopuses.
• Also complete “Elusive Cephalopods” information.
Note: The “Cephalopods” graphic organizer can be located on the Marine Science webpage @ link: https://www.steilacoom.k12.wa.us/Page/6828 Entry Task(s) What is the difference between the arms & tentacles of cephalopods?
• Arms have suction disks that extend the entire length of the arm.
• Tentacles only have suction disks at the ends.
Thinking about the answer above, what distinguishing feature exists between a squid & octopus?
• Squid have 8 arms & 2 tentacles; octopuses have 8 arms only. Mollusks Structures of a Typical Cephalopod.
Arms & Tentacles.
• Capturing prey, killing it with a bite from their parrotlike beak.
- Octopus often inject paralyzing venom. Mollusks ReproductionStructures of ain Typical Snails. Cephalopod.
SomeArms &species Tentacles. have separate sexes, hermaphrodites. • Arms contain suction disks used for grasping & holding onto prey.
- Octopuses has 8 arms; Squid have 8 arms & 2 tentacles.
- Octopus also uses them for climbing & crawling along the seafloor.
Pg. 230 Mollusks Structures of a Typical Cephalopod.
Contain a one-way digestive tract.
Nutrients are distributed through a closed circulatory system. Mollusks Life Activities of Cephalopods.
What cephalopods lack in protection they make up in speed & other adaptations.
• Squid has a long, thin internal shell (“pen”) & is the fastest of all cephalopods.
- Swim in schools, providing additional protection.
Cephalopods use camouflage.
• Special pigment (chromatophores) that expand & contract changing skin pattern & color. Mollusks Life Activities of Cephalopods.
Have the ability to discharge a thick cloud of ink in defense.
Cephalopod’s intelligence & acute vision enhance their ability to seek prey, avoid predators, & communicate.
• Octopus brain & eyes are highly developed.
Pg. 230 Entry Task(s) What is the pen that squid have?
• A long, thin internal shell.
What are the chromatophores of cephalopods used for?
• Camouflage Mollusks Reproduction in Cephalopods.
Cephalopods breed in shallow waters (except nautilus).
• Separate sexes.
• Internal fertilization & external development.
• Male uses arm to deposit sperm packet within the mantle cavity of female. Mollusks Reproduction in Cephalopods.
Cephalopods breed in shallow waters (except nautilus).
• Squid female deposits clusters of fertilized eggs on rocks & shells.
- Most die after mating, leaving eggs to develop on their own.
- Young hatch after two weeks & emerge looking like miniature squid. Mollusks Reproduction in Cephalopods.
Cephalopods breed in shallow waters (except nautilus).
• Octopus female deposits clusters of fertilized eggs, attaching them to rocks & seaweed.
- Protects & cleans eggs, until they hatch (four months).
- Mother usually dies of starvation. Mollusks Elusive Cephalopods.
Chambered Nautilus.
• Inhabits the deep waters.
• Has an external shell.
- Spiral-shaped divided into compartments.
- Innermost compartments are gas-filled, regulates buoyancy.
- Lives in the outermost compartment.
• Has sticky tentacles (approx. 40-90). Mollusks Elusive Cephalopods.
Cuttlefish.
• Bottom dweller that feeds on invertebrates.
• Has an internal shell (cuttlebone).
- Either coiled or flat depending on the species.
• Like a squid, it has 8 arms & 2 tentacles. Mollusks Elusive Cephalopods.
Giant Squid, Architeuthis (“chief squid”).
• Largest swimming mollusk & largest invertebrate.
• Resembles the common squidsquid, but reaches lengths of about 20 meters.
• Inhabits the deep parts of the ocean (300-600 m)
• Preyed on by the sperm whale. Assessment MSS8-3.9 Mollusks Assessment_03
• Grab a copy of the assessment.
• Only using your knowledge of what you have learned complete the assessment.
• Once complete, raise your hand so I can collect your paper. Entry Task(s) List the similarities between the two organisms below.
• Mollusks • Cephalopods • Soft-bodies • Separate sexes • One-way digestive tract • Internal fertilization & external development. Mollusks What Are Some Other Types of Mollusks?
Chitons.
• Own class Polyplacophora (“many plates”)
• No eyes or tentacles.
• Eight overlapping shells
- Gives some flexibility. - Covers foot.
• Feeds like a snail, using radula to scrape algae off rocks. Mollusks What Are Some Other Types of Mollusks?
Tusk Shell (named for their tapered shell).
• Class Scaphopoda
• Live burrowed in sand.
• Long foot helps to anchor them.
• Have numerous long, thin tentacles with sticky ends.
- Capture tiny worms & plankton. - Push food to the mouth.
Pg. 234 Mollusks Complete the following pertaining to other mollusks.
• Read pgs. 234 in the textbook.
• Complete the following section review questions in your “Section Review” worksheet.
1) How is the chiton adapted to live in the rocky intertidal zone?
2) Describe the feeding method of the tusk shell.
3) In what kinds of environments do tusk shells live? Video National Geographic Documentary 2015 - Animal Planet 2015 HD Giant Pacific Octopus Documentary (44:00):
Synopsis: National Geographic documentary on the class, cephalopods, & their life functions
Link @ https://www.youtube.com/watch?v=E5EmjswFOzU Mollusks Chapter 9 Review.
• Pgs. 235-239 in the textbook.
• Answer Chapter 9 Review questions 1-26 on the worksheet provided.
- You will need to write in the answer from the textbook.
• Pages have been scanned & loaded as an assignment in google classroom (“MSS8-3.9 Assessment Review”).