Phylum Mollusca Flashcards
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Questions and Answers

All members of the phylum Mollusca have radial symmetry.

False

A flexible tongue-like structure with abrasive teeth that point backward is called a chromatophore.

False

Mollusks are divided into classes based on the characteristics of their foot.

False

Nudibranchs are marine gastropods that lack a shell.

<p>True</p> Signup and view all the answers

Bivalves are the only molluscs that do not possess a foot.

<p>False</p> Signup and view all the answers

Bivalves lack a distinct head and there are no specialized sense organs.

<p>True</p> Signup and view all the answers

The fertilized egg of a clam develops into a pinnula larva.

<p>False</p> Signup and view all the answers

Most clams have separate sexes.

<p>True</p> Signup and view all the answers

Cephalopods have a complex brain and well-developed sense organs.

<p>True</p> Signup and view all the answers

What class do nudibranchs, snails, and slugs belong to?

<p>Gastropoda</p> Signup and view all the answers

What class do squid, octopus, nautilus, and cuttlefish belong to?

<p>Cephalopoda</p> Signup and view all the answers

What class do chitons belong to?

<p>Polyplacophora</p> Signup and view all the answers

What class do tusk shells belong to?

<p>Scaphopoda</p> Signup and view all the answers

What class do clams, oysters, scallops, and mussels belong to?

<p>Bivalvia</p> Signup and view all the answers

What class of mollusk is intelligent, with a well-developed nervous system?

<p>Cephalopoda</p> Signup and view all the answers

What class of mollusk has no distinctive head?

<p>Bivalve</p> Signup and view all the answers

What classes of mollusk have an open circulatory system?

<p>Gastropoda, Bivalvia, Chiton</p> Signup and view all the answers

What class of mollusk has a closed circulatory system?

<p>Cephalopod</p> Signup and view all the answers

What class of mollusk has external shells present in some species?

<p>Gastropod &amp; Cephalopod (Nautilus)</p> Signup and view all the answers

What class of mollusk has all carnivorous species?

<p>Cephalopod</p> Signup and view all the answers

What class of mollusk uses radula in feeding?

<p>Gastropod, Cephalopod, Chitons</p> Signup and view all the answers

What class of mollusk all use gills for both respiration and food collection?

<p>Bivalves</p> Signup and view all the answers

What class of mollusk bites prey with a beak?

<p>Cephalopod</p> Signup and view all the answers

What class of mollusk has a shell that contains 8 overlapping plates on the dorsal surface?

<p>Chiton</p> Signup and view all the answers

What class of mollusk has a pair of tentacles on their head?

<p>Cephalopod</p> Signup and view all the answers

What class of mollusk uses excretory structures called nephridia?

<p>Gastropoda, Bivalves, Chitons</p> Signup and view all the answers

What class of mollusk are all marine species?

<p>Bivalve, Cephalopods, Chitons</p> Signup and view all the answers

What class of mollusk is known for their great camouflage abilities?

<p>Cephalopod</p> Signup and view all the answers

What class of mollusk undergoes torsion?

<p>Gastropod</p> Signup and view all the answers

What class of mollusk swims by jet propulsion?

<p>Bivalve (only scallops), Cephalopods</p> Signup and view all the answers

What kind of shell does a squid have?

<p>Internal degenerate shell</p> Signup and view all the answers

Describe the foot of a cephalopod.

<p>Modified to be arms that extend from the head</p> Signup and view all the answers

What purpose does the foot of a cephalopod serve? How is the foot adapted for this purpose?

<p>Capturing prey and locomotion. Suction cups for grabbing prey; long and mobile.</p> Signup and view all the answers

What are some other animals in the cephalopod class?

<p>Octopus, squid, cuttlefish</p> Signup and view all the answers

What class do snails belong to?

<p>Gastropods</p> Signup and view all the answers

What shell do gastropods have?

<p>Univalve shell</p> Signup and view all the answers

Describe the foot of a gastropod.

<p>Flat + strong.</p> Signup and view all the answers

What is the foot of a gastropod used for and how is it adapted for this?

<p>Used for crawling locomotion and it is highly muscular.</p> Signup and view all the answers

What are some other animals in the gastropod class?

<p>Sea slugs, abalones, cone shell</p> Signup and view all the answers

What class does a clam belong to?

<p>Bivalvia</p> Signup and view all the answers

Describe the shell of bivalves.

<p>Shell divided into 2 jointed halves.</p> Signup and view all the answers

Describe the foot of a bivalve. What purpose does it serve? How is this foot adapted for its purpose?

<p>Foot is ventrally located and is used for burrowing and locomotion. Foot retractor muscles to move the foot.</p> Signup and view all the answers

What are some of the other animals in Bivalvia?

<p>Mussels, oysters, scallops</p> Signup and view all the answers

Free swimming ciliated larva found in molluscs.

<p>Trochophore</p> Signup and view all the answers

Body symmetry in which the right and left sides mirror one another.

<p>Bilateral</p> Signup and view all the answers

Layer of soft tissue that covers the visceral mass.

<p>Mantle</p> Signup and view all the answers

Structure made of calcium carbonate that protects the soft bodies of some mollusks.

<p>Shell</p> Signup and view all the answers

Structures found in aquatic molluscs that are specialized for gas exchange.

<p>Gills</p> Signup and view all the answers

The process occurs during gastropod larval development and results in the 180-degree twisting of the visceral mass.

<p>Torsion</p> Signup and view all the answers

Feeding strategy used by bivalves.

<p>Filter feeding</p> Signup and view all the answers

Color-changing pigment cells that provide camouflage to cephalopods.

<p>Chromatophores</p> Signup and view all the answers

What is the only cephalopod to retain its external shell?

<p>Nautilus</p> Signup and view all the answers

What class contains snails, slugs, and nudibranchs?

<p>Gastropoda</p> Signup and view all the answers

Members of this class have a body plan consisting of a head, foot, and visceral mass.

<p>Gastropoda, Cephalopoda</p> Signup and view all the answers

The members of this class are free swimming predators.

<p>Cephalopoda</p> Signup and view all the answers

Members of this class have a radula.

<p>Gastropoda, Cephalopoda</p> Signup and view all the answers

This class has the most advanced nervous system.

<p>Cephalopoda</p> Signup and view all the answers

Members of this class have a trochophore larva.

<p>Bivalvia, Gastropoda</p> Signup and view all the answers

This class contains animals whose foot is divided into arms and tentacles.

<p>Cephalopoda</p> Signup and view all the answers

Members of this class undergo torsion.

<p>Gastropoda</p> Signup and view all the answers

Members of this class have bilateral symmetry.

<p>All</p> Signup and view all the answers

Members of this class have most species having only one shell but some have none.

<p>Gastropoda</p> Signup and view all the answers

All species in this class have two shells.

<p>Bivalvia</p> Signup and view all the answers

Members of this class are filter feeders.

<p>Bivalvia and Cephalopoda</p> Signup and view all the answers

Animals in this class have a closed circulatory system.

<p>Cephalopoda</p> Signup and view all the answers

Members of this class have an open circulatory system.

<p>Gastropoda and Bivalvia</p> Signup and view all the answers

Most members of this class have no shell.

<p>Cephalopoda</p> Signup and view all the answers

This muscular structure is used for burrowing into the sand.

<p>Foot</p> Signup and view all the answers

These powerful muscles are used to open and close the valves.

<p>Adductor</p> Signup and view all the answers

The opening into the digestive system.

<p>Palps</p> Signup and view all the answers

This structure connects the two valves.

<p>Hinge</p> Signup and view all the answers

Thin layer of epidermal tissue that covers the visceral mass.

<p>Mantle</p> Signup and view all the answers

These structures help direct food into the mouth.

<p>Cilia</p> Signup and view all the answers

Name given to sex organs.

<p>Gonads</p> Signup and view all the answers

Area where digested food is absorbed into the blood.

<p>Intestine</p> Signup and view all the answers

Structure through which water, food, and oxygen enter the clam.

<p>Incurrent siphon</p> Signup and view all the answers

Site of digestion.

<p>Stomach</p> Signup and view all the answers

Shells are known by this name.

<p>Valves</p> Signup and view all the answers

This pumps blood through the open circulatory system.

<p>Heart</p> Signup and view all the answers

Opening leading out of the digestive system.

<p>Anus</p> Signup and view all the answers

Structures that are responsible for absorbing oxygen from the water.

<p>Gills</p> Signup and view all the answers

Structure through which water and wastes leave the clam.

<p>Excurrent siphon</p> Signup and view all the answers

Secretes enzymes responsible for the speedy digestion of food.

<p>Digestive gland</p> Signup and view all the answers

Made of calcium carbonate and provides protection to the clam.

<p>Shell</p> Signup and view all the answers

Label the structure.

<ol> <li>Foot, 2. Valve, 3. Growth range, 4. Siphons, 5. Umbilical, 6. Hinge ligament</li> </ol> Signup and view all the answers

Label the structures.

<ol start="7"> <li>Heart, 8. Intestine, 9. Shell, 10. Mantle, 11. Posterior abductor muscle, 12. Excurrent siphon, 13. Inccurrent siphon, 14. Anus, 15. Gills, 16. Gonad, 17. Foot, 18. Palps, 19. Mouth, 20. Stomach, 21. Digestive gland, 22. Anterior adductor muscle</li> </ol> Signup and view all the answers

What is the composition of a mollusc shell? What are the different layers of a mollusc shell? How is the shell made? What structure(s) help to make the shell?

<p>Mollusks are made up of calcium carbonate shells; it is secreted by the mantle. The 3 layers are the peristracum, prismatic, and nacreous.</p> Signup and view all the answers

Describe the difference in feeding methods among gastropods, cephalopods, and bivalves.

<p>Bivalves eat by filter feeding through the gills; Gastropods can eat on algae, kelp, extend proboscis to find food, and are scavengers, deposit, and filter-feeders. Cephalopods use tentacles and beak-like jaws (radula) to eat food.</p> Signup and view all the answers

Relate the type of movement with the structure of the foot in the snail, clam, and squid.

<p>Squids use jet propulsion; Snails propel themselves by deforming a layer of mucus beneath it via contractions in its foot muscle; Clams burrow with their foot.</p> Signup and view all the answers

What adaptations allow cephalopods to be excellent predators?

<p>They have a ring of tentacles, internal structures, and suckers. Also have ink fluid (sepia) and degenerated shells (pen), which can be used as weapons for distraction.</p> Signup and view all the answers

In what ways are cephalopods more advanced than the other classes of molluscs?

<p>They have a large cylindrical body with 10 appendages (includes a pen). They have a closed circulatory system and suckers for hunting.</p> Signup and view all the answers

What roles do molluscs play in the ecosystem? State three examples.

<p>Mollusks serve as an important food source for birds and mammals, help filter the water, and play a role in soil regeneration and nutrient recycling.</p> Signup and view all the answers

List and describe the three main parts of the molluscan body plan.

<p>Mollusks have a head, visceral mass, and a foot. The head contains sensory organs, the visceral mass has organ systems, and the foot is used for locomotion.</p> Signup and view all the answers

How and why do cephalopods change color?

<p>They have chromatophores, which are skin cells for pigment that can alter color.</p> Signup and view all the answers

List three or more ways the nautilus is different from other cephalopods.

<p>Nautilus has a large coiled shell divided into chambers, their head has 60-20 tentacles coated with sticky substances, and they dwell on the bottom during the day and float closer to the surface at night.</p> Signup and view all the answers

What is the outer layer of the shell?

<p>Periostracum made of protein called conchiolin, protects the shell from dissolution and boring animals.</p> Signup and view all the answers

What is the second layer of the shell?

<p>Prismatic layer made up of calcium carbonate and protein, makes up the bulk of the shell.</p> Signup and view all the answers

What is the innermost layer of the shell?

<p>Nacreous layer, nicknamed the mother of pearl layer, made of calcium carbonate.</p> Signup and view all the answers

Study Notes

Phylum Mollusca Overview

  • Members exhibit bilateral symmetry, not radial symmetry.
  • Distinctive structures include the radula (a tongue-like organ for feeding) and the mantle (tissue covering the visceral mass).

Classes of Mollusca

  • Gastropoda: Includes slugs, snails, and nudibranchs; exhibit torsion during larval development; utilize a radula for feeding.
  • Cephalopoda: Includes squids, octopuses, and cuttlefish; possess a closed circulatory system; highly developed nervous system; capable of jet propulsion.
  • Bivalvia: Comprises clams, oysters, and mussels; have shells divided into two halves; use gills for filter feeding.
  • Polyplacophora: Chitons characterized by eight overlapping plates on the back.
  • Scaphopoda: Known as tusk shells.

Anatomical Features

  • Foot: Serves various purposes—burrowing in bivalves, movement in gastropods, and modified into arms in cephalopods.
  • Shell Structure: Composed of three layers:
    • Periostracum: Outer protein layer protecting from erosion.
    • Prismatic Layer: Main structure made of calcium carbonate.
    • Nacreous Layer: Inner layer known as mother of pearl.

Feeding and Respiration

  • Feeding Strategies:
    • Gastropods utilize radula to scrape surfaces for algae; some are scavengers.
    • Bivalves filter feed using gills for both respiration and food collection.
    • Cephalopods are carnivorous, using tentacles and beaks for capturing prey.

Reproductive Features

  • Most clams have separate sexes; fertilization involves development through trocophore larvae.
  • All mollusks possess gonads, responsible for reproduction.

Ecological Roles

  • Mollusks play vital roles in ecosystems as food sources for various organisms, including birds and mammals; contribute to nutrient recycling and soil regeneration.

Adaptations

  • Cephalopods exhibit advanced adaptations, including chromatophores for color changes, enhancing their ability to camouflage and communicate.

Movement

  • Squids utilize jet propulsion for swift movement, snails crawl using muscular contractions, and clams burrow into the substrate with their foot.

Unique Class Characteristics

  • Cephalopoda: Characterized by intelligence and complex behavior; possess varied tentacle structures adapted for predation.
  • Gastropoda: Display a wide range of forms and can be found in marine, freshwater, and terrestrial environments; most species feature a spiral shell.

Special Features

  • Nautilus has a distinctive coiled shell; differs from other cephalopods by having a chambered structure and nocturnal behavior.
  • Advanced nervous systems in cephalopods facilitate learning and memory, distinguishing them from other mollusks.

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Test your knowledge of the phylum Mollusca with these flashcards. Each card presents a statement regarding mollusks, where you'll determine its accuracy. Perfect for students and enthusiasts looking to deepen their understanding of these fascinating creatures.

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