Phylum Mollusca Flashcards

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.

True Signup and view all the answers

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

False Signup and view all the answers

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

True Signup and view all the answers

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

False Signup and view all the answers

Most clams have separate sexes.

True Signup and view all the answers

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

True Signup and view all the answers

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

Gastropoda Signup and view all the answers

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

Cephalopoda Signup and view all the answers

What class do chitons belong to?

Polyplacophora Signup and view all the answers

What class do tusk shells belong to?

Scaphopoda Signup and view all the answers

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

Bivalvia Signup and view all the answers

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

Cephalopoda Signup and view all the answers

What class of mollusk has no distinctive head?

Bivalve Signup and view all the answers

What classes of mollusk have an open circulatory system?

Gastropoda, Bivalvia, Chiton Signup and view all the answers

What class of mollusk has a closed circulatory system?

Cephalopod Signup and view all the answers

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

Gastropod & Cephalopod (Nautilus) Signup and view all the answers

What class of mollusk has all carnivorous species?

Cephalopod Signup and view all the answers

What class of mollusk uses radula in feeding?

Gastropod, Cephalopod, Chitons Signup and view all the answers

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

Bivalves Signup and view all the answers

What class of mollusk bites prey with a beak?

Cephalopod Signup and view all the answers

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

Chiton Signup and view all the answers

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

Cephalopod Signup and view all the answers

What class of mollusk uses excretory structures called nephridia?

Gastropoda, Bivalves, Chitons Signup and view all the answers

What class of mollusk are all marine species?

Bivalve, Cephalopods, Chitons Signup and view all the answers

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

Cephalopod Signup and view all the answers

What class of mollusk undergoes torsion?

Gastropod Signup and view all the answers

What class of mollusk swims by jet propulsion?

Bivalve (only scallops), Cephalopods Signup and view all the answers

What kind of shell does a squid have?

Internal degenerate shell Signup and view all the answers

Describe the foot of a cephalopod.

Modified to be arms that extend from the head Signup and view all the answers

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

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

What are some other animals in the cephalopod class?

Octopus, squid, cuttlefish Signup and view all the answers

What class do snails belong to?

Gastropods Signup and view all the answers

What shell do gastropods have?

Univalve shell Signup and view all the answers

Describe the foot of a gastropod.

Flat + strong. Signup and view all the answers

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

Used for crawling locomotion and it is highly muscular. Signup and view all the answers

What are some other animals in the gastropod class?

Sea slugs, abalones, cone shell Signup and view all the answers

What class does a clam belong to?

Bivalvia Signup and view all the answers

Describe the shell of bivalves.

Shell divided into 2 jointed halves. 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?

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

What are some of the other animals in Bivalvia?

Mussels, oysters, scallops Signup and view all the answers

Free swimming ciliated larva found in molluscs.

Trochophore Signup and view all the answers

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

Bilateral Signup and view all the answers

Layer of soft tissue that covers the visceral mass.

Mantle Signup and view all the answers

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

Shell Signup and view all the answers

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

Gills Signup and view all the answers

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

Torsion Signup and view all the answers

Feeding strategy used by bivalves.

Filter feeding Signup and view all the answers

Color-changing pigment cells that provide camouflage to cephalopods.

Chromatophores Signup and view all the answers

What is the only cephalopod to retain its external shell?

Nautilus Signup and view all the answers

What class contains snails, slugs, and nudibranchs?

Gastropoda Signup and view all the answers

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

Gastropoda, Cephalopoda Signup and view all the answers

The members of this class are free swimming predators.

Cephalopoda Signup and view all the answers

Members of this class have a radula.

Gastropoda, Cephalopoda Signup and view all the answers

This class has the most advanced nervous system.

Cephalopoda Signup and view all the answers

Members of this class have a trochophore larva.

Bivalvia, Gastropoda Signup and view all the answers

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

Cephalopoda Signup and view all the answers

Members of this class undergo torsion.

Gastropoda Signup and view all the answers

Members of this class have bilateral symmetry.

All Signup and view all the answers

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

Gastropoda Signup and view all the answers

All species in this class have two shells.

Bivalvia Signup and view all the answers

Members of this class are filter feeders.

Bivalvia and Cephalopoda Signup and view all the answers

Animals in this class have a closed circulatory system.

Cephalopoda Signup and view all the answers

Members of this class have an open circulatory system.

Gastropoda and Bivalvia Signup and view all the answers

Most members of this class have no shell.

Cephalopoda Signup and view all the answers

This muscular structure is used for burrowing into the sand.

Foot Signup and view all the answers

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

Adductor Signup and view all the answers

The opening into the digestive system.

Palps Signup and view all the answers

This structure connects the two valves.

Hinge Signup and view all the answers

Thin layer of epidermal tissue that covers the visceral mass.

Mantle Signup and view all the answers

These structures help direct food into the mouth.

Cilia Signup and view all the answers

Name given to sex organs.

Gonads Signup and view all the answers

Area where digested food is absorbed into the blood.

Intestine Signup and view all the answers

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

Incurrent siphon Signup and view all the answers

Site of digestion.

Stomach Signup and view all the answers

Shells are known by this name.

Valves Signup and view all the answers

This pumps blood through the open circulatory system.

Heart Signup and view all the answers

Opening leading out of the digestive system.

Anus Signup and view all the answers

Structures that are responsible for absorbing oxygen from the water.

Gills Signup and view all the answers

Structure through which water and wastes leave the clam.

Excurrent siphon Signup and view all the answers

Secretes enzymes responsible for the speedy digestion of food.

Digestive gland Signup and view all the answers

Made of calcium carbonate and provides protection to the clam.

Shell 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?

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

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

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. Signup and view all the answers

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

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. Signup and view all the answers

What adaptations allow cephalopods to be excellent predators?

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. Signup and view all the answers

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

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

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

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. Signup and view all the answers

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

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. Signup and view all the answers

How and why do cephalopods change color?

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

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

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. Signup and view all the answers

What is the outer layer of the shell?

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

What is the second layer of the shell?

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

What is the innermost layer of the shell?

Nacreous layer, nicknamed the mother of pearl layer, made of calcium carbonate. 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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Description

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.