Test 6 - Complex Animals - Mollusks

2025-07-29

What rank are mollusks in terms of which phylum has most numbers of living animals

2nd to arthropods

what does mollis mean

soft

body cavity status and what is it lined with.

coelomates with a body cavity lined with mesodermal tissue

are mollusks protosomes and what are protosomes

Yes, proto(first)some(stoma = mouth), mouth forms before anus. Blastopore becomes the mouth

Look & memorize

Yay! Good job, now do 20 pushups

Look & memorize

Yay, now do 30 sit ups

what three body parts do all mollusks have

mantle foot and visceral mass

Describe digestive system (4)

• one way

• specialized organs

• specialized mouthparts

• radule (chitinous tongue)

describe circulatory systm

all open except cephalopods

describe respiration system

gills extract O2 & get rid of nitrogenous waste

What do most mollusks have for protection for their soft bodies

CaCO3 shell, internal shells, or lost to evolution

what type of symmetry

bilateral

nervous system?

cephalized & sensory organs

how reproduce

dioecious, sexual

describe visceral mass

contains gut (mouth&anus), circulatory system, reproductive system, and excretory system with kidneys

describe mantle (3)

• thin membrane covering visceral shell and secretes mass, possesses chemical sensory organs.

• mantle cavity encloses and protects gills.

• can be lined with chromatophores.

describe strong muscular foot

foot modified to suit individual species lifestyles, e.g. squid = siphon

radula feeding (3)

• shape depends on feeding method and type of food

• herbivores, carnivores, or detritovores

• different radulae used for drilling, scraping, multipurpose, darts, and secreting poison

siphon (4)

• respiration: brings water to gills

• feeding: transports food to digestive system

• reproduction: brings in sperm, releases eggs or sperm

• locomotion: jet propulsion (nautilus)

open circulation in mollusks (5)

• all but cephalopods

• pumps hemolump throughout body

• no veins

• brains to and from the gills

• slow

closed circulation in mollusks

• cephalopods

• pumps hemocyanin through veins using vessels

How many shell plates does polyplacophora have, and what can it do (4)

8:

• protection

• flexing

• ball rolling

• sounded by girdle structure

where do polyplacophora live

interidial zone

what is the polyplacophora foot for

adhesion

describe the polyplacophora radula and what it does

radula tipped with magnetide (Fe₃O₄) to eat algae

Examples from class bivalvia

clams, mussels, oysters

example of polyplacophora

chitons

what does valvia mean

shell

Do bivalva have radulas, why or why not

no radula, because filter feeders

what keeps bivalva closed

abs

what is the bivalva foot used for

burrowing

how do scallops move

jet propulsion

examples from class gastropoda

snails, limpets, slugs

How are gastropoda and Papua New Guinea similar

most diverse class

describe gastropoda foot and muscle movement

large muscular foot, muscles move in rippling motion

gastropoda shells

• some univalves, some no-valved

• most shells coiled, coloured, textures

visceral mass of gastropoda description

visceral mass is turned 180, and allows head to go into shell

Most snails have a lid-like part called an…

operculum on the back of the foot, so they can draw their bodies into their shell and close off the opening

physical description of gastropoda

• well defined head

• 2-4 tentacles

• eyes or sensory cells

reproduction in gastropodas

dioecious, external fertilization

respiratory system of gastropodas

most gills, some lungs

gastropoda radula

specialized, to get food

symmetry of cephalopoda

bilateral

physical components & structures of cephalopoda

• prominent head

• arms

• tentacles

what are cephalopoda known for…

intelligence, developed brain, only other than chordates that have true brains

what do cephalopoda arms do

take in food surounding a hard, strong, beak-like jaw that tears the prey and secrete a poison to paralyze it

how does cephalopoda move

jet propulsion

unique adaptations of cephalopoda

• chromatophores

• advanced vision

• ink cloud when in danger

what is jet propulsion

• a method of movement where an animal expels fluid forcefully in one direction to propel itself in the opposite direction

• based on Newton’s Third Law (for every action, there is an equal and opposite reaction).

Why are feathery gills good for diffusion

• increase surface area for gas exchange

List all functions of parts

Arms – Grasp and manipulate prey; covered with suckers.

Funnel (Siphon) – Expels water for jet propulsion and removes waste.

Mantle – Muscular body wall; encloses organs and helps draw in and expel water for movement.

Ink Sac – Releases ink through the funnel to distract predators.

Excretory Pore – Releases waste from the body.

Fin – Stabilizes and steers while swimming.

Eye – Detects light, shape, and movement; enables advanced vision.

Cartilages – Provide support and structure for the head and eyes.

Anus – Expels digestive waste into the mantle cavity.

Gill – Site of gas exchange (oxygen in, CO₂ out).

Gill Heart (Branchial Heart) – Pumps blood to the gills for oxygenation.

Visceral Mass – Contains internal organs (digestive, reproductive, excretory systems).