Phylum Mollusca

Class: Gastropoda

Class: Bivalvia

Class: Cephalopods

Class Gastropoda

Snails, Limpets and Slugs

Gastropoda• Planning on being rich and

famous?• Wining and dining at the

most expensive restaurants?

• Romantic trips to Paris? • Ever wonder what Ceaser

munched on after long hard days ruling the roman empire?

• Than you should be familiar with ESCARGOT!!!!

General Body Plan: Gastropod

• 1. Head foot• Head: sensory nerves,

mouth – Anterior: near the

head/mouth

• Foot: attachment and locomotion – Posterior: near the anus– Flattened w Cilia:

locomotion

That slimy foot… • Snail Slime:

– Suction power: travel up and down trees

– Escape: Emit a nasty tasting slime when threatened

– Movement: Allows them to easily squeeze through tight spaces

– Water Retention

• How Ms. Cota looks so young: – Skin regenerating – used in skin beauty products

General Body Plan of mollusks

• 2. Visceral Mass– Organs of

digestion – Circulation – Reproduction – Excretion – Dorsal to the

head foot

General Body Plan: Gastropod

• Mantle (shell) – Attached to visceral

mass• Encloses most of the

body

– Protection

• Mantle Cavity: – Gas exchange– Elimination of digestive

wastes – Release of reproductive

products

Respiration

• One Gill in mantle cavity – Oxygen is taken in – Diffused through the cells

• Open Circulatory System – Pushes blood in to

expand– Pulls it out to contract

General Body Plan: Mollusca

• Radula: Scraping mouth – Chitinous belt & curved

teeth • Covers fleshy tongue • Muscles move it back

and forth • Conveyor belt

• Digestion – Scrape algae– Enzymes break down

food in stomach

CFU

• How do mollusks exchange gasses – Filter air through their gills

• Where are these gills located?– The mantel

• What is the structure called that scrapes up food?– A Radula

• All mollusks have: – A visceral Mass – A head foot – A mantel

Reproduction

• Monoecious: can be whatever sex they want! – Internal cross

fertilization – One snail acts as

female one acts as male

– Deposit eggs in gelationous strings

Class Bivalvia

Clams, Oysters, Mussles, Scallops

Bivalvia!

• Edible• Commercial value:

Form Pearls • Valuable in removing

bacteria from polluted water! – Rely on water currents to

get food – Filter in nutrients, filter out

clean water

• Valuable food source: humans, raccoons, otters, birds

Structure

• Two halves of a shell: Valves – Adductor muscles hold

valves shut

• Visceral Mass• Mantel Cavity• Gills • Cilia• Siphon:

– filters water in and out of shell

Foot

• Most mollusks have foot that can be used differently – Attach mollusk to

surface – Act as a lure to

attract prey – Surround organs for

safety

Respiratory System

• Respiration and digestion: – Incurrent siphon and

gills

CFU • What is the technical term for the two halves of the

shell?– Valves

• What structure filters water in and out of the shell – Siphon

• What is the function of the foot – Attach mollusk to substrate, act as lure

• Why are bivalves important to humans?– Pearls, food source, pollution filter

• How are humans affecting bivalves? – Over harvesting, pollution, loss of current

Mollusks: Cephalopods Octopus, Squid, Cuttlefish

Cephalopods

• Fierce Predators – Large brains – Complex sensory structures – Rapid locomotion – Grasping tentacles

• Octopus vs. Shark

Locomotion

• Jet like propulsion out of mantle – Squid: uses it for

catching prey • Up to 25 mph!

– Squid catching cameras.

– Octopus: escape method

Nervous/Sensory System

• Very large brain – Dedicated to

movement/control of tentacles

– Very smart: octopus are known to problem solve

– Curious

• Giant Octopus• Octopus Opening lid • Eyes: advanced, similar to

vertebrate eyes – Convergent evolution

Predator Adaptations

• Locate prey by sight• capture prey w tentacles/

suction cups – Tentacles reinforced w

protein

• Eat using a radula – Cuttlefish: small

invertebrates

– Octopus:• Nocturnal: snails, fish,

crustations

Predator Adaptations

• Chromatophores – Cells that can change colors

• Tiny muscles contract or expand and chromatophores quickly change color– Alarm response– Defensive – Blend in w environment– Courtship – Bioluminescence

• Cuttlefish in love