Phylum Mollusca

Phylum Mollusca • ___________________ symmetry• Body Cavity - ___________________• Body has three distinct regions

– _________________ - central section, which contains the body's organs

– ____________ - Means “cloak” in Greek. Wraps around the visceral mass, secretes shell. Mantle cavity -space between mantle & visceral mass.

– ________________ - Ventral, muscular and prominent.

• Functions: – Locomotion - Bivalvia use to dig into sand– Securing food - modified into a tentacle in Cephalopods

Digestive System

• _______________- rasping organ in Gastropods, Beak in CephalopodsAll mollusks except Bivalvia have this structure.

• Used to scrape algae off rocks (Gastropoda) or as a weapon to puncture holes in prey (Cephalopoda)

• Has mouth, esophagus, stomach, intestine and anus.

• Digestive gland secretes ______________ into the gut.

Excretory System

• __________________ wastes dumped into coelom. Cilia in nephridium cause fluid (wastes and nutrients) to move through nephridia.

• Nutrients are _________________; wastes empty into the mantle, then removed.

Circulatory System

• __________________________ for all except Cephalopoda.

• ______________________ - Coelom - restricted to the region around the Dorsal Aorta.

Respiratory System

• ___________ located in their mantle cavity

• ____________ beat continuously causing a steady stream of _________ to pass over the gills. Gills also trap ___________

Nervous System

• Ring of ___________________ around esophagus

• Two sets of ventral ________________

• Nerve fibers maybe quite large - ________

• __________________, _______________

and ________________ receptors

Reproductive System

• Male and female

• ___________________ fertilization

Major Classes

• Class _____________________

• Class _____________________

• Class ______________________

• Class ______________________

Class _______________ - Snails and slugs

• Examples: ________________ - Sea slugs • _________________ secretes hard

protective ____________.• Some don't have shell.• All _________________ mollusks are in

this class, but most members are __________.

• Terrestrial mollusks don't have ___________.

Class Gastropoda - Snails and slugs

• Uses _________________ to scrape algae for food

• ______________ adapted for locomotion. It forms a slimy path then ungulates foot (wave like motion)

• ______________ are located on a pair of stalk like tentacles on the head

Class ________________ - Clams, oysters and scallops

• Examples - ___________________________, • Name means: bi - “______", valva -

“_________________________"• Edge of _______________ secretes a two part

hinged shell. Composed of __________________________. Shell shows _________________ lines.

• No distinct ____________ region, but have a central ________________ above foot

• Most are _______________, exception scallops and shipworms. Most are __________________

Class Bivalvia• Nervous System- touch and ______________• _____________________ System • _______________________ connect the two

valves together.• ________________________ used to dig into the

sand and locomotion• Nutrition - __________________________. • Use a hollow tube called a ________________ to

pull in water. Water is then drawn over the _________ then out the ___________________ siphon.

Class Bivalvia• Reproduction • ______________, Most species have separate

sexes, few hermaphrodites. Shed ________ and _________ into water. Fertilization is ______________.

• _________________ develops into a free swimming ____________________ larva.

• Teredo (_____________) - feeds on ______________ that it ingests

Class _____________________ - chitons

• Shell is embedded in _______________

• Mantle cavity has two lateral grooves on each side of body where gills are located.

• Use _______________ to scrap algae

• Reproduce __________________, Separate sexes

____________________ feet)Invertebrate

Cephalopods History

• appeared some time in the late ____________ several million years before the first primitive fish began swimming in the ocean

• Scientists believe that the ancestors of modern cephalopods (Subclass Coleoidea: octopus, squid, and cuttlefish) diverged from the primitive externally shelled Nautiloidea (Nautilus) very early - perhaps in the Ordovician, some 438 million years ago.

Cephalopod Hist. cont

• Cephalopods were once one of the dominant life forms in the world's oceans

• Today there are only _______ or so living species of cephalopods (compare that with 30,000 living species of bony fish).

• However, in terms of productivity, some scientists believe that cephalopods are still giving fish a run for their money

_____________________

• __________ swimming predatory animals

• Extremely ____________________

• Cephalopods foot is divided into tentacles– squid=____ tentacle– octopus=_____ tentacle– cuttle fish=_____or more tentacle

Cephalopods distinct structures

• Cephalopods have large, well developed ________ that form images

• Tentacles are covered with _____________ for seizing and holding prey

• Cephalopods have a _________ like structure in their digestive tract called a ______________ for breaking down food

• Cephalopods mouth has two strong ______________ for tearing its prey apart.

• Cephalopod is fitted with a ____________ like structure that fills with water and ejects it acting like a ____________________________

Cephalopods masters of deception

• Able to change _________________• Can expand and contract _____________

cells in its _________• _____________________(color cells) give

the cephalopod the ability to change. • Can eject _____ when alarmed causing the

enemy to be temporarily blinded. The ink also inactivates predators chemical receptors used for detecting prey.

Cephalopods Diet

• Feed on crabs, shrimp, fish, and other cephalopods

Cephalopods Habitat

• ____________ to ___________

• Polar to tropics

• In other words they are found __________________

Giant Squid

• Giant squid get up to _____ feet (20 m) in length and easily hold the record as the ________________________________

• Despite the size of these beasts no one has ever seen one alive in its natural environment

• Main Diet of the __________________• Giant squid were once mistaken for sea

monsters in sailing days