PHYLUM: ________________________
CLASSES: 1. ___________________ 2. ___________________ 3.____________________
Mollusks were the first to develop a coelom (fluid-filled body cavity that develops within the mesoderm). They are the only coelomates without segmented bodies.
1. Body divided into ______ parts: ____________ (brain region), __________________(digestive organs & heart), and ____________ (locomotion).
2. Shell is formed by a membrane called the ____________. If an irritant like a grain of sand gets caught between the mantle & shell, the mantle secretes a __________. The shells are made of ____________ ____________________.
3. All organ systems are present. Nerve cord with nerve regions called ______________. Respiration through ____________ & the ___________. _________ circulatory system ( blood does not travel in vessels) in all except for octopuses & squids. _________________ digestive tract. Excretion by _______________. Separate sexes.
4. True body cavity - _________________.
5. _______________ symmetry or asymmetrical.
6. Habitat - ______________ or __________________.
7. Larval form has ___________ & is called a ___________________. Second free-swimming form is called a _________________.
8. Excretion through _____________________. These filter wastes from the coelom. They are great recyclers.
Wrapped around the visceral mass of mollusks is a heavy fold of tissue called the _____________. In aquatic snails, this is where the gills are. All mollusks except bivalves have a ___________________ which is a rasping tongue-like organ that may be used to scrape algae (snails) or as a weapon (cephalopods).
CLASSES
PELECYPODA – “hatchet foot” - ____ shells (bivalves) – examples - __________________________________Clams – held together by ________ adductor muscles – entirely encased in shell – no real head. These get food & oxygen by _____________________. Water enters the ____________ siphon , moves across the _______, and leaves through the _______________ siphon. __________ on the gills traps food & sends it from the ________ to the __________ and through the ____________. These have a ____ chambered heart. Scallops – have ___ adductor muscle & ________ along the mantle. They open & close their ________ to move. They reproduce sexually.
GASTROPODA – “stomach foot” – largest class – only have _____ shell --- examples _____________________ Shell is ________ & experiences torsion. These are able to detect light & shadows & reproduce with __________ fertilization. When snails are in water, they breathe through ________ & have ____ pair of tentacles. Those that live on land have _____ pairs of tentacles and are primarily active at _______ to prevent dessication. An _________ is a flat plate on the side of the foot which closes off the shell. These animals move by sliding over _____________. They feed using a tooth-like device called a ____________. It scrapes the food’s surface. Slugs are able to survive without snails.
CEPHALOPODA – “head foot” - most advanced class – examples __________________________________ These have a well developed head & tentacles. The nautilus also has an outer shell that it seals off each year signifying new growth. These animals have a ____________ circulatory system and well developed nervous system with many ganglia & a complex brain. All are _________________. The octopus can use ______________________ to move through the water (modification of the siphon). Squids have ____ tentacles, octopuses have _____, & nautiluses have _________. Reproduce sexually.