Transcript Mollusks - Nutley Public Schools

“SOFT-BODIED”
EXAMPLES:
Snails
Clams
Squid
GENERAL CHARACTERISTICS
• 110,000 species (2nd
largest phylum)
• Primarily Marine
• Bilateral Symmetry
• Have organs and
organ systems
GENERAL MORPHOLOGY
• Soft Body (3 Regions)
• Head
– Mouth and
Sense Organs
• Foot
– Crawling,
Burrowing,
Swimming
• Visceral Mass
– Organs
• Calcium Carbonate Shell
• Feeding & Digestion
- Separate mouth and anus
- Radula - Tongue like
structure with fine teeth to
scrape
• Nervous System
Clusters of nerves or complete brain (Cephalapods)
Reproduction
Separate males & females
Used as wampum by Native Amer. (quahog clam)
Personal Adornment
Shell Industry (harvests live animals)
Mariculture: major food source (mussels, oysters)
Music (conch) & Art
Pearls
Medical – cone shell venom used to treat strokes
Mediterranean Rock Whelk (Murex) used for purple dye by
ancient Romans (12,000 mollusks to dye 1 garment)
MOLLUSK CLASSES
Gastropods (Univalves)
• “Stomach Foot”
• Ex: snails, whelks,
abalone, nudibranchs
(shell-less)
• Single spiral valve (shell)
• Operculum – covers opening
• 75% all mollusks in this class
• Benthic, SW, FW, &
Terrestrial
• Herbivores or
Carnivores; Radula
• Some toxic species
– Cone Shells
Pelecepods (Bivalves)
• “Bivalves” (2 Shells)
Hinged by ligaments and
adductor muscles
• Ex: clams, oysters,
scallops, mussels
• Giant clam video
• Sessile & benthic; no head; no radula
• Body lies completely
inside the mantle cavity
• Filter Feeders
– Incurrent Siphon
• Water, Food & O2 In
– Excurrent Siphon
• Water & Waste Out
- Trap food on gill mucus
Burrowing Bivalves
• Clams
– Hatchet shaped foot
adapted for burrowing
• Shipworm
– Worm-like bivalves
that burrow into wood
Non-Burrowing Bivalves
• Mussels
– Byssal threads secreted to
hold mussel in positon
• Scallops
– Motile Bivalve that uses jet
propulsion to move
• Oysters
– Secrete cement substance
that adheres to a substrate
Giant Clam
Scallop Eyes
Cephalopods (“Head Foot”)
• Ex: squid, octopus, nautilus, cuttlefish
Characteristics
• Reduced shell; internal
support cartilage
• Complex Nervous System
(Brain)
• Well Developed Eyes
• Foot Modified Into
Tentacles/Arms w/suckers
• Locomotion via Jet
•
•
•
Propulsion (suck in water
& spit)
Changes Colors via
Chromatophores
Carnivores - Have beaklike jaws & poisonous bite
Ink Gland for protection
Octopus
Squid
Cuttlefish
Nautilus
GIANT & COLLOSAL SQUID
http://news.bbc.co.uk/2/hi/science/nature/2910849.stm
2003
http://news.nationalgeographic.com/news/2005/09/0927_050927_giant_squid.html
http://news.mongabay.com/2006/1222-squid.html
2006
2005