I. DiversityClass Polyplacophora means, “bearing many plates”.Chromatophores: pigment containing cellsGenerates changes in skin color in cold-blooded animals.Function in squid used for communication.Octopus uses it for camouflage for defense against predators.BIO SCI 100 1st Edition Lecture 10 Outline of Last Lecture I. Typical Cestode Lifecycle: Beef tapewormII. Rotifera and NematodeIII. Phylum RotiferaIV. Phylum NematodeV. Phylum MolluscaOutline of Current Lecture I. DiversityII. Land Snail AnatomyIII. Freshwater Clam AnatomyIV. Molluscs in Our LivesV. Invasive Species: Zebra MusselsCurrent LecturePhylum MolluscaI. DiversityClass Polyplacophora means, “bearing many plates”.- Chitons (common name) have shell with 8 articulating plates.- Marine intertidal zone; small, 2-5 cm.- Feeding: slowly moves across rocks, scraping algae with radula.Class Gastropoda means, “stomach-foot”.- Single shell, if any, may be coiled.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Aquatic or terrestrial.- Examples: Snails & Slugs.Nudibranchs means “naked-gills”.- Some nudibranchs have cerata, function in gas exchange and contain nematocysts (poison).- Nematocysts are obtained from eating cnidarians, and incorporated the nudibranch’s body as a defense mechanism.- Additional defense mechanism is Aposomatic coloration.- Feeding: use radula to scrape food.- Respiration: Internal gills (lungs).- Circulatory system: heart with few vessels.- Sensory: Cerebral ganglion and “eyes” at the end of stalks on head.- Locomotion: Foot is wide and on ventral of animal.II. Land Snail Anatomy:Nephridia HeartEyeGillsIntestineCerebral GanglionOvaries Mouth and RadulaTestes- Class Bivalvia means, ‘Two-shelled’.- No cephalization, simple sensory organs & no radula.- Aquatic (marine and freshwater).- Sedentary.- Burrows in sediments.III. Freshwater Clam Anatomy:Hinge ligament: open Adductor Muscles: closeFoot- Feeding: Food filtered from water brought in through incurrent siphon.- Respiration: Water moved across gills and out excurrent siphon.- Reproduction: Sperm from males is released into water and taken in by females; internal fertilization.Reproduction in Freshwater Bivalves- Clam larvae must get to gills of host fish to develop or die.- Some species, adult female clam, mantle edge mimics small fish.- Lures predatory fish.- When fish strikes, ‘eyespots’ rupture and release larvae onto fish’s gills.Class Cephalopoda: Examples: Octopus, cuttlefish, squid, nautilus.- Means “head-foot”.- Marine only.- Nervous system: advanced; large brain, complex eyes.- Respiration: Water brought into mantle cavity and passes over gills.- Feeding: All are predators: Eat fish, other molluscs, worms, crustaceans.- Octopus’ have: Arms, suckers, beak in mouth.- Locomotion: Foot is shaped into a funnel with the tentacles surrounding the mouth.- Expelling water from the mantle cavity out of the funnel (propulsion), helps in prey capture.- Squid and cuttlefish also commonly use propulsion.Cephalopod Shells- Shells are:o Lost: Octopus & squid.o Reduced: Cuttlefish (called a “cuttlebone”).o Present: Chambered Nautilus.Chromatophores: pigment containing cells- Generates changes in skin color in cold-blooded animals.- Function in squid used for communication.- Octopus uses it for camouflage for defense against predators.Giant Cephalopods- Giant Squid: Lives in the deep ocean, up to 43 feet long including 27 feet of tentacles.- Giant Clams: Lives in shallow coral reefs up to 4 feet across and weigh up to 500 pounds.- Blue-ringed Octopus; small but deadly; Marine.- Secretes poison into saliva from two glands:o 1 type for food acquisition—crabs.o 1 type for predator defense—neurotoxin. Can kill humans; no known antidote.IV. Molluscs in our lives- Gastropods Producing Pearls: oysters.- An irritant is lodged between the mantle and the shell.- Oyster covers irritant with many layers of nacre (mother of pearl).- Food: calamari, oysters, clams.V. Invasive Species: Zebra mussel- Freshwater.- Introduced to Great Lakes in the 1980's via transoceanic ship ballast water.- Native to Russia.o Problems:  Kills native clams. Colonizes surfaces. Clog water intake