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Mollusks and Annelids Mollusks Characteristics Body Cavity: Mollusks have a true ____________, (first group to have). The gut and other internal organs are suspended from the body wall and cushioned by the __________ within. Symmetry: _______________ True coelom - diagram Mollusks body plan 3 part body plan: 1. visceral mass – center section with ____________ 2. Mantle – tissue fold that is outer layer and wraps around the ____________ mass like a cape 3. Foot – muscular regions, mainly _________________ Body plan diagram More characteristics Shell: 1 or 2 shells that serve as an ____________, composed of Calcium Carbonate Radula: all have except bivalves, ___________-like organ in mouth with backward-curving teeth Only coelomates ___________ segmented bodies Internal anatomy of a mollusk – diagram Organ system ____________– coelom is collection place waste, cilia pulls the fluid into nephridia (tubular structures for recycling useful substances), wastes leave through _________ the opens into the mantle Circulation – most _____chambered heart, open circulatory (octopuses and squids – closed) Respiration – In water: most have __________ in the mantle cavity, freshwater snails – _____________, Land have a primitive __________ Nephridium diagram Organ system con’t Reproduction: -Most have distinct ___________ / females -Some hermaphrodites -Oysters ________________ sex -Trochophore larvae Trochophore larva – diagram Gastropoda-c Snails / slugs, sea hare Aplysia-g reaches 1 m. Most gastropods have a ___________ shell Foot for locomotion Terrestrial secret ____________ from base of their foot Pair of tentacles on head with eyes located at the _________. Gastropods and food Herbivore – scrape ____________ Sea slugs, whelks and oyster use radula to bore holes in shells of other mollusks __________ shells the radula modified into poison- tipped harpoon. Humans eat: land _________- Helix – g , marine – ___________ Gastropod diagram Bivalvia-c Most marine _______-part hinged shell (valves – secreted by mantel), 2 thick ___________ muscles connect valves _______ distinct head region or radula, nerve ganglion above foot (simple brain), respond to light and touch External fertilization, free-swimming trochophore larvae, mussels in pouch in ______ Bivalves and food oysters / mussels human food ________ feeders: siphons (hollow _________) draws water in one side to go over gills and out other side Sticky mucus in gills – _______ food to which cilia direct to mouth (clams, oysters and scallops) Bivalve diagram Pearls Foreign ________ lodged between mantle and shell. Coats with thin sheets of _________(mother of pearl). Also on insides of shells. Layers added until completely enclosed In fine pearls the nacre has tiny, overlapping mineral crystals that act like __________, iridescence Best from Pinctada – g Pearl diagram Cephalopods -c Squids, octopuses, cuttlefish, nautiluses Means “____________”, “foot” Most no external shell (_____________ does) Giant squid largest invertebrate at 20m (65 ft) Large head attached to tentacles (divided foot), ___________ or hooks. Squids10, octopuses-8,nautilus – 80+ and has outer shell Most ________________ of invertebrates, complex nervous system, brain – discern shapes, eye with color vision Cephalopods moving Water in mantel cavity and out siphon – _________ propulsion Dark fluid (___________) to murky up water for escape. Cuttlefish ink is reddish brown (__________) used in paintings Cuttlefish “bones” used for birds to get ____________ Active marine predator: eat mollusks, crustaceans and worms Cephalopoda diagram Annelids - p 1mm to 3m (10 ft) Segmented – ring like structures along length of their body ________ – internal body walls separate the segments Anterior has cerebral ganglion, nerve cord underside (___________ body Coelom- large, fluid-filled, entirely in mesoderm Closed circulatory Respire through skin _____________ – excretory structures Annelids classified Setae – external ________________ paired on each segment ____________ – fleshy appendages Classification of the classes are based on the presence or lack of ____________ and ______________ Annelid diagram Polychaeta - c Marine worms, largest group, ________________ colors ______________ on each segment with setae on them, gas exchange due to increase surface area Burrowing, protective ____________ by harden secretions, tubeworms, feather duster – lives with only head out of tube (filter feeder) Nereis -g – free __________________ and strong jaws (predator) Polychaeta example Oligochaeta - c Earthworms – Lumbricus terrestris __________ parapodia and few setae on each segment Head region: no eyes but light / touch /moisture organ Respiratory exchange through _____________ (moist) Eat __________. Moves through one-way gut. Pharynx-crop (storage chamber) – gizzard (grinds soil) – intestines- anus and material out called ____________; aerates the soil Hermaphrodites Oligochaeta example Hydrostatic skeleton Fluid in coelom creates it Muscles that pull against: -_________________ muscles wrap around the segment -_________________ muscles span its length When circular muscles contract – worm _____________, longitudinal – worm ________________ up Hirudinea - c _____________ – bloodsucking due to suckers at both ends of its body (aquatic, terrestrial, some parasitic) ______________ setae and parapodia Flattened body Segments not separated internally Used in old days for ______________ Used today in _____________ reattachment surgery (microsurgery) to suck out accumulated blood, tissue remain healthy until new blood vessels can grow Saliva is anticoagulants – prevent _________________ and enzymes that break up blood clots. Hirudinea example