Ch 27 Mollusks and Annelids Flashcards

1
Q

what is phylum mollusca

A
  • phylum Mollusca
  • evolved 600 million years ago
  • 100 000+ species
  • 7 classes
  • live across the world
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2
Q

what are Mollusks

A
  • soft bodied animals that all have either an internal or external shell, aside from octopodes
  • they have larva called trochophores which they share with annelids, trochophores are aquatic
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3
Q

what are the four body parts of mollusks

A
  • 4 parts: Foot, Mantle, Shell, and Visceral mass
    • the foot assists with eating and has the mouth, also facilitates movement
    • the mantle is a layer of tissue that covers the body
    • the shell is made of calcium carbonate and made by special glands
    • the visceral mass is behind the mantle and hast most of the organs
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4
Q

how do mollusks feed

A
  • display all mode of feeding across the various species
  • slugs and snails have a radula, which is a straw like tongue covered in teeth that is supported by a cartilage rod, has various uses for feeding
  • Certain sea slugs and cephalopods use jaws to bite food
  • Some use poison or venom
  • some like clams and oysters use gills to filter feed
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5
Q

how do mollusks breath

A
  • Gill are used, sometimes within the mantle cavity
  • some have a cavity of folding tissue that is lined with blood vessels to absorb O2
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6
Q

how do mollusks respirate

A
  • Simple heart
  • An open circulatory system is used for the more sessile ones, which goes into sinuses which then lead back into vessels
  • Octopi and other motile taxa use closed circulatory systems
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7
Q

how do mollusks excrete waste

A
  • excrete solid waste through the anus
  • Nephridia eject ammonia from the body
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8
Q

how do mollusks respond to stimuli

A
  • vary from, small ganglia near the mouth combined with simple cords as well as touch receptors, statocysts (help balance), and ocelli
  • to very developed nervous systems in octopodes and their kin, developed brains and sense organs
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9
Q

how do mollusks reproduce

A
  • mostly separate sexes with external fertilization
  • in tentacled mollusks along with some snails, the sperm is injected into the female
  • some hermaphroditic snails exists, internal fertilization in both
  • some oysters can switch sexes
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10
Q

what are snails, slugs, and relatives

A
  • class Gastropoda
  • move with a big ventral foot
  • many have one piece shells on their dorsal side
  • various defense mechanisms: ink, hiding, shells, poison, nematocysts, bright colours
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11
Q

what are two shelled mollusks

A
  • Class Bivalvia
  • oysters, clams, scallops
  • free larva, sessile adults
  • some burrow while other stick to objects
  • scallops can flap to move
  • glands make shells and pearls
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12
Q

what are tentacled mollusks

A
  • Cephalopods
  • Octopi, Squid, Cuttlefish, nautiluses
  • have tentacles (8), + 2 arms, or 38-90 in nautilus
  • small internal shells, or no shells, except nautilus, squids have a flexible pen
  • fast movement
  • siphons move water
  • ink and colour changing
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13
Q

how do mollusks fit into our world

A
  • predators and prey
  • detritus feeders
  • hosts to various parasites
  • bivalves help monitor water
  • research on cancer medication
  • slugs + snails destroy plants
  • shipworms destroy wood
  • eating bivalves can poison you through red tide
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14
Q

what are annelids

A
  • phylum Annelida
  • Round, wormlike, with long segmented bodies
  • range a lot
  • 9000+ species
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15
Q

how are annelids segmented

A
  • septa or septum separate the segments
  • most segments are the same, though some are different
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16
Q

how do annelids feed

A
  • digestive tract or gut leads from mouth to anus
  • various structures
  • a pharynx holding jaws is common (held in mouth)
  • some pharynxes are sticky, have various functions
  • can filter feed with a mucus bag, or feather like fans
17
Q

how do annelids breath

A
  • gills
  • can also absorb through skin
  • skin must stay moist
18
Q

how do annelids do internal respiration

A
  • closed circulatory system
  • 2 blood vessels travel the length of the body
  • ring vessels move between side and go to organs
  • a few ring vessels near the anterior region contract in a simple heart like function
19
Q

how do annelids excrete waste

A
  • anus for solid
  • tubes called nephridia eject others
20
Q

how do annelids do response

A
  • pretty developed
  • brain, 2 nerve, 2 ganglia
  • a ventral nerve cord travels the length
  • sensory tentacles, statocysts, chem receptors and eyes
  • eyes vary from sports to full eyes
  • others have simplified sensors, ex earth worms
21
Q

how do annelids defend themselves

A
  • burrow for defense, some make CaCO3 tubes
  • some have jaws or spines for defense
22
Q

two do annelids move

A
  • longitudinal muscles contract the body
  • other wrap around and make it skinnier
23
Q

how do annelids reproduce

A
  • mostly sexual
  • vary, separate sexes or hermaphrodites, internal or sexual
24
Q

what are sandworms, bloodworms, and relatives

A
  • class Polychaeta (many bristles)
  • Many aquatic species
  • have paired paddle like appendages with bristles
  • burrow, hide, swim, or make tubes
25
Q

what are earth worms and their relatives

A
  • class Oligochaeta
  • Live in soil or water
  • less bristles
26
Q

what are leeches

A
  • class Hirudinea
  • Live in tropics, mostly freshwater
  • most are less than 6 cm, some 30cm or more
  • external parasites that drink blood, some carnivores
  • powerful suckers on both ends
  • muscular proboscus punctures flesh, pharynx sucks blood
  • some produce anesthetics
27
Q

how do leeches fit into our world

A
  • plankton host many larva
  • diets of many organisms
  • condition soil, aerate
  • decomposers