Animalia: Mollusks, Segmented Worms, and Arthropods Key

  1. PROTOSTOMES
    1. Write the term that matches the phrase.
      1. Embryonic opening forming mouth: blastopore
      2. Type of coelom: true
      3. Level of organization: organ system
      4. Body plan: tube-within-a-tube
      5. Type of symmetry: bilateral
      6. Embryonic tissues present: endoderm, ectoderm, mesoderm
  2. MOLLUSKS
    1. List the distinguishing characteristics of mollusks
      1. ventral muscular foot
      2. dorsal visceral mass
      3. mantle surrounds visceral mass, often secfretes shell
      4. radula - filelike mouthpart for scraping
    2. Matching
      1. Monoplacophorans 2. Chitons (Polyplacophora) 3. Snails and slugs (Gastropoda) 4. Tooth shells (Scaphopoda) 5. Clams and mussels (Bivalvia) 6. Octopi and squids (Cephalopoda)
        Octopi and squids (Cephalopoda)Image-forming eyes   Tooth shells (Scaphopoda)Conical shell open at each end
        All except clams and mussels (Bivalvia)Radula present   Chitons (Polyplacophora)Shell of 8 plates
        MonoplacophoransRemnants of segmentation   Clams and mussels (Bivalvia)Shell of 2 valves
        Octopi and squids (Cephalopoda)All predaceous   Clams and mussels (Bivalvia)Filter-feeders
        Tooth shells (Scaphopoda), Gastropoda(?)Digging foot   Snails and slugs (Gastropoda)Crawl on flattened foot
        Monoplacophorans, Chitons, Octopi and squidsMarine only   Octopi and squids (Cephalopoda)Foot modified into tentacles
    3. Draw a radula
      ?
    4. Match unknowns
      • Monoplacophorans: F
      • Chitons (Polyplacophora): E
      • Tooth shells (Scaphopoda): B
      • Snails and slugs (Gastropoda): D
      • Clams, oysters, and mussels (Bivalvia): A
      • Octopi and squids (Cephalopoda): C
    5. Clams
      1. Write the term that matches the phrase.
        1. Covers visceral mass and secretes shell: mantle
        2. Muscles closing valves of shell: abductor
        3. Brings water into mantle cavity: incurrent siphon
        4. Used to dig into mud or sand: digging (muscular) foot
        5. Organs of gas exchange: gills
      2. Describe the feeding process:
        Incurrent siphon -> mantle cavity, food trapped in mucus covering the gills, carried to labial palps and into mouth. Extracellular digestion in digestive tract, open corculatory system.
    6. Squid
      List the adaptations for a predaceous, swimming lifestyle.
       Foot modified into arms (tentacles). Horny beak to tear prey. Siphon aids swimming. Image-forming eyes. Closed c.s?
  3. ANNELIDS
    1. What is the primary distinguishing characteristics of annelids?
      segmented body
    2. Matching
      1. Oligochaetes (Oligochaeta) 2. Polychaetes (Polychaeta) 3. Leeches (Hirudinea)
        PolychaetesHead with simple eyes   LeechesBlood-sucking parasites
        OligochaetesFew setae   PolychaetesParapodia and many setae
        OligochaetesHermaphroditic   LeechesSuperficial rings on somites
        LeechesSuckers for attachment   PolychaetesMarine only
    3. Match unknowns
      • Polychaetes (Polychaeta): B
      • Oligochaetes (Oligochaeta): A
      • Leeches (Hirudinea): C
    4. Earthworms
      1. Write the term that matches the phrase.
        1. Membranes dividing segments: septa
        2. Secretes the egg case: clitellum
        3. Grinds food into small particles: gizzard
        4. Receives sperm during copulation: seminal receptacles
        5. Removes metabolic wastes: nephridia (metanephridia)
        6. Provides traction for movemnet: setae?
        7. Transports nutrients to body cells: blood
      2. Considering that the intestine digests food and absorbs nutrients into the blood, what is the typhlosole amd what is its value?
        dorsal part of intestine wall, folds inward and incerases surface area of intestinal lining
      3. As observed in your dissection:
        1. Draw dorsal view of ventral nerve cord:
          ?
        2. Does the crop or gizzard have a thicker wall? gizzard
          Relate this to the function of each: Crop stores food; Gizzard grinds
  4. ARTHROPODS
    1. List the major characteristics of arthropods:
      segmented body: cephalothorax or head and thorax and abdomen, jointed appendages, exoskeletonn of chitin, simple or compound eyes, open c. s.
    2. Matching
      1. Arachnids (Cheliceriformes) 2. Crustaceans (Crustacea) 3. Centipedes (Chilopoda) 4. Millipedes (Diplopoda) 5. Insects
        InsectsThree pairs of legs   CrustaceansCompound eyes
        CrustaceansTwo pairs of antennae   ArachnidsFour pairs of legs
        Arachnids, CrustaceansCephalothorax and abdomen   InsectsHead, thorax and abdomen
        CentipedesELongate flattened body   ArachnidsNo antennae
        MillipedesBody segments fused in pairs   InsectsCompound and simple eyes
        MillipedesELongate, dorsally convex body   CrustaceansFive pairs of legs
    3. List the stages in an insect's life cycle with:
      incomplete metamorphosis: egg, nymph grasshopper (naiad dragonfly does not resemble adult), adult
       complete metamorphosis: egg, larva, pupa, adult
    4. Considering the complete metamorphosis of a butterfly life cycle as an example, what is the adaptive advantage of
      1. The different feeding patterns of larvae and adult? Specialized niches/seasons
      2. The pupal stage? Survive unfavorable condicions
    5. Match unknowns
      • Arachnids (Cheliceriformes): D
      • Centipedes (Chilopoda): B
      • Insects: E
      • Crustaceans (Crustacea): A
      • Millipedes (Diplopoda): C
    6. Crayfish dissection
    7. Grasshopper dissection
  5. UNKNOWN STRUCTURES
    1. ?
Lab notes made Sep 05, 2007 by Peter Chen