Chapter 7 - Animals Without Backbones

Notes for Chapter 7:
Invertebrate Animals in the Sea

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Case History: Sherlock Holmes and the Most
Dangerous Marine Animal

RQ 7.1: In the Sherlock Holmes story, The Lion's Mane,
who was the culprit and what were the tell-tale signs?

    Featured Organisms (p. 153-154):
        Irukandji stinger (a tiny cubomedusa, Carukia barnesi)
        The sea wasp (a larger cubomedusa, Chironex fleckeri)

I. The Animal Family Tree
    Note: It is recommended that you skip this section entirely.
    It is worse than old fashioned; it is grossly misleading.
    Especially bad is Figure 7.1, which is perhaps the most
    "unparsimonious" diagrams of animal evolution I have ever
    seen. Instead, view these diagrams for a comparison of
    older views of animal relationships with a more up-to-date
    tree of animal relationships based on DNA sequence.
    For an overview of the early fossil record of animals through
    time click here, or see this article for a more detailed
    overview including recent fossil and developmental
    discoveries.

II. Sponges (Phylum Porifera) More Links
terms: osculum, spicules

RQ 7.2: Why could it be said that sponges are important
to all the water overhead (that is, if they had a head)?

Visit Source of this
Animated Moon Jelly

III. Jellyfish, Sea Anemones, Corals, and Ctenophores
       (Phyla Cnidaria and Ctenophora)
        terms:
    a) Cnidarians - More Links
        terms: polyp, medusa, colonies, nematocysts (or here)

RQ 7.3: Explain how the polyp and medusa are different parts
of a hydrozoan's life cycle?

RQ 7.4: What are nematocysts and how are they used by cnidarians?

RQ 7.5: Contrast a coral and a siphonophore as two kinds of
cnidarians that live as colonies.

Featured organisms (p. 108, Fig. 5.1, p. 158, Fig. 7.5):
Siphonophores (colonial jellyfishes)

b) Ctenophores - More Links
terms: combs, colloblasts

IV. The Larger Worms (Phyla Annelida, Hemichordata,
Echiura, Sipuncula, Nemertea, and Pogonophora)
terms: deposit feeders, suspension feeders

RQ 7.6: Contrast deposit and suspension feeding by what the
diet consists of in each case.

V. Smaller Worms and Parasites (Phyla Nematoda,
     Platyhelminthes, Priapulida, Chaetognath, Acanthocephala,
     Nematomorpha, and Mesozoa)
        terms:

VI. Squids, Snails, Bivalves, and Chitons (Phylum Mollusca)
terms: radula, ctenidium (gill), foot, mantle (secretes shell),
mantle cavity (where gills are)

    a) Snails and Their Relatives (Class Gastropoda)
        terms: trochophore and veliger larval stages, velum,
            protoconch (larval shell)

   RQ 7.7: How does a veliger larva of a collect food differently
        than it will when it later metamorphoses into a juvenile creeping
        snail, for example on a rocky shore.

1) Prosobranch snails are grazers, predators, suspension feeders.

   RQ 7.8: Give three contrasting examples of how adult gastropods
        (including snails) can have extremely different means of
        collecting food.

2) Opisthobranchs (sea slugs including nudibranchs) are
few in species, diverse in life-styles.

    Featured Pelagic Molluscs (p. 165-166):
     floating purple snail (Janthina janthina)
     heteropods (planktonic swimming snails)
     pteropods (planktonic opisthobranchs)
     blue dragon "solar powered" sea slug (Pteraeolidia janthina)

RQ 7.9: Explain how a sea slug manages to be "solar powered."

    b) Clams, Oysters, Mussels, Scallops and Their Relatives
        (Class Bivalvia)
        terms: siphon

RQ 7.10: How does a clam use its siphon?

    c) Octopuses, Squids, Cuttlefish, and Nautiluses
        (Class Cephalopoda)
        terms: pen

         Featured organisms (p. 108, Fig. 5.1, p. 167, Fig. 7.13c):
     Chambered nautilus (Nautilus) -
            More Links: 1 - 2 - 3 - 4 - 5 - 6
     Cuttlefish (Sepia)
     Giant squid (Architeuthis dux, Box 7.1, Fig. 7.15) -
            More Links: 1 - 2
     Giant Pacific octopus (Octopus dofleini, Fig. 7.13b)

   RQ 7.11: What is evidence that an octopus is "smart"
        at least relative to other animals without backbones?
        What is the evidence that there are limits to this
        intelligence?

    d) Chitons, Tusk Shells, Monoplacophorans, and Solenogastors
        (Classes Polyplacophora, Scaphopoda, Monoplacophora, and
     Aplacophora)
     Prof. Eernisse works on Chitons!
     Here is his compilation of Web Images
            (More links: 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10 - 11)

RQ 7.12: What features are the same in all chitons but
different from other molluscs?

VII. Bryozoans (or Ectoprocts), Brachiopods, Phoronids, and
Entoprocts (Imposters of Four Phyla)
terms: lophophore

VIII. The Animal Underworld (Phyla Gnathostomulida, Gastrotricha,
Kinorhyncha, Rotifera, Loricifera, Tardigrada, and Placozoa)
terms: interstitial animals

RQ 7.13: Characterize where interstitial animals live.

IX. Crabs, Shrimps, Lobsters, and Their Relatives (Phyla
Arthropoda and Onychophora)

    a) Features of Crustaceans
        terms: nauplius larva, exoskeleton, molting, copepodite, zoea,
            and megalops larval stages

b) The Diversity of Crustaceans
terms: carapace

        Featured Organism p. 67: Sand crabs (Emerita analoga)
        Featured Organism p. 68: Jonah crab (Cancer borealis)
        Featured Organism   p. 77, Fig. 3.12: ghost shrimp
        Featured Organism p. 15, p. 114, Tab. 5.1: Copepod
        Featured organism p. 120: crab, Cancer productus

1) Copepods are central to ocean food webs.

RQ 7.14: Why are copepods said to be central to ocean food webs?

        2) Life cycles reveal that all barnacles are crustaceans - and
            some parasites are barnacles.
        terms: hermaphroditic, nauplius to cypris larval stages

   RQ 7.15: A barnacle does not look much like other crustaceans
        (e.g., crabs, lobsters, and shrimps). What is the evidence that
        barnacles are crustaceans?

c) The Rest of Arthropods

d) The Only Nonmarine Phylum (Onychophora)

X. Sea Stars, Sea Urchins, Sea Cucumbers, and Their Relatives
(Phylum Echinodermata)More Links

a) Stars, Cukes, Urchins, and Brittle Stars Have Prominent
Feeding Roles

RQ 7.16: Why is a seastar said to have a prominent feeding role?
How about a sea urchin?

b) Crinoidsand Sea Daisies are Deep-Sea Surprises

XI. Sea Squirts, Salps, and Their Relatives (Phylum Chordata)

   RQ 7.17: Briefly characterize how something as squishy as
        a suspension feeding sea squirt can be considered to be a
       member of our own phylum, Chordata.

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