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15.2: Marine Animals in Benthic Environments - Invertebrates

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    Invertebrates are animals without backbones.
    Invertebrates inhabit pelagic, benthic, and terrestrial environments. The majority of animal species that inhabit benthic environments are invertebrates. These organisms feed on other benthic organism (plants and animals), pelagic organisms (small fish and plankton forms), and decaying matter. These animals are, in turn, eaten by a host of pelagic animals (secondary and tertiary tropic feeders).

    PHYLUMS Examples
    Protozoa Single-celled animals (microbes): single-celled zooplankton, ciliates, flagellates, amoebas
    Porifera Sponges – filter feeders
    Coelenterada Coral, Jellyfish, Anemones
    Annelida Worms
    Mollusca Bivalves, squid, octopus, nautilus, gastropods (things with shells or large cavities),
    (extinct varieties: cephalopods, belemnites, ammonites)
    Brachiopoda Have two valves, but valves are on top and bottom
    Arthropoda Crabs, shrimp, scorpions, and spiders (trilobites, eurypterids)
    Echinodermata Sea Stars, urchins and sea cucumbers (spiny skin)

    Geologic Time Scale summary
    Figure 15.2. Geologic Time Scale with summary of major events and appearance of plant and animal groups in the geologic record.

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