NAU Biology BIO 190 NAU
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BIO190: The Class: Pseudocoelomates: Lesson 16

The Pseudocoelomate Animals

Review fig 16-1

Characteristics of pseudocoelomate phyla (p. 303)

Phylum Rotifera

Visit these web sites for more information on Rotifera:
Rotifer Systematics Database

Rotifera derive their name from the characteristic ciliated crown, or corona, that, when bearing, often gives the impression of rotating wheels.

  • "wheel-animals"

  • external
    1. foot
      1. pedal glands

  • internal
    1. mastax
      1. trophi

    2. flame cells
    3. brain
    4. eyespots

  • reproduction
    1. dioecious
    2. parthenogenesis (fig. 16-4)
      1. diploid amictic eggs
      2. haploid mictic eggs

    Phylum Nematomorpha (fig. 16-18)

    The popular name for the Nematomorpha is "horsehair worms" based on an old superstition that the worms arise from horsehairs that happened to fall into the water, and they look something like hairs from a horse's tail.

    Phylum Acanthocephala (fig. 16-19 --> 16-20)

    The members of the phylum Acanthocephala are commonly known as spiny-headed worms.

    Phylum Entoprocta (fig. 16-21)

    Entoprocta is a small phylum of about 150 species of tiny, sessile animals.

    See phylogeny/Adaptive Radiation (pg. 317)

    Once you have completed the lesson, you should go to Assignment 16-1.

    E-mail Sylvester Allred at


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