Phylum Rotifera — Wheel Animals
Characteristics
- Very small, most <1 mm.
- Varied, complex shapes
- Anterior end has paired coronas lined with cilia
- Many forms are sessile, attach via posterior foot
- Mostly fresh water; a few are parasitic
- Most are parthenogenic
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Fresh-water Rotifer, Philodina sp.; 100x
See also labeled photo.
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Fresh-water Rotifer, Adineta sp.
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Fresh-water Rotifer, Monostyla sp.?; 100x
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Fresh-water Rotifer, Euchlanis sp.; 200x
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Fresh-water Rotifer, Keratella sp.; Phoenix, AZ
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Fresh-water Rotifer, Brachionus sp.; Rio Salado, AZ; 200x
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Fresh-water Rotifer, Synchaeta sp.; Tolleson, AZ; 200x
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Fresh-water Rotifer, Polyarthra sp.; Rio Salado, AZ; 200x
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Phylum Acanthocephala — Spiny-headed Worms
Characteristics
- Body cylindrical, usually with rings of small spines
- Fluid-filled proboscis with hooks and spines
- Lack gut; reduction of most organs
- Pseudocoelom filled with large gonads
- Intestinal parasites of vertebrates
- Likely related to rotifers
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Acanthocephalan, stained whole mount
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Spiny-headed worm, Neoechinorhynchus sp., preserved specimen
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Phylum Gastrotricha
Characteristics
- Minute (<1 mm) unsegmented animals
- Body moderately elongated, somewhat flattened
- Rounded head with slight neck constriction
- Sensory bristles on head
- Posterior end with pair of projections (caudal furca)
- Epidermis with plates or spines
- Cilia on ventral surface
- In fresh water and marine sediments
- Phylogenetic relationships uncertain
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Gastrotrich, Chaetonotus sp.
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[Phylum Entoprocta (Kamptozoa)]
Characteristics
- Solitary or colonial, often stalked
- Tiny size (usually <2 mm)
- Ring of ciliated tentacles surround mouth and anus
- U-shaped gut
- This phylum is not represented in lab
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Nodding Head Entoproct, possibly Barentsia sp.; CA
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