BIO 385 Invertebrate Zoology
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Invertebrate Diversity
Clade Gnathifera:
Rotifers & Acanthocephalans

(Click on any image for larger version)

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
  • Without Acanthocephalans, the group is paraphyletic
  • Clade that includes rotifers and acanthocephalans sometimes called Syndermata
Philodina
Fresh-water Rotifer, Philodina sp.; 100x
See also labeled photo.
Adineta
Fresh-water Rotifer, Adineta sp.
Squatinella
Fresh-water Rotifer, Squatinella sp.; collected Toleson, AZ
Monostyla
Fresh-water Rotifer, Monostyla sp.?; 100x
Euchlanis
Fresh-water Rotifer, Euchlanis sp.; 200x
Keratella
Fresh-water Rotifer, Keratella sp.; Phoenix, AZ
Brachionus
Fresh-water Rotifer, Brachionus sp.; Rio Salado, AZ; 200x
Synchaeta
Fresh-water Rotifer, Synchaeta sp.; Tolleson, AZ; 200x
Polyarthra
Fresh-water Rotifer, Polyarthra sp.; Rio Salado, AZ; 200x

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
  • Derived from within rotifer group
  • Formerly considered a separate phylum, but may be a Class of rotifers

Acanthocephalan
Acanthocephalan, stained whole mount

NeoechinorhynchusAcanthocephalan
Spiny-headed worm, Neoechinorhynchus sp., preserved specimen
This page last updated 1 August 2016 by Udo M. Savalli ()
Images and text Udo M. Savalli. All rights reserved.