BIO 385 — Invertebrate Zoology
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Invertebrate Diversity
Nematodes & Related Worms

(Click on any image for larger version)

Phylum Nematoda — Roundworms

Characteristics

  • Body elongate, round in cross section, tapered at ends
  • Unsegmented
  • Complete gut
  • Pseudocoelomate or acoelomate
  • Widespread and abundant in all habitats; some parasitic
Vinegar Eel
Vinegar Eel, Turbatrix aceti, a free-living nematode.
Marine Nematodes
Free-living marine nematodes
Dog Hookworm
Dog Hookworm, Ancylostoma caninum, female (stained whole mount)
Ascaris C.S.
Ascaris lumbricoides; stained cross-sections of female, male, and through pharynx.
See also labeled photo.
Trichina worm
Adult female trichina worm, Trichinella spiralis (stained whole mount)
Trichinella
Encysted larva of trichina worm, Trichinella spiralis, in muscle tissue (Trichinosis); (stained whole mount).
Whipworm
Whipworm, Trichuris sp., an intestinal parasite; (stained whole mount).

Unidentified marine nematode on a microscope slide placed in a salt-water aquarium (bright field, 10x objective lens)

Phylum Nematomorpha — Horsehair Worms

Characteristics

  • Body greatly elongate, thread-like (up to 1 m long), often curled up and folded on itself
  • Unsegmented
  • Lack functional gut
  • Pseudocoelomate
  • Adults mostly in fresh water; larvae parasitic on insects
Horsehair Worm
Horsehair Worm, Paragordius sp.?, KY
Gordian Worm
Horsehair worm emerging from its cricket host; preserved specimen

Phylum Priapulida — Penis Worms

Characteristics

  • Fully retractable introvert that is covered in spines
  • Chitinous cuticle that is molted
  • Posterior end has branching caudal appendage, presumably for respiration
  • Small, up to 20 cm long
  • Benthic marine
See additional fossil worms here: scroll down for a priapulid worm
Priapulus
Dried penis worm, Priapulus sp.
Ottoia Model
Model of penis worm, Ottoia sp.; Cambrian Period
Palaeoscolex fossil
Fossil of Palaeoscolex sp., a probable stem-priapulid; Cambrian Period, China
This page last updated 23 December 2020 by Udo M. Savalli ()
Images and text © Udo M. Savalli. All rights reserved.