(Summary by Robert Higgins for University of Florida, Zoology 6027, Spring 1982)
Beware: Scanned document.
A. Echinoderes discovered in 1841 (Dujardin), considered to be allied to arthropods or annelids, later to nematodes.
C. Monograph by Zelinka (1920).
B. Kinorhynch characters: marine, unciliated, superficially segmented, more or less spinous, wormlike, with a retractile head, and 1 pair of protonephridia.
A. Size less than 1 nun.
B. Bottle-shaped and flattened ventrally. Head, neck, trunk.
D. No external ciliation. Cuticle divided into articulated segments or zonites. The spherical head forms the first zonite, the neck another zonite, the trunk 11 (12) zonites. Each segment has a dorsal and 2-3 ventral plates. The former bears median and lateral spines.(scalids).
F. One or more pair(s) of adhesive tubes, with large gland cells at the base, are on the ventral surface of third and fourth zonite.
A. Body, wall: columnar, syncitial epithelium extending into spines, and forming thickenings or chords longitudinally.
C. Body cavity: well-developed pseudocoel, containing amoeboid cells that originate from the wall of the digestive tract.
1. Mouth anterior with protrusible cone, surrounded by scalids
and armed with oral styles.
2. Pharynx: lined with cuticle and surrounded by muscle.
3. Esophagus with two pairs of salivary glands, and two
4. Stomach-intestine: nonciliated columnar epithelium.
5. Hindgut and terminal anus. Sphincter before hindgut and anus.
G. Nervous system closely associated with epidermis:
2. A midventral nerve cord, with one ganglion per segment. Other ganglia are not connected to form a cord.
1. Dioecious, but little sexual dimorphism (size, minor external details).
3. Males have 1 pair of testes and one pair of gonopores similarly located, plus 2-3 penial spicules.
B. 3-6 eggs, developing externally.
A. Marine, benthic.
B. Burrow in mud of coastal waters but some were found at 5000m depth.
D. Worm-like movements with the aid of scalids or by contractions of the head.
Conchorhagae: the third zonite forms the closing apparatus, i.e. a pair of shells. One genus: Semnoderes.
B. They bear similarities to sipunculids, acanthocephala, rotifers, tardigrades, nematodes. Gastrotrichs, kinorhynchs, and nematodes are considered as offshoots from a comnon stem.
Barnes R., 1974 : Invertebrate zoology, 3rd ed. Saunders, Philadelphia. pp 208-210.
Gosner K.L., 1971 : Guide to the identification of marine and estuarine invertebrates. Cape Hatteras to the Bay of Fundy. Wiley and Sons, NY. pp 195-197.
Hyman L., 1951 : The invertebrates. Vol. III. McGraw-Hill, NY. pp 53-59, pp 170-183.
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