hypostome

English

Etymology

From hypo- +‎ -stome.

Noun

hypostome (plural hypostomes)

1. (anatomy) Any of certain mouth appendages of some insects, arachnids, crustaceans, and hydrozoa; in particular:
   1. The ventral mouthpart plate in trilobites;
   2. The barbed attachment structure associated with the mouthparts of parasitic arachnids (e.g. ticks);
   3. The oral tip surrounded by tentacles in hydrozoan cnidarians.
   • 1953, H. B. Whittington, W. R. Evitt, Memoir 59: Silicified Middle Ordovician Trilobites, Geological Society of America, page 20,

     This mode of attachment and support of the hypostome in proparian trilobites is also shown by Öpik's work (1938, and references) and by Whittington (1941b, p. 514-517) and Evitt and Whittington (1953).

   • 2012, Georgia E. Lesh-Laurie, Chapter 5. Expression and Maintenance of Organismic Polarity, Allison L. Burnett (editor), Biology of Hydra, Harcourt Brace Jovanovich (Academic Press), pages 160-161,

     As a result or these interactions, the presence of a hypostome inhibits the formation of another hypostome nearby. Removal of the hypostome causes the level of inhibition to fall; regeneration of it restores this level (Webster, 1966).

   • 2020, Fatma El-Bawab, Invertebrate Embryology and Reproduction, Elsevier (Academic Press), page 251,

     The polyps of the two observed populations of Alatina cf. moseri showed no distinct differences. […] The body of the polyp is divided into three parts: the hypostome, the calyx and a stalk region. The latter includes a basal disc and a tiny periderm beaker enveloping the pedal region. The hypostome of polyps of both populations was four-lipped (Fig. 5.33F and G), balloon-shaped and ~14%–15% of the total body length (TBL). It was not completely contractible into the body.

   • 2022, Alan Gunn, Sarah J. Pitt, Parasitology: An Integrated Approach, 2nd edition, Wiley, page 191,

     Figure 7.4 Argas persicus^{[fowl tick]} […] (b) Hypostome of larval stage. The toothed hypostome is easily visible in the larval stage.

Synonyms

• hypostoma

Derived terms

• hypostomal
• hypostomial

Translations

appendage

• Irish: hipeastóm m

Anagrams

• homotypes, phytosome