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Related to, or resembling, the hydra; of or pertaining to the Hydroidea. -- n.

An extensive order of Hydrozoa or Acalephæ. [Written also Hydroida.]

A group of Coelenterata, including the Medusæ or jellyfishes, and hydroids; -- so called from the stinging power they possess. Sometimes called sea nettles.

A kind of embryo of certain hydroids (Tubularia), having a stellate form.

Applied to sexual zooids of hydroids, that have a saclike form and do not become free; -- opposed to phanerocodonic.

nimals resembling a flower, as any species of actinia or sea anemone, and other Anthozoa, hydroids, starfishes, etc. -- Animal heat (Physiol.), the heat generated in the body of a living animal, by means of which the animal is kept at nearly a uniform temperature. -- Animal spirits. See under Spirit. -- Animal kingd…

A division of Hydroidea in which the zooids are naked, or not inclosed in a capsule. See Tubularian.

In certain hydroids, an imperfect zooid, whose special function is to produce medusoid buds. See Hydroidea, and Athecata.

aining attached to the parent stalk or cell, at other times becoming free; gemmation. See Hydroidea.

h is formed by a polyp. (b) One of the cuplike structures inclosing the zooids of certain hydroids. See Campanularian. [Written also calycle. See Calycle.]

A hydroid of the family ampanularidæ, characterized by having the polyps or zooids inclosed in bell-shaped calicles or hydrothecæ.

The common soft tissue which unites the polyps of a compound hydroid. See Hydroidea.

The hydroid or naked-eyed medusæ. See Hydroidea.

mach; -- applied to a mode of budding from the interior of the gastric cavity, in certain hydroids.

Animals which increase by budding, as hydroids.

A reproductive bud of a hydroid; a simple gonophore.

A sexual zooid produced as a medusoid bud upon a hydroid, sometimes becoming a free hydromedusa, sometimes remaining attached. See Hydroidea, and Illusts. of Athecata, Campanularian, and Gonosome.

The reproductive zooids of a hydroid colony, collectively.

A capsule developed on certain hydroids (Thecaphora), inclosing the blastostyle upon which the medusoid buds or gonophores are developed; -- called also gonangium, and teleophore. See Hydroidea, and Illust. of Campanularian.

A sexual zooid, or medusoid bud of a hydroid; a gonophore. See Hydroidea, and Illust. of Campanularian.