Crossword clues for hydroid
The Collaborative International Dictionary
Hydroid \Hy"droid\, a. [Hydra + -oid.] (Zo["o]l.) Related to, or resembling, the hydra; of or pertaining to the Hydroidea. -- n. One of the Hydroideas.
Wiktionary
a. Of or pertaining to such creatures n. Any of many colonial coelenterates that exist mainly as a polyp; a hydrozoan
WordNet
n. colonial coelenterates having the polyp phase dominant [syn: hydrozoan]
Wikipedia
A hydroid is a type of vascular cell that occurs in certain bryophytes. In some mosses such as members of the Polytrichaceae family, hydroids form the innermost layer of cells in the stem. At maturity they are long, colourless, thin walled cells of small diameter, containing water but no living protoplasm. Collectively, hydroids function as a conducting tissue, known as the hydrome, transporting water and minerals drawn from the soil. They are surrounded by bundles of living cells known as leptoids which carry sugars and other nutrients in solution. The hydroids are analogous to the tracheids of vascular plants but there is no lignin present in the cell walls to provide structural support.
Hydroids have been found in some fossilised plants from the Rhynie chert, including Aglaophyton, where they were initially mistaken for xylem vessels.
Hydroids are a life stage for most animals of the class Hydrozoa, small predators related to jellyfish. Some hydroids such as the freshwater Hydra are solitary, with the polyp attached directly to the substrate. When these produce buds, they become detached and grow on as new individuals.
The majority of hydroids are colonial. The original polyp is anchored to a solid substrate and forms a bud which remains attached to its parent. This in turn buds and in this way a stem is formed. The arrangement of polyps and the branching of the stem is characteristic of the species.
Some species have the polyps budding directly off the stolon which roots the colony. The polyps are connected by epidermis which surrounds a gastrovascular cavity. The epidermis secretes a chitinous skeleton which supports the stem and in some hydroids, the skeleton extends into a cup shape surrounding the polyp.
Most of the polyps are gastrozooids or feeding polyps, but some are specialised reproductive structures known as gonozooids. In some species, further specialised zooids are formed.
Hydroid may refer to:
- Hydroid (zoology)
- Hydroid (botany)
Usage examples of "hydroid".
It was a hydroid, a development of that strange animal-vegetable that, sometimes almost microscopic, waves in the sea depths like a cluster of flowers paralyzing its prey with the mysterious force that dwells in its blossom heads!
Haast supposes, be a ground feeder, existing on the smaller hydroid zoophytes, otherwise it must, I think, turn on its side in seizing its prey.
Haast supposes, be a ground feeder, existing on the smaller hydroid zoophytes, otherwise it must, I think, turn on its side in seizing its prey.