Hydroids

Taxobox
name = Hydroida


image_width = 220px
regnum = Animalia
subregnum = Metazoa
phylum = Cnidaria
classis = Hydrozoa
ordo = Hydroida
ordo_authority =

ZOOLOGY: A hydroid in zoology is an animal that superficially appears plant-like. Hydroids are however carnivorous animals that feed on minute crustaceans. Hydroids are related to jellyfish, sea anemones and corals. Some species live a solitary existence, others live in colonies.

BOTANY: A hydroid in botany is a type of cell contained in many mosses. When it dies, it leaves a tiny channel which water can travel through. The hydroid may be the progenitor of the tracheid, the characteristic water-conducting cell of the tracheophytes. The hydroid lacks lignin (a waterproofing substance that also lends structural support) and the cell wall structure found in tracheids.

=External links=
* [http://www.afsc.noaa.gov/groundfish/HAPC/Hydroids_synopsis.htm/ NOAA page about hydroids] with a picture. Information compiled by the [http://www.afsc.noaa.gov/default.htm/ Alaska Fisheries Science Center] .
* [http://www.seaslugforum.net/factsheet.cfm?base=hydroids/ Sea Slug Forum] Pictures and descriptions of some hydroids.
* [http://www.vattenkikaren.gu.se/fakta/arter/cnidaria/hydrozoa/olikahe.html/ Pictues of shallow water hydroids] from Aquascope.