Hydrozoa
Scientific classification
Kingdom: Animalia Subkingdom: Metazoa Phylum: Cnidaria Class: Hydrozoa Owen, 1843
Orders
Actinulida Capitata Chondrophora Filifera Hydroida Siphonophora Trachylina Picture of colonial hydrozoa which I took with a digital camera mounted on a Zeiss stereomicroscope This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... Scientific classification or biological classification is how biologists group and categorize extinct and living species of organisms. ... Phyla Porifera (sponges) Ctenophora (comb jellies) Cnidaria Placozoa Subregnum Bilateria  Acoelomorpha  Orthonectida  Rhombozoa  Myxozoa  Superphylum Deuterostomia     Chordata (vertebrates, etc. ... Phyla Radiata Cnidaria Ctenophora - Comb jellies Bilateria Protostomia Acoelomorpha Platyhelminthes - Flatworms Nemertina - Ribbon worms Gastrotricha Gnathostomulida - Jawed worms Micrognathozoa Rotifera - Rotifers Acanthocephala Priapulida Kinorhyncha Loricifera Entoprocta Nematoda - Roundworms Nematomorpha - Horsehair worms Cycliophora Mollusca - Mollusks Sipuncula - Peanut worms Annelida - Segmented worms Tardigrada - Water bears Onychophora - Velvet worms Arthropoda - Insects, etc. ... Classes Anthozoa - Corals and sea anemones Cubozoa - Sea wasps or box jellyfish Hydrozoa - Hydroids, hydra-like animals Scyphozoa - Jellyfish Cnidaria (from New Latin cnida nematocyst, fr. ... Sir Richard Owen and Dinornis bird skeleton Sir Richard Owen (July 20, 1804 - December 18, 1892) was an English biologist, comparative anatomist and palaeontologist. ... Scientific classification or biological classification refers to how biologists group and categorize extinct and living species of organisms. ... Genera Porpita Velella Chondrophores are an order of hydrozoans, gelatinous Cnidarians superficially resembling jellyfish. ... Siphonophora is an order of the Hydrozoa, a class of marine invertebrates belonging to the phylum Cnidaria. ...

Organisms that are in Class Hydrozoa come from the Phylum Cnidaria. Most specieas of Hydrozoa are marine and colonial and their life cycle includes both the asexual polyp and the sexual medusa stages. Medusas have a well-developed muscular velum that helps them move through water. Their exoskeleton is made of chitin or sometimes of calcium carbonate. Scientific classification or biological classification refers to how biologists group and categorize extinct and living species of organisms. ... Phylum is one of the levels of scientific classification of organisms; see the Phylum (biology) article. ... Classes Anthozoa - Corals and sea anemones Cubozoa - Sea wasps or box jellyfish Hydrozoa - Hydroids, hydra-like animals Scyphozoa - Jellyfish Cnidaria (from New Latin cnida nematocyst, fr. ... For the French ship of the line, see Océan Ocean (from Okeanos, a Greek god of sea and water; Greek ωκεανός) covers almost three quarters (71%) of the surface of the Earth. ... A life cycle includes the major sexual stages of a species, especially in regard to its ploidy. ... In zoology, a polyp is one of two forms of individuals found in many species of cnidarians. ... In biology, a medusa (also known as a hydromedusa) is a form of cnidarian in which the body is shortened on its principal axis and broadened, sometimes greatly, in contrast with the hydroid or polyp. ... In biology, chitin is one of the main components in the cell walls of fungi, the exoskeletons of insects and other arthropods, and in some other animals. ... Calcium carbonate is a chemical compound, with chemical formula CaCO3. ...

The freshwater hydrozoans are called Hydras and are solitary and do not have a medusa stage nor do they have any form of exo-skeleton. Hydras live in still and slow moving waters attached to leaves and stems. They have pedal discs composed of gland cells that help them to attach to substrates. Hydras use nematocysts in their tentacles to stun their prey with poison. The tentacles then lead the prey to the opening mouth. Hydras eat small crustaceans, insect larvae, and annelid worms. During asexual reproduction, buds leave the body wall and develop into young hydras. In sexual reproduction, eggs mature one at a time and are fertilized by sperm in the water. Cnidocytes are prey-capture and defensive cells found on animals of the phylum Cnidaria. ... The skull and crossbones symbol traditionally used to label a poisonous substance. ... Classes Branchiopoda Cephalocarida Malacostraca Maxillopoda Ostracoda Remipedia The crustaceans (Crustacea) are a large group of arthropods (55,000 species), usually treated as a subphylum. ... A database query syntax error has occurred. ... A larva (Latin; plural larvae) is a juvenile form of animal with indirect development, undergoing metamorphosis (for example, insects or amphibians). ... Classes and subclasses Class Polychaeta (paraphyletic?) Class Clitellata    Oligochaeta - Earthworms and others    Acanthobdellida    Branchiobdellida    Hirudinea - Leeches Class Myzostomida Class Archiannelida (polyphyletic) Class Echiura *Some authors consider the subclasses under Clitellata to be classes The annelids, collectively called Annelida (from Latin annellus little ring), are a large phylum of animals, comprising... Asexual reproduction is a form of reproduction involving only one parent. ... Schematic diagram of a sperm cell, showing the (1) acrosome, (2) cell membrane, (3) nucleus, (4) mitochondria, and (5) flagellum (tail) A sperm cell, or spermatozoon ( spermatozoa) (in Greek: sperma = seeds and zoon = living being), is the male haploid gamete. ...

Colonial hydrozoans have both a medusa stage and a polyp stage in their life cycle. They have a base, a stalk, and one or more polyps. Most polyps are feeding polyps called hydranths. They prey on tiny crustaceans, worms, and larvae. In reproduction, new polyps can either be feeding polyps or reproductive polyps known as gonangia. When a gonangia buds, a medusae is produced. These medusae will then mature and produce gametes. Zygotes become free-swimming planula larvae that settle on a suitable substrate, allowing them to develop into a hydroid colony by asexual reproduction. A zygote (Greek: ζυγωτόν) is a cell that is the result of fertilization. ... A planula is the free-swimming, flattened, ciliated, bilaterally symmetrical larva of a hydrozoan cnidarian. ...

Some examples of hydrozoans are: Hydra, Obelia, Portuguese man o' war (Physalia), Chondrophores, and Tubularia. Species Obelia dichotoma Obelia geniculata Obelia longissima Obelia bidentata Hydroids (genus Obelia) are from the class Hydrozoa, which consists of mainly marine and some freshwater species and have both the polyp and medusa stages in their life cycle. ... Binomial name Physalia physalis (Linnaeus, 1758) The Portuguese man o war (genus Physalia), also known as the blue bottle, is commonly thought of as a jellyfish but is actually a siphonophore—a colony of four sorts of polyps. ... Genera Porpita Velella Chondrophores are an order of hydrozoans, gelatinous Cnidarians superficially resembling jellyfish. ...