DIVERSITY OF LIFE

THE RADIATA (LINNAEUS 1758)

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Radiata (ray-dee-AH-tuh) is derived from a participle of the Latin word Radio meaning beaming or shining.  The reference is to the sun-like or starburst pattern of radial symmetry.

 

INTRODUCTION TO THE RADIATA

Almost certainly Radiata is an artificial grouping of unrelated taxa that have the common features of radial symmetry and tissues that arise from two cell layers (diploblastic).  The tissues are arranged into organs.  Almost all are marine.  Some radiates go through an alternation of a sessile vegetative stage (the hydroid) and a motile sexual stage (the medusoid).  Many produce free-swimming larval forms.  Because the Radiates resemble large free-living gastrulas, the shared trait of diploblasty likely is primitive.  Thus, they are grouped together on the basis of a shared primitive trait and therefore paraphyletic.  Please consult The Major Clades of the Animal Kingdom for some views on the relationships of the radiate phyla with each other and with the other phyla of the animal kingdom.

We have included the Myxozoa within the Radiata because it is most certainly a highly reduced Cnidarian.  Traditionally, it has been considered a "protozoan" and before the demise of the taxon, Protozoa, was a member of the Sporozoa.  Their particular relationship with other animal groups is still under dispute.  However, what we interpret as clear affinities with the Cnidaria have prompted us to include the Myxozoa as a separate phylum in the Radiata.

 

PHYLUM CNIDARIA

CLASS HYDROZOA (5 ORDERS)

Bouganvilla, Calycopsis, Eleutheria, Eudendrium, Hydra, Hydractina, Hydrocoryne, Janaria, Lar, Pennaria, Polyorchis, Sarsia, Staurocladia, Stylactis,Tubularia, Abietinaria, Aequoria, Aglaophenia, Bonneviella, Campanularia, Cuvieria, Obelia, Gonionemus, Gonothyrea, Lovenella, Plumularia, Sertularia, Aegina, Botrynema, Craspedacusta, Cunina, Hydroctena, Liriope, Polypodium, Rhopalonema, Solmissus, Agalma, Apolemia, Eudoxoides, Nectocarmen, Physalia, Rhyzophysa, Sphaeronectes, Porpita, Velella, Halammohydra, Otohydra.

CLASS SCYPHOZOA (4 ORDERS)

Aurelia, Cyanea, Haliclystus, Lucernaria, Atolla, Linuche, Naustihoe, Periphylla, Stephanoscyphus, Tetraplatia, Chrysaora, Pelagia, Sanderia, Stygiomedusa, Cassiopeia, Cephea, Eupilema, Mastigias, Rhizostoma, Stomolophus.

CLASS CUBOZOA (1 ORDER)

Tripedalia, Carybdea, Chironex, Tamoya.

CLASS ANTHOZOA

SUBCLASS CERIANIPATHARIA (2 ORDERS)

Cerianthus, Antipathes, Arachnanthus, Botruanthus, Ceriantheomorphe, Ceriantheopsis, Pachycerianthus.

SUBCLASS OCTOCORALLIA (=ALCYONARIA; 8 ORDERS)

Alcyonium, Anthomastus, Ceratocaulon, Gersemia, Parerythropodium, Pseudogorgia, Acanthogorgia, Biareum, Corallium, Eugorgia, Eunicella, Isis, Leptogorgia, Muricea, Parisis, Psamogorgia, Swiftia, Epiphaxum, Heliopora, Anthoptilum, Balticina, Cavernularia, Funicularia, Ptilosarcus, Stylatula, Umbellula, Virgularia, Haimea, Hartea, Monoxenia, Psuchastes, Taiaroa, Clavularia, Cornularia, Sarcodictyon, Tubipora, Gorgonia, Renilla, Pennatula, Coelogorgia, Paratelesto, Telesto, Telestula.

SUBCLASS HEXACORALLIA (=ZOANTHARIA; 4 ORDERS)

Adamsia, Aiptasia, Alicia, Anthopleura, Anthothoe, Bartholomea, Bunodactis, Calliactus, Condylanthus, Diadumene, Edwardsia, Epiactus, Halcampa, Haliplanella, Heteractis (Radianthus), Liponema, Metridium, Peachia, Phyllodiscus, Ptychodactis, Stichodactyla, Stomphia, Triactis, Agaricia, Astrangia, Balanophyllia, Dendrogyra, Flabellum, Actinia, Fungia, Goniopora, Letepsammia, Meandrina, Montipora, Oculina, Pachyseris, Porites, Psammocora, Siderastraea, Stylophora, Epizoanthus, Isaurus, Isozoanthus, Palythoa, Parazoanthus, Thoracactus, Zoanthus, Amplexidiscus, Corynactis, Rhodactis, Ricordea.

 

PHYLUM MYXOZOA

CLASS MYXOSPOREA (2 ORDERS)

Myxosoma, Myxobolus, Coccomyxa, Myxidium, Sphaerospora, Myxobilatus, Ceratomyxa, Kudoa, Trilospora.

CLASS ACTINOSPOREA (1 ORDER)

Triactinomyxon, Tetractinomyxon, Sphaeractinomyxon.

 

PHYLUM CTENOPHORA

CLASS TENTACULATA (6 ORDERS)

Cestum, Velamen, Aulococtena, Bathyctena, Callianira, Dryodora, Euplokamis, Hormiphora, Lampea, Mertensia, Pleurobrachia, Tinerfe, Ganesha, Bolinopsis, Deiopea, Leucothea, Mnemiopsis, Ocyropsis, Coeloplana, Ctenoplana, Lyrocteis, Savangia, Tjalfiella.

CLASS NUDA (1 ORDER)

Beroe, Neis.

 
Linnaeus, C. 1758. Systema Naturae per Regna Tria Naturae. Regnum Animale. Laurentii Salvii. Stockholm.  

By Jack R. Holt and Carlos A. Iudica.  Last revised: 08/29/2016