(sea gooseberry ctenophore) |
BASAL METAZOA
modified from
|
(sea butterfly ctenophore) |
======================================== Porifera (sponges) | <<=M=====| ====P============================== Placozoa (placozoans, Trichoplax) | | ==1==| =============================================== TO CNIDARIA ===> ==E==| | =====C================== Ctenophora (comb-jellies) M= METAZOA ==2===| E= EUMETAZOA ======================== Bilateria (all higher animals)
Back to Zool 250 tree for animal phyla
TRAITS SUPPORTING EACH CLADE
(** plesiomorphic- a primitive state, not unique to clade):
b) dorso-ventral body axis c) true radial symmetry b) diploblastic** c) outer surfaces not true epithelia (no basal lamina) |
c) giant compound cilia form comb rows d) colloblast cells e) pair of elongate tentacles in tentacle sheaths f) biradial symmetry g) multiciliated cells* |
(Obelia polyps + medusa) |
(hydrozoan medusa) |
PHYLUM CNIDARIA
(= anemones, jellyfish, etc) (tree and traits from Ruppert et al. 2004) |
(anthozoan polyp) |
(scyphozoan medusa) |
==2============== Hydrozoa (hydroids, siphonophores, hydrocorals, etc.) | <<==1===| ==4========= Anthozoa$ (anemones, corals, gorgonians, etc.) ==3==| | ===6=== Cubozoa (sea wasps) ==5==| ===7=== Scyphozoa (jellyfish)
Back to Zool 250 tree for animal phyla
TRAITS SUPPORTING EACH CLADE (** plesiomorphic- a primitive state, not unique to clade):
b) nematocyst with operculum c) diploblastic** and radial symmetry** b) stenotele nematocyst c) simple bell margin in medusa, no rhopalia** d) simple gastrovascular cavity in polyp** e) medusa by simple budding f) medusa has simple manubrium g) cnidocytes strictly epidermal (gastrodermis lacks cnidocytes)** h) mesoglea lacks cells i) gonads epidermal b) gastrodermal cnidocytes in both polyp & medusa stage c) gastric filaments with cnidocytes d) gastrodermal gonads e) septate gastrovascular cavity in polyp f) true myocytes migrate to mesoglea |
b) nematocysts lack operculum c) tubular pharynx with siphonoglyph in polyp b) funnel-shaped polyp c) medusae produced by strobilation d) medusa with 4 septa and septal funnels e) 8 gonadal bands on septae f) rhopalia b) small polyps lack septae c) tentacles on pedalia at corners of bell d) 4 rhopalia with complex ocelli e) velarium (velum-like structure in medusae) f) highly venomous nematocysts b) large manubrium on medusae c) 8-fold notched bell margin with rhopalia |
$ Molecular data suggest Anthozoa are sister group to the Medusozoa (=Hydrozoa + Cubozoa + Scyphozoa, all of which have a unique, linear mtDNA molecule; Martindale et al. 2002 Molec Phylog Evol 24: 358) but some morphological data contradict this relationship (Collins et al. 2006 Sys Biol 55:97). Stay tuned!