(hexactinellid sponge) |
PHYLUM PORIFERA
(= sponges) (tree & traits from
|
(calcareous sponge) |
(demosponge) |
====== Calcarea## (calcareous sponges; includes ascon, sycon & leucon grades) ==2==| | ====== Homoscleromorpha (coralline sponges; leucon grade) <<===1==| | ==4=== Hexactinellida (glass sponges; no regular canal system) ==3==| ==5=== Demospongia (most living sponge species; leucon grade)
Back to Zool 250 tree for animal phyla
TRAITS SUPPORTING EACH CLADE (** plesiomorphic- a primitive state, not unique to clade):
b) water canal system with pumping choanocytes** (monociliated cells with diplosome) c) extensive mesenchyme (gelatinous proteinaceous matrix containing skeletal material and amoeboid cells) d) silica spicules, initiated intracellulary e) pinacoderm (epithelium-like outer layer) lacking basal lamina in some groups and intercellular junctions f) dynamic tissue remodelling (reversible differentiation of most cell types) b) porocytes (pore cells) |
b) most cells, including collar cells, are part of an extensive syncytium (multinucleate fabric of cells) b) distinctive 4-pointed spicule (tetraxon) c) porocytes (pore cells) |
## PARAPHYLETIC PORIFERA? (alternative molecular phylogeny from Sperling et al. 2009) (OPTIONAL, for information only)
==================== Ph CHOANOFLAGELLATA (collar flagellates; Protista) | | =========== Hexactinellida (glass sponges; no regular canal system) ------P <<==| =====| O | | =========== Demospongia (most living sponge species; leucon grade) R =M==| I | ============= Calcarea (calcareous sponges; includes ascon, sycon & leucon grades F ===| E | ========== Homoscleromorpha (coralline sponges; leucon grade) R ===| ------A | ======== Placozoa (placozoans, Trichoplax) M= METAZOA ==| ======== EUMETAZOA