Phylum PORIFERA Grant, 1836

Porifera

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Phylum PORIFERA Grant, 1836

Sponges

Compiler and date details

February 2012 - John N.A. Hooper, Queensland Museum

2005 - Updated by John N.A. Hooper

30 December 2002 - John N.A. Hooper, Queensland Museum, Brisbane, Queensland, Australia

1994 - Felix Wiedenmayer, Naturhistorisches Museum Basel, Basel, Switzerland

Diagnosis

Sessile metazoans possessing inhalant and exhalant pores connected by chambers lined by choanocytes. The outside and the canals are lined by pinacocytes (exo- and endopinacocytes respectively). Water is inhaled through small pores (10-100µm in diameter), traversing the afferent canals towards the choanocyte chamber, and is expelled through efferent canals and the larger exhalant osculum. Water currents are unidirectional, maintained by an active beating of a single layer of flagellated cells (choanocytes) usually contained within chambers. Food particles and oxygen are removed from the water by various cells, including the choanocytes. Other cells, including archaeocytes, are instrumental in transporting these respiratory and dietary products throughout the sponge body, in addition to other functions. Cells are highly mobile, such as those that move freely within an extracellular matrix made of fibrils of collagen (the mesohyl): archaeocytes, collenocytes, spiculocytes, spongocytes, glycocytes, cells with inclusions, etc. (see definitions of terms in Boury-Esnault & Rützler, 1997). Most of the cells, especially the archaeocytes, have an ability to continually evolve into several other cell types as required by the individual organism (totipotency), which provide the sponge with a plasticity for its organisation. Firmness of the sponge body is provided by (1) collagen fibrils of the mesohyl, (2) spongin fibres, and (3) an inorganic skeleton consisting of various supporting mineral elements composed of either calcareous (CaCO3) or silica (SiO2) (including discrete spicules, articulated or fused spicules and/or hypercalcified mineralised basal skeleton). Articulated and hypercalcified skeletons are absent in most Recent taxa, but were much more prevalent in fossil faunas ('lithistid' and 'sclerosponge' bauplans). These organic and inorganic materials are manufactured or otherwise engineered by various types of cells. Sponges have free-swimming or creeping larvae, although most groups have considerable means of asexual propagation, and all have extensive regenerative powers that appear to be vital for sustaining local populations. There are three distinct classes (Hexactinellida, Demospongiae and Calcarea), with the extinct class Archaeocyatha having suspected affinities with Demospongiae. The fossil 'classes' Sphinctozoa and Stromatoporoidea are obvious grades of construction and not phylogenetic clades (e.g., Wood 1991a), although distribution of the many lower taxa amongst the four well-established classes remains largely unresolved.

ID Keys

KEY TO RECENT PORIFERA
(1) Mineral skeleton absent----------------------------------------------------------------------Demospongiae
Mineral skeleton includes a ‘hypercalcified’ basal skeleton of solid limestone--------------------------2
Mineral skeleton consisting of discrete spicules--------------------------------------------------------------------3

(2) Soft parts contain siliceous spicules-----------------------------------------------------Demospongiae
Soft parts contain calcareous spicules (test with acid)------------------------------------------Calcarea

(3) Spicules siliceous, the larger ones are triaxone/hexactine (six-rayed), occurring both individually and
fused together-------------------------------------------------------------------------------------Hexactinellida
Spicules siliceous, the larger ones are tetraxone or monaxone----------------------Demospongiae
Spicules calcareous (test with acid), usually triactine or tetractine--------------------------Calcarea

Australian Biological Resources Study

Australian Faunal Directory