Halichondrida order

The demosponge subclasses Tetractinomorpha and Ceractinomorpha are primarily defined by oviparous or viviparous larval development, respectively. This division is the subject of some dispute as there have been indications that the reproductive mode may be ecologically dependent and thus not a stable character for classification. There are 12 orders in the subclasses Tetractinomorpha and Ceractinomorpha, with the largest number of metabolites reported from the orders Halichondrida (424), Haplosclerida (489), and Dictyoceratida (663). 

Over half of the compounds reported for lithistid sponges were isolated from Theonella (family Theonellidae). Theonella species have been reported to contain a wide variety of cyclic and linear peptides and polyketides, as well as 3-alkyl piperidine derivatives nearly identical to those reported from the order Haplosclerida.58 There is also a single report of cyano- and isothiocyano-sesquiter-penes similar to those isolated from Axinellidae (order Halichondrida).42 Bewley et al. performed a cellular localization study on Theonella swinhoei in which several types of microorganisms were separated from the sponge cells. Chemical analysis of the extracts from the separated cells indicated that the bicyclic peptide theopalauamide was found exclusively in filamentous bacteria while the polyketide swinholide A was localized to a mixed population of unicellular bacteria.59... 

Several long-chain brominated acids have been characterized among the membrane phospholipids of certain sponges (mainly in the PE class). Their main characteristic is the vinylic position of bromine, on carbon 6 of a 5,9-dienic system, and though they are apparently demospon-gic acids some examples have been found in several species of cnidarians (Dembitsky and Srebnik, 2002). They are therefore not specific to demosponges. Several species of the order Halichondrida harvested off the coast... 

Unlike A-nor steroids, which occur mainly in the family Axinellidae, sterols with polymethylated side chains are present in most orders, espedally Haplosderida and Ver-ongida, but also Astrophorida, Spirophorida, Halichondrida and Dictyoceratida (see below). 

In the classification of Bergquist (1978), order Halichondrida comprises the two families Halichondriidae and Hymenia-cidonidae, in that of Hooper (2000) it has four - Axinellidae, Desmoxyidae, DictyoneHidae and Halichondriidae - and in Systema Porifera, it has five - the four present in Hooper s scheme and the newfamily Bubariidae. As we have already... 

Castellanos, L., Zea, S., Osomo, O., and Etuque, C. (2003) Phylogenetic analysis of the order Halichondrida (Porifera, Demospongiae), using 3 3-hydroxysterols as chemical characters. Biochem. Syst. Ecol., 31, 1163-1183. 

Blumenberg, M. and Michaelis, W. (2007) High occurrence of brominated lipid fatty acids in boreal sponges of the order Halichondrida. Mar. Biol., 150,1153-1169. 

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