- Hexasterophora
taxobox
image_caption =
name = Hexasterophora
regnum =Animalia
phylum =Porifera
classis =Hexactinellida
subclassis = Hexasterophora
subdivision_ranks = Orders
subdivision =Lyssacinosa Hexactinosa Lychniscosa Hexasterophora are sponges, a
subclass in the classHexactinellida . The Hexasterophora first appeared in the Ordovician and is separated into three orders, theLyssacinosa , theHexactinosa , and theLychniscosa , all of which have living representatives in the seas today.Hexasterophorans have skeletons composed of overlapping six-rayed
spicule s. The sponge is commonly firmly attached by its base to a hardsubstratum ; less often rooted by the anchoring spicules and rarely inserted directly into the loose bottom sediments. The three groups are differentiated by the extent of fusion of adjacent spicules.The Lyssacinosa, Hexactinosa, and Lychniscosa appear sequentially in the fossil record. The least fused group, the Lyssacinosa, appears in the
Ordovician , while the intermediate group, the Hexactinosa is known from theDevonian . Finally, the Lychniscosa, with the most tightly interlocking spicules is first found in rocks ofTriassic age.
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