The calcareous sponges
of
class
Class or The Class may refer to:
Common uses not otherwise categorized
* Class (biology), a taxonomic rank
* Class (knowledge representation), a collection of individuals or objects
* Class (philosophy), an analytical concept used differentl ...
Calcarea are members of the animal phylum
Porifera, the cellular sponges. They are characterized by
spicule
Spicules are any of various small needle-like anatomical structures occurring in organisms
Spicule may also refer to:
*Spicule (sponge), small skeletal elements of sea sponges
*Spicule (nematode), reproductive structures found in male nematodes ( ...
s made of
calcium carbonate in the form of
calcite or
aragonite
Aragonite is a carbonate mineral, one of the three most common naturally occurring crystal forms of calcium carbonate, (the other forms being the minerals calcite and vaterite). It is formed by biological and physical processes, including pre ...
. While the spicules in most species have three points, in some species they have either two or four points.
Biology
All sponges in this class are strictly marine, and, while they are distributed worldwide, most are found in shallow tropical waters. Like nearly all other sponges, they are sedentary
filter feeders.
All three
sponge body plans are represented within class Calcarea : asconoid, syconoid, and leuconoid. Typically, calcareous sponges are small, measuring less than in height, and drab in colour. However, a few brightly coloured species are also known.
Calcareous sponges vary from radially symmetrical vase-shaped body types to colonies made up of a meshwork of thin tubes, or irregular massive forms. The skeleton has either a mesh or honeycomb structure.
Classification
Of the 15,000 or so species of Porifera that exist, only 400 of those are calcareans.
Calcarean sponges first appeared during the
Cambrian, and their diversity was greatest during the
Cretaceous period
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of t ...
. Recent molecular analysis suggests the class Calcarea should be designated as a
phylum, in particular the first to have diverged in the
Animal
Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motilit ...
ia.
The calcareous sponges are divided into two subclasses and six orders:
Class Calcarea
* Subclass
Calcinea
The Calcinea are a subclass of the calcareous sponges. Its phylum is Porifera and class is Calcarea. Branching is usually dichotomous or umbellate with anastomoses
An anastomosis (, plural anastomoses) is a connection or opening between tw ...
** Order
Clathrinida
The Clathrinida are an order of calcareous sponges found in marine environments. These sponges have an asconoid structure and lack a true dermal membrane or cortex. The spongocoel is lined with choanocytes
Choanocytes (also known as "collar ce ...
** Order
Murrayonida
The Murrayonida are an order of sea sponges in the subclass Calcinea.
Taxonomy
The order consists of four known species, in three families:
Family Murrayonidae Dendy & Row, 1913
* '' Murrayona phanolepis'' Kirkpatrick, 1910 - discovered by ...
* Subclass
Calcaronea
Calcaronea is a Class (biology), subclass of sea sponges in the class Calcarea. They are Calcarea with the triactines and the basal system of tetractines sagittal (i.e. the rays of the spicule make unequal angles with each other), exceptionally r ...
** Order
Baerida
Baerida is an order of sea sponges in the subclass of Calcaronea, first described in 2000 by Radovan Borojevic, Nicole Boury-Esnault and Jean Vacelet
Jean Vacelet is a French marine biologist who specialises in the underwater fauna of the Medit ...
** Order
Leucosolenida
Leucosolenida is an order of sponge
Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and cha ...
** Order
Lithonida
Minchinellidae is a family of calcareous sponges in the order Calcarea. It is the only family in the monotypic class Lithonida.
Description
Calcaronea with reinforced skeleton
consisting either of linked or cemented basal actines of
tetract ...
** Order
Pharetronida†
References
External links
UCMP: Calcarea
{{Taxonbar, from=Q209924
Taxa named by James Scott Bowerbank