Calcarea

(Calcareous sponges)

Phylum Porifera

Class Calcarea

Number of families 22

Thumbnail description
Marine sponges with calcareous skeletal elements (spicules)

Evolution and systematics

The fossil record of unambiguously identified Calcarea is relatively poor and fragmented. Most calcareous sponges in the fossil record were classified as either stromatoporoids, chaetetids, archaeocyaths, inozoans, pharetronids, or sphinctozoans. They are common in the Paleozoic and Mesozoic, however, rare in the Cenozoic. It is now established that many of these forms actually belong to several groups of demosponges because of the possession of primary siliceous spicules, and only few to Calcarea (pharetronids and some sphinctozoans). Identification of "true" calcareous sponges in the fossil record is difficult because fossil remains often lack diagnostic spicules at all. Heteractinida, characterized by a spiculate (consisting of six-rayed heteractinid octactines, polyactines) and aspiculate calcitic skeleton, are now regarded as an extinct order of Calcarea, restricted to the Paleozoic. The oldest probable calcareous sponge with affinities to modern subclass Calcaronea (Gravestockia pharetroniensis Reitner, 1992) was described from the lower Cambrain of South Australia. The assignment of many records of so-called "Pharetronida," calcareous sponges with a rigid calcareous skeleton, to subclasses Calcaronea or Calcinea is difficult if they do not possess characteristic spicules to allow precise assignment. However, most Pharetronids probably belong to subclass Calcaronea. The majority of modern spiculate calcareans would be found as dissociated spicules in the fossil record; there is only one record from the middle Jurassic at King's Sutton, Northamptonshire, where the form and arrangement of a calcareous sponge was preserved (Leucandra walfordi Hinde, 1893).

Calcarea are regarded as one of four classes of the phylum Porifera (three extant [Demospongiae, Hexactinellida, Calcarea] and one fossil [Archaeocyatha]), distinctive in possessing a spicule skeleton composed exclusively of calcium carbonate and being the only poriferan taxon realizing all three stages of development of the aquiferous system (asconoid-syconoid-leuconoid). There is still dispute about the true phylogenetic relationships of the three extant sponge classes, including also the relationship of the class Calcarea to other (higher) diploblastic taxa like Ctenophora and Cnidaria. Two competing hypotheses group a) Hexactinellida + Demospongiae more closely together based on the possession of silicious spicules ("Silicea") in contrast to Calcarea ("Calcispongia") and b) Demospongiae more closely with Calcarea based on the possession of a cellular pinacoderm ("Cellularia"/"Pinacophora") to the exclusion of Hexactinellida, which possess a cyncitial tissue structure ("Symplasma"). Both proposals, however, assume poriferan monophyly. More recently, several authors have suggested from ribosomal DNA sequence data that Calcarea might be more closely related to the phyla Ctenophora/Cnidaria than to the other two extant classes of Porifera, rendering phylum Porifera paraphyletic. Class Calcarea was elevated to phylum status ("Calcispongia," a term that was already used in the mid-nineteenth century) (Zrzavy, et al., 1998; Borchiellini, et al., 2001), but as yet without robust statistical support (e.g., Medina, et al., 2001). However, this proposal is not followed in the most comprehensive systematic treatment of sponges to date, the Systema Porifera (Hooper and Van Soest, 2002) and the issue of sponge paraphyly is at the time of writing (2003) far from being resolved. Therefore, it should be regarded as still contentious until further corroboratory data, such as a molecular multi-locus approach, is presented. However, new chemotaxonomic data from lipid biomarkers (Thiel, et al., 2002) support a closer relationship of Hexactinellida and Demosponges. Although this

confirms that Calcarea are chemotaxonomically different from "Silicosponges" or "Silicea" (Demospongiae + Hexactinellida), it does not necessarily imply sponge paraphyly.

Number of classes and families: 1 class (Calcarea); 2 subclasses (Calcinea, Calcaronea); 5 orders (2 in Calcinea: Clathrinida, Murrayonida; 3 in Calcaronea: Leucosoleniida, Lithonida, Baeriida); 22 families; 75 genera; about 500 described species.

Physical characteristics

Calcareous sponges are mostly small and inconspicious; they occur in a variety of forms, as single tubes, sometimes vase shaped, a mass of small tubes ("cormus"), a bushy arrangement of single tubes, or sometimes massive without any apparent symmetry. Three types of aquiferous system are realized in Calcarea: asconoid, all internal cavities are lined by choanocytes (flagellated cells) without folding of the choanoderm; syconoid, simple folding of the choanoderm; and leuconoid, choanocytes are arranged in discrete "choanocyte chambers."

Calcareous sponges range from minute size an inch or less (few millimeters), to about a maximum of about 12 in (30 cm) (Pericharax heteroraphis). They are mostly colorless (whitish to beige), sometimes bright yellow (Leucetta chagosensis), dark greenish-brown (Pericharax heteroraphis), or fluorescent red/orange (Leucetta microraphis, sometimes).

Calcareous sponges have a skeleton that is made of calcium carbonate (calcite), composed of free diactines, triactines, tetracines, and/or polyactine spicules, to which a solid basal calcitic skeleton may be added, with either cemented basal spicules or which is fully embedded in an enveloping calcareous cement. Calcareans are viviparous and have blastula larvae.

Distribution

Calcareous sponges are found globally in all oceans, from intertidal to the deep sea, but not the abyss.

Habitat

Calcareous sponges live in diverse habitats. In tropical coral reefs, they dwell mainly in shaded and/or cryptic habitats and prefer calmer waters.

Behavior

Not applicable; calcareous sponges are sessile filter feeders.

Feeding ecology and diet

Calcareous sponges are sessile filter feeders, whose main diet is dissolved organic matter and small particulate matter (bacteria) filtered from seawater by pumping activity.

Reproductive biology

Calcareous sponges have internal fertilization, with egg size ranging from 25 to 100 µm. They are sexual and viviparous, with some species probably asexual by budding.

Conservation status

No species are listed by the IUCN.

Significance to humans

There is no known significance of calcareous sponges to humans.

Species accounts

List of Species

No common name

Clathrina heronensis

order

Clathrinida

family

Clathrinidae

taxonomy

Clathrina heronensis Wörheide & Hooper, 1999, Heron Island, at Wistari Channel, Great Barrier Reef.

other common names

None known.

physical characteristics

Mass of loosely anastomosing tubes, approximately 0.04 in (1 mm) diameter, with fairly large space between tubes, whole sponge 1.2 × 0.8 in (3 × 2 cm), flat. Life color white. No visible oscules nor distinct exhalant system. With soft, compressible, and delicate texture, smooth surface. Skeleton consists solely of a layer of irregular triactines. Triactines tangentially orientated, actines sometimes overlap. No differentiation or zonation of skeleton, appears to be uniform throughout cormus (sponge body). Asconoid grade of aquiferous system. One type of triactines, with a more-or-less blunt tip, actines measuring 80–130 × 8–12µm.

distribution

Currently only known from the Great Barrier Reef, Australia. Putative member of the cosmopolitan species group Clathrina coriacea.

habitat

Cryptic, under rubble at reef crest, intertidal.

behavior

Sessile.

feeding ecology and diet

Sessile filter feeder.

reproductive biology

Viviparous, not much known.

conservation status

Not listed by the IUCN.

significance to humans

None known.

Lemon-sponge

Leucetta chagosensis

order

Clathrinida

family

Leucettidae

taxonomy

Leucetta chagosensis Dendy, 1913, Chagos Archipelago, Indian Ocean.

other common names

None known.

physical characteristics

Massive, globular, slightly elongated-globular to pyriform or elongate growth form. Specimens range from 0.39–2.0 in (1–5 cm) in size. Bright yellow color in life (while alive). Globular specimens with one prominent osculum with a naked "lip." Elongated specimens with a few oscules with a naked "lip" on the ridge of the sponge body. Firm and smooth, with slightly translucent surface. With a distinct thin cortex, up to 50 µm thick, sustained by tangentially arranged small regular triactines (three rayed "mercedes-star" spicules), with some large triactines also scattered tangentially in the cortex. Small subdermal cavities present (50–150 µm diameter). Choanocyte-chamber free zone of sub-dermal cavities with a thickness of up to 250 µm. Large regular triactines also found here. A peculiar, special, small sagittal triactine only found in the oscular rim ("lip"). Dense irregular meshwork of small regular triactines form choanoskeleton. Larger triactines occasionally irregularly scattered in the choanosome in small numbers. Small tetractines (four-rayed spicules) concentrated around exhalant canals. Leuconoid aquiferous system. Spicules small: larger regular triactines about 250–500 25–50 µm, smaller regular triactines 100–200 10–25 µm; regular tetractines of the excurrent canals 90–125 10–20 µm.

distribution

Probably circum Indo-Pacific, from (southern) Red Sea to French Polynesia in most tropical coral reefs. Recorded from Indo-West Pacific, in Western Australia (Houtman Abrolhos, Fremantle), Queensland (Great Barrier Reef); also Indian Ocean (Chagos) and western Pacific (New Caledonia, Fiji, Vanuatu, French Polynesia).

habitat

In crevices and under overhangs of coral bommies, also abundant in illuminated reef habitats.

behavior

Sessile.

feeding ecology and diet

Sessile filter feeder.

reproductive biology

Viviparous, not much known.

conservation status

Not listed by the IUCN.

significance to humans

None known.

No common name

Pericharax heteroraphis

order

Clathrinida

family

Leucettidae

taxonomy

Pericharax carteri heteroraphis Poléjaeff, 1883, Tristan da Cunha (South Atlantic).

other common names

None known.

physical characteristics

Massive, bulbous, rarely clavate growth form. Small and young specimens pyriform, with external surface not folded; older and larger specimens with characteristic irregularly folded external surface. Maximum size of about 12 in (30 cm) in height. Yellow greenish to dark greenish brown color in life, one large terminal osculum always present, mostly with a "lip." Firm, harsh texture, surface smooth but brittle, large triactines protruding through the surface readily visible. With a thin but distinct, up to 50 µm thick, cortex consisting of tangentially aligned small, characteristic tripod-like triactines, but small and large triactines also present. Sub-dermal cavities present in most areas below the cortex (50–200 µm diameter), devoid of choanocyte chambers. Sub-dermal cavity zone up to 400 µm thick. Dense irregular meshwork of mainly regular small triactines forms the choanosomal skeleton. Some small tetractines also. Many large "giant" triactines irregularly dispersed throughout the choanosome. Small tetractines concentrated at, but not restricted to, excurrent water canals. Leuconoid aquiferous system. Large regular triactines 500–1,600 70–200 µm; smaller regular triactines 120–200 15–25 µm; tetractines 90–180 10–20 µm; tripod-like cortical sagittal triactines 45–130 7–15 µm.

distribution

Widely distributed, allegedly nearly cosmopolitan. From tropical coral reefs (e.g., Great Barrier Reef) to the Subantarctic, also south Atlantic, Indian Ocean, and Indo-Malayan region.

habitat

Widely distributed in exposed and semi-shaded habitats, sometimes under overhangs.

behavior

Sessile.

feeding ecology and diet

Sessile filter feeder.

reproductive biology

Viviparous. Not much known.

conservation status

Not listed by the IUCN.

significance to humans

None known.

No common name

Soleneiscus radovani

order

Clathrinida

family

Soleneiscidae

taxonomy

Soleneiscus radovani Wörheide & Hooper, 1999, south side of Wistari Reef, Great Barrier Reef, 56 ft (17 m) depth.

other common names

None known.

physical characteristics

Aborescent, bushy, with single, delicate tubes branching dichotomous and polychotomous from a few central tubes. Bright yellow color. Central, proximal tube larger than the distal tubes; tubes ramify only in the lower part of the sponge "bush." Distal parts of tubes mostly longer than ramified parts. Single tubes approximately 0.08 in (2 mm) in diameter. Size of the sponge "bush" is less than 4 in (10 cm). One naked osculum on top of each tube. Soft and delicate texture, easily torn. Sagittal tetractines only make up skeleton. Tangentially arranged facial plane of tetractines forms wall of tubes, with the longer ray of basal triradiate system pointing in direction of central tube (growth axis). The curved and free actines of tetractines protrude into tube, tips of the free actines bent in direction of osculum. Asconoid grade of aquiferous system. Only one spicule type is present. Non-curved, longer unpaired actine of basal triradiate system approximately 120–200 µm × 8–12 µm, the paired shorter (curved) actines of pseudosagittal basal plane approximately 85–130 × 8–12 µm.

distribution

Currently only described from the Great Barrier Reef, probably wider distribution in the tropical western Pacific.

habitat

Small patches of coral, under overhangs.

behavior

Sessile.

feeding ecology and diet

Filter feeder.

reproductive biology

Viviparous, details not known.

conservation status

Not listed by the IUCN.

significance to humans

None known.

No common name

Sycon capricorn

order

Leucosoleniida

family

Sycettidae

taxonomy

Sycon capricorn Wörheide & Hooper, 2003, south side of Heron Island, Great Barrier Reef.

other common names

None known.

physical characteristics

Tubular and mostly branching growth form. If small, only a single tube with a few smaller branches arising from a narrower base. Otherwise bushy, with multiple dichotomous or occasionally polychotomous branching digits. Apical oscule of each branch always fringed. Digitations with a diameter of 0.2–0.4 in (0.5–1 cm). Beige color in life. Smooth, soft, tesselated texture. No defined cortex (i.e., with tangentially arranged spicules). Ectosomal skeleton (forming the external surface) consists of characteristic "tufts" of bundled free actines of t-shaped sagittal triactines and two types of microdiactines. Tufts, with a diameter of 100–150 µm, form minute tessellation of external sponge surface, located over radially arranged choanocyte chambers. Long, thin diactines around the osculum, sustaining the oscular fringe, with a size of 200–600 × 7–15 µm. Choanosomal skeleton composed of two types of sagittal t-shaped triactines in articulated arrangement. First type (shorter unpaired actines) builds walls of tubular choanocyte chambers, with size of unpaired actines 69–170 × 5–15 µm, the paired actines are 40–95 µm long. Second type only found in the distal parts of the choanocyte chamber-tubes, with size of unpaired actines 150–290 × 4–15 µm, length paired actines 40–80 µm. Their longer, unpaired actines contributes to ectosomal tessellation, with brush-like tufts of microdiactines arranged around them. Sinuous fusiform diactines of spicule tufts with a size of 70–180 × 3–12 µm, and smaller microdiactines with a characteristic "ball"-type thickening, with a size of 55–75 × 7–12 µm. Atrial skeleton of sagittal triactines and tetractines, their elongated free unpaired/apical actines protruding into atrium, with a size of 45–230 × 6–15 µm. Syconoid grade of aquiferous system.

distribution

Currently only known from the Great Barrier Reef, Australia. Member of the allegedly more widespread Sycon gelationosum/arborea species group.

habitat

Cryptic, mostly in caves and under overhangs, rarely in the open.

behavior

Sessile.

feeding ecology and diet

Sessile filter feeder.

reproductive biology

Viviparous, amphiblastula larva.

conservation status

Not listed by the IUCN.

significance to humans

None known.

No common name

Grantiopsis heroni

order

Leucosoleniida

family

Lelapiidae

taxonomy

Grantiopsis heroni Wörheide & Hooper, 2003, northern side of Wistari Reef, Great Barrier Reef.

other common names

None known.

physical characteristics

Mass of branching and anastomosing tubes, about 2 1.2 0.8 in (5 3 2 cm) in size. Tubes anastomose in proximal part of cormus at the base, but become unified and only partly branching in distal part. With a terminal osculum of about 0.20 in (5 mm) diameter. White color in life, soft texture, no surface ornamentation. With a distinct cortex of tangentially arranged thick sagittal triactines, with more-or-less cylindrical actines and an unpaired angle of up to 160°. Paired actines with a size of 220–350 µm, unpaired actines 210–370 µm, maximum thickness 15–40 µm. Ectosomal membrane (exopinacoderm) supported by perpendicularly arranged micro-diactines, restricted to the ectosomal (distal) part of cortex, 40–100 µm long, often finely spined. Sometimes small subcortical cavities, with diameter of 50–100 µm. Inarticulated choanoskeleton only supported by two (non-articulated) spicules, apical actines of sub-atrial sagittal tetractines and nail-shaped triactines (with totally reduced paired actines). With a size of 140–350 4–12 µm. Nail-shaped triactines pointing with "unpaired" actines towards cortex, unpaired actines of the sub-atrial triactines do not extend to the cortex. Subatrial sagittal tetractines delimit choanosome towards atrial skeleton with their regular basal triradiate system, their elongated apical actine forms proximal part of choanoskeleton. Actines of basal triradiate system 30–80 µm long, longer apical actine 130–330 µm long. The atrial skeleton is supported by sagittal tetractines with their curved free actines pointing towards and into the atrium. Spicule with a "plough-like" shape. Apical actine, with a size of 65–120 µm, bent towards unpaired actine of basal triradiate system. Basal triradiate actines are 30–75 µm long, with maximum thickness of 2–12 µm. Syconoid grade of aquiferous system.

distribution

Currently only known from the Great Barrier Reef, Australia. Putative member of the allegedly more widespread Grantiopsis cylindrica species group.

habitat

Overhangs, swim throughs and crevices between coral bommies at the reef edge.

behavior

Sessile.

feeding ecology and diet

Sessile filter feeder.

reproductive biology

Viviparous.

conservation status

Not listed by the IUCN.

significance to humans

None known.

No common name

Petrobiona masselina

order

Lithonida

family

Petrobionidae

taxonomy

Petrobiona masselina Vacelet & Levi, 1958, Mediterranean.

other common names

None known.

physical characteristics

Massive, subspherical or multi-lobate growth form, encrusting in high energy habitats or dead stalk in calm habitats. Maximum size of up to 2.4 in (6 cm) in diameter when encrusting, if not, living "head" of 0.39–0.47 in (1.0–1.2 cm) in diameter with a stalk 0.79 in (2 cm) long. Stony texture, white color, smooth surface. In subspherical specimens apical oscules, 600–800 µm in diameter. Living tissue only located at the surface and between crests of basal skeleton, with a choanosome 600 µm thick. Spicules are sagittal triactines (with actines 25–200 6–40 µm), tuning-fork (diapason) triactines (basal actines 30–70 5–8.5 µm, apical actines 20–50 4–7 µm), two size categories of tetractines (pugioles) (apical actines 40–130 22–28 µm and 16–40 5.5–8.5 µm, actines of basal triradiate system 8–100 10–28 µm and 30–70 5.5–8.5 µm), spined microdiactines 30–60 2–3 µm. Elongate, irregular skeletal elements, with a radial orientation of the crystals giving them a pseudo-spherulitic appearance, form solid calcareous basal skeleton of Mg-calcite, with crests and depressions on the surface. Some spicules entrapped in basal skeleton, randomly arranged. Leuconoid grade of aquiferous system.

distribution

Mediterranean: eastern basin (Adriatic, Ionian Sea, Crete, Malta, Tunisia), western part of the eastern basin (not recorded west of the Rhone delta and Algeria).

habitat

Common near the entrance of dark caves, more rarely on the under surface of stones, 1.6–82 ft (0.5–25 m) depth.

behavior

Sessile.

feeding ecology and diet

Sessile filter feeder.

reproductive biology

Viviparous. Amphiblastula larva.

conservation status

Not listed by the IUCN.

significance to humans

None known.

Resources

Books

Borojevic, R., N. Boury-Esnault, M. Manuel, and J. Vacelet. "Order Baerida." In Systema Porifera, edited by J. N. A. Hooper and R. W. M. Van Soest. New York: Plenum, 2002.

——. "Order Clathrinida Hartman, 1958." In Systema Porifera, edited by J. N. A. Hooper and R. W. M. Van Soest. New York: Plenum, 2002.

——. "Order Leucosolenida Hartman, 1958." In Systema Porifera, edited by J. N. A. Hooper and R. W. M. Van Soest. New York: Plenum, 2002.

Fell, P. E. "Porifera." In Reproductive Biology of Invertebrates. Volume I: Oogenesis, Oviposition and Oosorption, edited by K. G. Adiyodi, and R. G. Adiyodi. New York: John Wiley and Sons, 1983.

——. "Porifera." In Reproductive Biology of Invertebrates. Volume IV: Fertilization, Development, and Parental Care (Part A), edited by K. G. Adiyodi, and R. G. Adiyodi. New York: John Wiley and Sons, 1989.

——. "Porifera." In Reproductive biology of invertebrates. Volume 6 Part A: Asexual propagation and reproductive strategies, edited by K. G. Adiyodi, and R. G. Adiyodi. Chichester, New York: John Wiley and Sons, 1993.

——. "Poriferans, the Sponges." In Embryology: constructing the organism, edited by S. F. Gilbert, and A. M. Raunio. Sunderland, MA: Sinauer Associates, Inc., Publishers, 1997.

Hooper, J. N. A., and R. W. M. Van Soest, eds. Systema Porifera. Guide to the Supraspecific Classification of Sponges and Spongiomorphs (Porifera). New York: Plenum, 2002.

Lévi, C., ed. Sponges of the New Caledonian Lagoon. Paris: Orstom, 1998.

Manuel, M., R. Borojevic, N. Boury-Esnault, and J. Vacelet. "Class Calcarea Bowerbank, 1864." In Systema Porifera, edited by J. N. A. Hooper and R. W. M. Van Soest. New York: Plenum, 2002.

Pickett, J. "Fossil Calcarea. An overview." In Systema Porifera, edited by J. N. A. Hooper and R. W. M. Van Soest. New York: Plenum, 2002.

Vacelet, J., R. Borojevic, N. Boury-Esnault, and M. Manuel. "Order Lithonida Vacelet, 1981, recent." In Systema Porifera, edited by J. N. A. Hooper and R. W. M. Van Soest. New York: Plenum, 2002.

——. "Order Murrayonida Vacelet, 1981." In Systema Porifera, edited by J. N. A. Hooper and R. W. M. Van Soest. New York: Plenum, 2002.

Periodicals

Borchiellini, C., M. Manuel, E. Alivon, N. Boury-Esnault, J. Vacelet, and Y. Le Parco. "Sponge paraphyly and the origin of Metazoa." Journal of Evolutionary Biology 14, no. 1 (2001): 171–179.

Medina, M., A. G. Collins, J. D. Silberman, and M. L. Sogin. "Evaluating hypotheses of basal animal phylogeny using complete sequences of large and small subunit rRNA." Proceedings of the National Academy of Science of the USA 98, no.17 (2001): 9707–9712.

Thiel, V., M. Blumenberg, J. Hefter, T. Pape, S. A. Pomponi, J. Reed, J. Reitner, G. Wörheide, and W. Michaelis. "A chemical view on the most ancestral Metazoa—biomarker chemotaxonomy of hexactinellid sponges." Naturwissenschaften 89 (2002): 60–66.

Wörheide, G., and J. N. A. Hooper. "Calcarea from the Great Barrier Reef. 1: Cryptic Calcinea from Heron Island and Wistari Reef (Capricorn-Bunker Group)." Memoirs of the Queensland Museum 43, no. 2 (1999): 859–891.

——. "New species of Calcaronea (Porifera: Calcarea) from cryptic habitats of the southern Great Barrier Reef (Heron Island and Wistari Reef, Capricorn-Bunker Group, Australia)." Journal of Natural History 37 (2003): 1–47.

Zrzavy, J., S. Mihulka, P. Kepka, A. Bezdek, and D. Tietz. "Phylogeny of the Metazoa based on morphological and 18S ribosomal DNA evidence." Cladistics 14, no. 3 (1998): 249–285.

Other

Atlas of Sponges. (2 July 2003). <http://www.ulb.ac.be/sciences/biodic/EImAnatepon.html>.

Gert Wörheide, PhD