Archaeocyatha Fossil range: Early - Mid Cambrian
Scientific classification
Domain: Eukaryota Kingdom: Animalia or Metazoa Subkingdom: Parazoa Phylum: Porifera (sponges) (unranked) Archaeocyatha

*1 – Gap (intervallum)
*2 – Central cavity *3 – Internal wall *4 – Pore (all the walls and septa have pores, not all are represented) *5 – Septum *6 – External wall *7 – Rizoid

The Archaeocyatha or archaeocyathids ("ancient cups") were sessile, reef-building^[1] marine organisms of warm tropical and subtropical waters that lived during the early (lower) Cambrian period. The Cambrian is a geologic period and system that began about Ma (million years ago at the end of the Proterozoic eon and ended about Ma with Animals Plants fungi, and Protists are eukaryotes (juːˈkærɪɒt or -oʊt Organisms whose cells are organized into complex The Parazoa are an ancestral subkingdom of Animals literally translated as "beside the animals" The sponges or poriferans (from Latin porus "pore" and ferre "to bear" are Animals Sessile is a term in Biology with two distinct meanings In botany and medicine In Botany, sessile means "without a stalk In nautical terminology a reef is a rock, sandbar, or other feature lying beneath the surface of the water (six fathoms or less at low water Marine is an Umbrella term. As an adjective it is usually applicable to things relating to the Sea or Ocean, such as Marine biology, Marine The Cambrian is a geologic period and system that began about Ma (million years ago at the end of the Proterozoic eon and ended about Ma with They are first known from the beginning of the Tommotian Age of the Cambrian, about 530 million years ago (mya), and quickly diversified into over a hundred families. The Tommotian Age, named after the Mollusc Tommotia, which began approx In Astronomy, Geology, and Paleontology, mya or " mya " is an abbreviation for "million years ago". Speciation is the Evolutionary process by which new biological Species arise In Biological classification, family ( Latin They became the planet's very first reef building animals. In nautical terminology a reef is a rock, sandbar, or other feature lying beneath the surface of the water (six fathoms or less at low water

Today, the archaeocyathan families are recognizable by small but consistent differences in their fossilized structures: Some archaeocyathans were built like nested bowls, while others were as long as 30 cm. FOSSIL is a standard protocol for allowing serial communication for Telecommunications programs under the DOS Operating system. Some archaeocyaths were solitary organisms, while others formed colonies. In Biology, a colony (from Latin colonia) refers to several individual Organisms of the same Species living closely together usually Then, around 520 mya, the archaeocyaths went into a sharp decline. In Astronomy, Geology, and Paleontology, mya or " mya " is an abbreviation for "million years ago". Almost all species became extinct by the Middle Cambrian, with the final-known species disappearing just prior to the end of the Cambrian period. In Biology and Ecology, extinction is the cessation of existence of a Species or group of taxa. ^[2] Their rapid decline and disappearance coincided with a rapid diversification of the Demosponges. An adaptive radiation is a rapid Evolutionary radiation characterized by an increase in the morphological and ecological diversity of a single rapidly diversifying lineage The Demospongiae are the largest class in the Phylum Porifera.

The typical archaeocyathd resembled a hollow horn coral. The Rugosa Rose is also sometimes just called "Rugosa" The Rugosa, also called the Tetracoralla, are an extinct order Each had a conical or vase-shaped porous skeleton of calcite similar to that of a sponge. In Biology, the skeleton is a strong and often a rigid framework that supports the body of an animal holding it upright and giving it shape and strength (Also skeletal Calcite is a carbonate mineral and the most stable polymorph of Calcium carbonate ( Ca[[carbon C]] O 3 The sponges or poriferans (from Latin porus "pore" and ferre "to bear" are Animals The structure appeared like a pair of perforated, nested ice cream cones. Their skeletons consisted of either a single porous wall (Monocyathida), or more commonly as two concentric porous walls, an inner and outer wall separated by a space. Inside the inner wall was a cavity (like the inside of an empty ice cream cone). At the base, these pleosponges were held to substrate with holdfast. A holdfast is a Root -like structure that anchors aquatic Sessile organisms such as Seaweed, other sessile Algae, stalked The body presumably occupied the space between the inner and outer shells (the intervallum). Flow tank experiments suggest that archaeocyathan morphology allowed them to exploit flow gradients, either by passively pumping water through the skeleton, or, as in present-day, extant sponges, by drawing water through the pores, removing nutrients, and expelling spent water and wastes through the pores into the central space. The term morphology in Biology refers to the outward appearance ( Shape, Structure, Colour, Pattern) of an Organism In Biology, the skeleton is a strong and often a rigid framework that supports the body of an animal holding it upright and giving it shape and strength (Also skeletal Extant is a term commonly used to refer to Taxa (such as Species, genera or families) that are still in existence (living

The archaeocyathans inhabited coastal areas of shallow seas. Their widespread distribution over almost the entire Cambrian world, as well as the taxonomic diversity of the species, might be explained by surmising that that they were planktonic during their larval stage. Taxonomy is the practice and science of classification The word comes from the Greek, taxis (meaning 'order' 'arrangement' and, nomos In Biology, a species is one of the basic units of Biological classification and a Taxonomic rank. Plankton consist of any drifting Organisms ( Animals Plants Archaea, or Bacteria) that inhabit the Pelagic zone of A larva ( Latin; plural larvae) is a juvenile form of Animal with indirect development, undergoing Metamorphosis (for example

Their phylogenetic affiliation has been subject to changing interpretations: Yet the consensus is growing that the archaeocyath was indeed a kind of sponge,^[3]thus sometimes called a pleosponge. But some invertebrate paleontologists have placed them in an extinct, separate phylum, known appropriately as the Archaeocyatha. An invertebrate is an Animal lacking a Vertebral column. The group includes 98% of all animal Species — all animals except those in the Chordate Palaeontology redirects here For the Scientific journal, see Palaeontology (journal. A phylum ( Plural: phyla) is a Taxonomic rank between Kingdom and above Class. ^[4] However, one cladistic analysis^[5] suggests that Archaeocyatha is a clade nested within the phylum Porifera (better known as the true sponges). Cladistics is the hierarchical classification of Species based on evolutionary ancestry A clade is a taxonomic group comprising a single Common ancestor and all the descendants of that ancestor A phylum ( Plural: phyla) is a Taxonomic rank between Kingdom and above Class. The sponges or poriferans (from Latin porus "pore" and ferre "to bear" are Animals

Notes

1. ^ Archaeocyathid reef structures ("bioherms"), although not as massive as later coral reefs, might have been as deep as ten meters (Emiliani 1992:451).
2. ^ The last-recorded archaeocyathan is a single species from the late (upper) Cambrian of Antarctica.
3. ^ Scuba divers have discovered living calcareous sponges, including one species that -- like the archaeocyathans -- is without spicules, thus morphologically similar to the archaeocyaths. Calcium carbonate is a Chemical compound with the Chemical formula Ca[[Carbon C]] O 3 This article is about the skeletal structure See also Spicule (solar physics and Spicule (glass manufacture. (Rowland 2001).
4. ^ Debrenne, F. and J. Vacelet. 1984. "Archaeocyatha: Is the sponge model consistent with their structural organization?" in Palaeontographica Americana, 54:pp358-369.
5. ^ J. Reitner. 1990. "Polyphyletic origin of the 'Sphinctozoans'", in Rutzler, K. (ed. ), New Perspectives in Sponge Biology: Proceedings of the Third International Conference on the Biology of Sponges (Woods Hole) pp. 33-42. Smithsonian Institution Press, Washington, DC.

References

• Emiliani, Cesare, Planet Earth 1992, p 451

External links

• (UCMP Berkeley) Archaeocyathans
• (Palaeos Invertebrates) Archaeocyatha