''Sporolithon ptychoides'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of crustose red

seaweed Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, marine algae. The term includes some types of '' Rhodophyta'' (red), ''Phaeophyta'' (brown) and ''Chlorophyta'' (green) macroalgae. Seaweed species such as ...

with a hard, calcareous skeleton in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Corallinaceae The Corallinaceae are one of the two extant Coralline families of red algae; they are differentiated from the morphologically similar Sporolithaceae by their formation of grouped sporangial chambers, clustered into sori. The Corallinoideae ...

. It has a widespread distribution, being present in the Pacific and Indian Oceans, the Mediterranean Sea and the southwestern Atlantic Ocean.

Description

In the southwestern Atlantic off the coast of Brazil, ''Sporolithon ptychoides'' forms rhodoliths up to in diameter. The surface of the rhodolith is crustose in places and knobbly in others. The internal arrangement is monomerous in the crustose portions and radial in the protrusions. The tetrasporangial compartments are grouped together and raised above the surrounding surface, while old, empty compartments become immersed in the

thallus Thallus (plural: thalli), from Latinized Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. Many of these organisms wer ...

; these tend to be aligned in rows. In the southwestern Indian Ocean off the coast of Natal, this species does not form rhodoliths, instead being crustose, with flat or knobbly

sometimes loosely and sometimes securely attached to the substrate. The patches are thick and up to across, with ragged margins and a flaking surface.

Distribution and habitat

''Sporolithon ptychoides'' is the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

of the genus ''

Sporolithon ''Sporolithon'' is a genus of red coralline algae in the family Sporolithaceae, in the order Corallinales. Species the World Register of Marine Species The World Register of Marine Species (WoRMS) is a taxonomic database that aims to provide ...

'', and the type location is the

Red Sea The Red Sea ( ar, البحر الأحمر - بحر القلزم, translit=Modern: al-Baḥr al-ʾAḥmar, Medieval: Baḥr al-Qulzum; or ; Coptic: ⲫⲓⲟⲙ ⲛ̀ϩⲁϩ ''Phiom Enhah'' or ⲫⲓⲟⲙ ⲛ̀ϣⲁⲣⲓ ''Phiom ǹšari''; T ...

. It has been found in the Mediterranean Sea, the Red Sea, the Indian Ocean and the Pacific Ocean, and more recently has been detected in the Atlantic Ocean off the coast of Brazil. Its typical habitat in Natal is rock pools, surge channels, and exposed rock in the shallow

subtidal zone The neritic zone (or sublittoral zone) is the relatively shallow part of the ocean above the drop-off of the continental shelf, approximately in depth. From the point of view of marine biology it forms a relatively stable and well-illuminated ...

on offshore coral reefs. In Brazil, it was in deeper water.

Ecology

This is one of several species of crustose coralline red algae that form rhodoliths on the seabed in the southwestern Atlantic. Rhodoliths are clumps of calcareous material that resemble

coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and sec ...

s but are not attached to the substrate. They do not feed on

plankton Plankton are the diverse collection of organisms found in Hydrosphere, water (or atmosphere, air) that are unable to propel themselves against a Ocean current, current (or wind). The individual organisms constituting plankton are called plankt ...

as corals do, but obtain their energy solely through

photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...

. Six or more species of the algae can be found forming rhodoliths in a relatively small area, and some of these rhodoliths are composed of several species of coralline alga overgrowing each other.

References

{{Taxonbar, from=Q37915895 Florideophyceae