''Spongites yendoi'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

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 ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

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 is found on the lower shore as part of a diverse community in the southeastern Atlantic and the Indo-Pacific Oceans.

Description

''Spongites yendoi'' is a hard, encrusting species of coralline algae. Like other species it contains

chlorophyll Chlorophyll is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words (, "pale green") and (, "leaf"). Chlorophyll allows plants to absorb energy ...

and uses

photosynthesis Photosynthesis ( ) is a system of biological processes by which photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical energy necessary to fuel their metabo ...

to synthesize

carbohydrate A carbohydrate () is a biomolecule composed of carbon (C), hydrogen (H), and oxygen (O) atoms. The typical hydrogen-to-oxygen atomic ratio is 2:1, analogous to that of water, and is represented by the empirical formula (where ''m'' and ''n'' ...

s. The cell walls of the algae contain deposits of

calcium carbonate Calcium carbonate is a chemical compound with the chemical formula . It is a common substance found in Rock (geology), rocks as the minerals calcite and aragonite, most notably in chalk and limestone, eggshells, gastropod shells, shellfish skel ...

which give it its firm consistency. The

thallus Thallus (: 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. A thallus usually names the entir ...

of ''Spongites yendoi'' is relatively thin and is mainly composed of filaments of small, squarish

cells Cell most often refers to: * Cell (biology), the functional basic unit of life * Cellphone, a phone connected to a cellular network * Clandestine cell, a penetration-resistant form of a secret or outlawed organization * Electrochemical cell, a d ...

. The lowermost layer is up to eight thick filaments; these cells are mostly elongate. The cells are often fused. The tetrasporangial

conceptacle Conceptacles are specialized cavities of marine and freshwater algae that contain the reproductive organs. They are situated in the receptacle and open by a small ostiole.Boney, A.D. (1969). ''A Biology of Marine Algae''. Hutchinson Educational ...

s are elliptical and have a single pore. Old conceptacles do not become buried as the thallus grows. The colour varies but may be some shade of grey or chalky white. Its range in South Africa extends further north than that of the pear limpet ''

Scutellastra cochlear ''Scutellastra cochlear'' is a species of sea snail, a marine gastropod mollusc in the family Patellidae, one of the families of true limpets. It is commonly known as the snail patella, the pear limpet or the spoon limpet and is native to Sout ...

'' and when ungrazed by this limpet it is thicker and more knobbly.

Distribution and habitat

''Spongites yendoi'' is found in the southeastern Atlantic and the Indo-Pacific. Its range includes South Africa, Réunion, the Comoroes, Mayotte and Mauritius, and extends to China, Indonesia and Australia. It is also found on the coasts of the North, South and Chatham Islands of New Zealand. It grows on rocks and

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". ...

organisms in the lower parts of the

intertidal zone The intertidal zone or foreshore is the area above water level at low tide and underwater at high tide; in other words, it is the part of the littoral zone within the tidal range. This area can include several types of habitats with various ...

Ecology

On the rocky coasts of South Africa, ''Spongites yendoi'' is the main algal component of a community of organisms commonly found in the low intertidal zone. A thin layer of this alga tends to cover rock surfaces and seaweeds grow as

epiphyte An epiphyte is a plant or plant-like organism that grows on the surface of another plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphyt ...

s on top. Both the coralline alga and the seaweeds are grazed by the pear limpet and other

herbivore A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat ...

s. Twice a year, ''Spongites yendoi'' sloughs off its upper layers but nevertheless seaweeds soon grow again on the exposed surface which is usually kept clean by the feeding activities of the herbivores. Sloughing is probably a means of eliminating old reproductive structures and damaged surface cells, and reducing the risk of surface penetration by burrowing organisms. The relationship between the pear limpet and ''Spongites yendoi'' could be considered a form of mutualism. The limpet gets 85% of its nutritional needs by grazing on the coralline alga and leaves it in thin sheets with a damaged surface. The limpet is not present in the north of its range and in these areas the algal sheets are much thicker and flabbier, and develop protuberances. It has been observed that the thin form of the alga grows laterally five times as fast as the thick form and is less likely to be attacked by burrowing organisms, so the association between the two organisms may be mutually beneficial. The pear limpet tends to be covered with a marine lichen '' Pyrenocollema'' spp., and ''Spongites yendoi'' often grows on top of this. It also grows on the shells of '' Scutellastra argenvillei'', '' Patella granatina'', '' Oxystele sinensis'' and ''

Turbo In an internal combustion engine, a turbocharger (also known as a turbo or a turbosupercharger) is a forced induction device that is powered by the flow of exhaust gases. It uses this energy to compress the intake air, forcing more air into the ...

'' spp., and around the colonial mollusc '' Dendropoma corallinaceum''. A thin layer of this alga may also line tidal pools higher up the shore.

References

{{Taxonbar, from=Q10373799 Corallinaceae