Crustose is a

habit A habit (or wont as a humorous and formal term) is a routine of behavior that is repeated regularly and tends to occur subconsciously.

of some types of

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

and

lichens A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among hypha, filaments of multiple fungus, fungi species in a mutualism (biology), mutualistic relationship.appressed This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary o ...

to a substrate, forming a biological layer. ''Crustose'' adheres very closely to the substrates at all points. ''Crustose'' is found on

rocks In geology, rock (or stone) is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its chemical composition, and the way in which it is formed. Rocks form the Earth's ...

and

tree bark Bark is the outermost layers of stems and roots of woody plants. Plants with bark include trees, woody vines, and shrubs. Bark refers to all the tissues outside the vascular cambium and is a nontechnical term. It overlays the wood and cons ...

. Some species of marine

of the

Rhodophyta Red algae, or Rhodophyta (, ; ), are one of the oldest groups of eukaryotic algae. The Rhodophyta also comprises one of the largest phyla of algae, containing over 7,000 currently recognized species with taxonomic revisions ongoing. The majority ...

, in particular members of the order Corallinales,

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 ...

, subfamily Melobesioideae with cell walls containing calcium carbonate grow to great depths in the intertidal zone, forming crusts on various substrates. The substrate can be rocks throughout the intertidal zone, or, as in the case of the Corallinales, reef-building

corals Corals are marine invertebrates within the class (biology), class Anthozoa of the phylum Cnidaria. They typically form compact Colony (biology), colonies of many identical individual polyp (zoology), polyps. Coral species include the important C ...

, and other living organisms including plants, such as

mangrove A mangrove is a shrub or tree that grows in coastal saline water, saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse, as a result of convergent evoluti ...

s and animals such as shelled

mollusc Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

s. The coralline red algae are major members of coral reef communities, cementing the corals together with their crusts. Among the

brown algae Brown algae (singular: alga), comprising the class Phaeophyceae, are a large group of multicellular algae, including many seaweeds located in colder waters within the Northern Hemisphere. Brown algae are the major seaweeds of the temperate and po ...

, the order

Ralfsiales Ralfsiales is an order of crustose brown algae (class Phaeophyceae) containing two families Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationshi ...

comprises two families of crustose algae.

Growth and habitat

Many

lichen A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.drought A drought is defined as drier than normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, an ...

resistant climates. Crustose lichens have been found in deserts, ice free parts of Antarctica, and in the Alpine and Arctic regions.

Characteristics

Crustose can come in a variety of colors such as yellow, orange, red, gray and green. These colors tend to be bright and vibrant. Crustose is similar to other lichens because they share a similar internal morphology. The lichen's body is formed from filaments of the fungal partner. The density of these filaments determines the layers within the lichen.

Productivity

There are many variations of crustose, including Crustose Coralline Algae (CCA), found in three different habitats; flat, crest and slope reef. CCA are highly dependent on sunlight to grow in abundance, and their growth increases productivity. CCA acts as the main food source for certain fish including parrotfish and Scarus trispinosus.

References

Red algae {{Biology-stub