''Millepora alcicornis'', or sea ginger, 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 colonial fire coral with a

calcareous Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime (mineral), lime or being chalky. The term is used in a wide variety of Science, scientific disciplines. In zoology ''Calcare ...

skeleton. It is found on shallow water

coral reef A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in group ...

s in the tropical west Atlantic Ocean. It shows a variety of different morphologies depending on its location. It feeds on plankton and derives part of its energy requirements from

microalgae Microalgae or microphytes are microscopic scale, microscopic algae invisible to the naked eye. They are phytoplankton typically found in freshwater and marine life, marine systems, living in both the water column and sediment. They are unicellul ...

found within its tissues. It is an important member of the reef building community and subject to the same threats as other corals. It can cause painful stings to unwary divers.

Taxonomy

''Millepora alcicornis'' is not a true

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

class Class, Classes, or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used d ...

Anthozoa Anthozoa is one of the three subphyla of Cnidaria, along with Medusozoa and Endocnidozoa. It includes Sessility (motility), sessile marine invertebrates and invertebrates of brackish water, such as sea anemones, Scleractinia, stony corals, soft c ...

but is in class

Hydrozoa Hydrozoa (hydrozoans; from Ancient Greek ('; "water") and ('; "animals")) is a taxonomy (biology), taxonomic class (biology), class of individually very small, predatory animals, some solitary and some colonial, most of which inhabit saline wat ...

, and is more closely related to

jellyfish Jellyfish, also known as sea jellies or simply jellies, are the #Life cycle, medusa-phase of certain gelatinous members of the subphylum Medusozoa, which is a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animal ...

than stony corals. Because of the variability in growth habit that this coral exhibits, it has been the subject of much confusion as to its taxonomy, being described under a number of different names from different localities. In 1898, Hickson decided that the variations in morphology were due to environmental factors and that ''Millepora alcicornis'' was the valid name for all these species. This conclusion has since been questioned. The species was first described by

Carl Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...

in his landmark 1758 10th edition of ''Systema Naturae'', but his type locality is unknown. The scientific name comes from the

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

with ''Millepora'' meaning "thousand-pored" and ''alcicornis'' meaning "

elk The elk (: ''elk'' or ''elks''; ''Cervus canadensis'') or wapiti, is the second largest species within the deer family, Cervidae, and one of the largest terrestrial mammals in its native range of North America and Central and East Asia. ...

-horned". It seems likely that the type locality is in fact the West Indies. Explaining this in 1941 Crossland wrote "I cannot resist the remark that the one thing quite certain about the many forms of ''Millepora'' is that none of them have any resemblance to an elk's horn, except perhaps that from the West Indies".

Description

The

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

of ''Millepora alcicornis'' is very variable. Most colonies probably start as encrusting forms and adopt a branching structure as they grow. The encrustations can become established on a variety of structures, not only on coral reefs and rocks but also on dead corals and the hulls of wrecked ships. Later development is in the form of plates or blades in habitats with much water movement such as the surf-pounded outer edges of reefs. In calmer waters, such as in deep lagoons or more sheltered parts of the reef, a more upright, leafy or branched structure develops which can grow to tall. The habit of growth is also influenced by the inclination of the surface on which the fire coral grows. On vertical surfaces, the encrusting bases are larger with longer perimeters and the density of branching is lower than it is on horizontal surfaces. The cylindrical branches usually grow in a single plane and span a range of hues from brown to pale, cream-like yellow, while branch tips are white.Fire Coral (''Millepora alcicornis'')
Marine Invertebrates of Bermuda. Retrieved 2012-01-02.Branching fire coral (''Millepora alcicornis'')
Marine Species Identification Portal. Retrieved 2012-01-03. Embedded in the calcareous skeleton are numerous microscopic polyps. They are connected internally by a system of canals and are concealed behind pores in the skeleton, the surface of which is smooth and lacks the

corallite A corallite is the skeletal cup, formed by an individual stony coral polyp, in which the polyp sits and into which it can retract. The cup is composed of aragonite, a crystalline form of calcium carbonate, and is secreted by the polyp. Corallit ...

s of true stony corals. The polyps have specialist functions, the

gastrozooid {{Short pages monitor