''Actinia bermudensis'', the red, maroon or stinging anemone, 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), ...

sea anemone Sea anemones ( ) are a group of predation, predatory marine invertebrates constituting the order (biology), order Actiniaria. Because of their colourful appearance, they are named after the ''Anemone'', a terrestrial flowering plant. Sea anemone ...

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 ...

Actiniidae Actiniidae is the largest family (biology), family of sea anemones, to which most common, temperate, shore species belong. Most members of this family do not participate in symbiosis, symbioses with fishes. Three exceptions are the bubble-tip an ...

Description

''Actinia bermudensis'' attaches itself to a rock surface by its

pedal disc The pedal disc (also known as a basal plate) is the surface opposite to the mouth of the sea anemone. It serves to attach the anemone to the substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in whic ...

, which can reach 4 centimetres in width. The column is narrower at the top than the base and can reach 5 centimetres in height. Near the top is a ring of bulges called acrorhagi which contain many

cnidocyte A cnidocyte (also known as a cnidoblast) is a type of cell containing a large secretory organelle called a ''cnidocyst'', that can deliver a sting to other organisms as a way to capture prey and defend against predators. A cnidocyte explosively ...

s. The oral disc has a central mouth and two irregular whorls of 96 to 140 short, retractable, tapering

tentacle In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work main ...

s which are armed with cnidocytes. The general colour of the anemone is dark red or maroon.

Distribution and habitat

''Actinia bermudensis'' occurs in the

West Indies The West Indies is an island subregion of the Americas, surrounded by the Atlantic Ocean, North Atlantic Ocean and the Caribbean Sea, which comprises 13 independent island country, island countries and 19 dependent territory, dependencies in thr ...

Bermuda Bermuda is a British Overseas Territories, British Overseas Territory in the Atlantic Ocean, North Atlantic Ocean. The closest land outside the territory is in the American state of North Carolina, about to the west-northwest. Bermuda is an ...

and northern

Florida Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...

, Greece, Caribian pool, west Atlantica and there is a further, isolated population off

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

. It is found in the

intertidal 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 sp ...

and the

sublittoral 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 ...

. It is usually found near the base of rock walls, under overhangs, in caves, in crevices and under boulders.Red Anemone (Actinia bermudensis)
Marine Invertebrates of Bermuda. Retrieved 2011-12-11.

Biology

The acrorhagi of ''Actinia bermudensis'' are used to discourage other individuals from moving into the anemone's territory. Intruding anemones are not normally killed but usually retire to a safer place. ''Actinia bermudensis'' is an

omnivore An omnivore () is an animal that regularly consumes significant quantities of both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize t ...

. The main items of

prey Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not ki ...

are

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

isopods Isopoda is an Order (biology), order of crustaceans. Members of this group are called isopods and include both Aquatic animal, aquatic species and Terrestrial animal, terrestrial species such as woodlice. All have rigid, segmented exoskeletons ...

and small

bivalves Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed by a calcified exoskeleton consis ...

. Other food items may include other marine

invertebrate Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordata, chordate s ...

s and

algae Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...

. Many sea anemones form a

symbiotic Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term biolo ...

relationship with

zooxanthella Zooxanthellae (; zooxanthella) is a colloquial term for single-celled photosynthetic organisms that are able to live in symbiosis with diverse marine invertebrates including corals, jellyfish, demosponges, and nudibranchs. Most known zooxanthell ...

e. ''Actinia bermudensis'' often contains these

flagellate A flagellate is a cell or organism with one or more whip-like appendages called flagella. The word ''flagellate'' also describes a particular construction (or level of organization) characteristic of many prokaryotes and eukaryotes and the ...

protozoa Protozoa (: protozoan or protozoon; alternative plural: protozoans) are a polyphyletic group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic debris. Historically ...

living within its tissues but they are of a non-photosynthetic species. It is doubtful whether this should be called symbiosis as the anemone does not seem to derive any benefit from the arrangement. At times of food scarcity, however, the anemone may consume the zooxanthellae. Reproduction can take place by fission, the anemone

splitting Splitting may refer to: * Splitting (psychology) * Lumpers and splitters, in classification or taxonomy * Wood splitting * Tongue splitting * Splitting (raylway), Splitting, railway operation Mathematics * Heegaard splitting * Splitting field * S ...

in half longitudinally. The offspring are

clones Clone or Clones or Cloning or Cloned or The Clone may refer to: Places * Clones, County Fermanagh, Ireland * Clones, County Monaghan, a town in Ireland * Clones railway station, Ireland Biology * Clone (B-cell), a lymphocyte clone, the massiv ...

of the parent and genetically identical. Alternatively, sexual reproduction occurs, with internal fertilisation. In this case the juvenile sea anemones are brooded by the parent in the

gastrovascular The gastrovascular cavity is the primary organ of digestion and circulation in two major animal phyla: the Coelenterates or cnidarians (including jellyfish and corals) and Platyhelminthes (flatworms). The cavity may be extensively branched into a ...

cavity until they have grown sufficiently large to be liberated into the water column. There are ten times as many females among these brooded young as there are males. Another method of reproduction is a form of

parthenogenesis Parthenogenesis (; from the Greek + ) is a natural form of asexual reproduction in which the embryo develops directly from an egg without need for fertilization. In animals, parthenogenesis means the development of an embryo from an unfertiliz ...

with the young being brooded internally.

References

{{Taxonbar, from=Q1826010 Actiniidae Animals described in 1889