Epiactis prolifera
Encyclopedia
Epiactis prolifera, the brooding, proliferating or small green anemone, is a species
of marine invertebrate in the family
Actiniidae
. It is found in the north-eastern Pacific and is believed to be unique among animals in that all individuals start life as females but develop testes later in their lives to become hermaphrodite
s.
s each tipped with a terminal pore.
. The highest density is on or under rocks in the sublittoral
zone, in surge channels, on rock shelves and areas exposed to wave action. It is often found in areas encrusted with coralline algae
and sometimes grows on the leaves of eelgrass
. It cannot tolerate exposure to the drying air and sunlight. The brooding anemone moves around over the substrate
to a greater extent than do other anemones.
. The larvae develop tentacles of their own and grow in this protective environment for at least three months. When they reach about four millimetres in diameter, they separate from their mother and move away to live independently.
If the anemone is damaged and broken in pieces, the various fragments are each able to grow into a new individual.
The diet consists of small fish
, shrimp
s, crab
s and jellyfish
. The prey is immobilised by the nematocysts
in the tentacles which inject toxins, then passed by the tentacles through the mouth and into the gastrovascular cavity. Any undigested remains are expelled through the mouth.
s seem to be immune to the toxin and both eat them and can store the unused nematocysts for their own defence. Predators include the nudibranch Aeolidia papillosa
, the leather star Dermasterias imbricata
and certain fish.
This anemone sometimes displays mutualism
by attaching itself to a hermit crab
or decorator crab. The anemone provides protection for the host from predators
and itself benefits by being able to consume food fragments discarded by the crab.
The copepod
, Doridicola sunnivae, is an ectoparasite of the brooding anemone.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of marine invertebrate in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Actiniidae
Actiniidae
The Actiniidae is the largest family of sea anemones, to which most common, temperate, shore species belong. Most members of this family do not participate in symbioses with fishes. One exception is the so-called bubble anemone - Entacmaea quadricolor....
. It is found in the north-eastern Pacific and is believed to be unique among animals in that all individuals start life as females but develop testes later in their lives to become hermaphrodite
Hermaphrodite
In biology, a hermaphrodite is an organism that has reproductive organs normally associated with both male and female sexes.Many taxonomic groups of animals do not have separate sexes. In these groups, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which both...
s.
Description
The brooding anemone grows to three centimetres high and up to five centimetres in diameter and varies in colour, usually being greenish-brown but sometimes brown, pink, red or dull green. There are fine white lines starting at the mouth and spreading radially across the oral disc and further white lines occur on the column and pedal disc. The lower part of the column and pedal disc are occasionally blue. There are often radiating pale and dark lines on the edges of the pedal disc and the lower part of the column. The mouth is surrounded by 48 to 96 short, conical tentacleTentacle
A tentacle or bothrium is one of usually two or more elongated flexible organs present in animals, especially invertebrates. The term may also refer to the hairs of the leaves of some insectivorous plants. Usually, tentacles are used for feeding, feeling and grasping. Anatomically, they work like...
s each tipped with a terminal pore.
Distribution and habitat
The brooding anemone is found in shallow areas of the north-east Pacific OceanPacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
. The highest density is on or under rocks in the sublittoral
Neritic zone
The neritic zone, also called coastal waters, the coastal ocean or the sublittoral zone, is the part of the ocean extending from the low tide mark to the edge of the continental shelf, with a relatively shallow depth extending to about 200 meters...
zone, in surge channels, on rock shelves and areas exposed to wave action. It is often found in areas encrusted with coralline algae
Coralline algae
Coralline algae are red algae in the order Corallinales. They are characterized by a thallus that is hard because of calcareous deposits contained within the cell walls...
and sometimes grows on the leaves of eelgrass
Zostera
Zostera is a small genus of widely distributed seagrass, commonly called marine eelgrass or simply eelgrass . The genus Zostera contains sixteen species.-Ecology:Zostera is found on sandy substrates or in estuaries submerged or partially floating...
. It cannot tolerate exposure to the drying air and sunlight. The brooding anemone moves around over the substrate
Substrate (biology)
In biology a substrate is the surface a plant or animal lives upon and grows on. A substrate can include biotic or abiotic materials and animals. For example, encrusting algae that lives on a rock can be substrate for another animal that lives on top of the algae. See also substrate .-External...
to a greater extent than do other anemones.
Biology
Epiactis prolifera is a protogyny hermaphrodite. The young all start life as females but when the pedal disc is about two centimetres in diameter, they develop testes within the mesentery and spend the rest of their lives as hermaphrodites. This means that the population consists of a large number of young females and a small number of older hermaphrodites. Reproduction is not limited to any particular season. Sperm is released into the water column and after cross-fertilisation (or sometimes self-fertilisation), the young remain within the mother's gastrovascular cavity during their early development. The mother then expels a mass of eggs and mucus through her mouth and they spread across her oral disc. Cilia move some of them down the column and they become attached to the base of the column with mucusMucus
In vertebrates, mucus is a slippery secretion produced by, and covering, mucous membranes. Mucous fluid is typically produced from mucous cells found in mucous glands. Mucous cells secrete products that are rich in glycoproteins and water. Mucous fluid may also originate from mixed glands, which...
. The larvae develop tentacles of their own and grow in this protective environment for at least three months. When they reach about four millimetres in diameter, they separate from their mother and move away to live independently.
If the anemone is damaged and broken in pieces, the various fragments are each able to grow into a new individual.
The diet consists of small fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
, shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
s, crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
s and jellyfish
Jellyfish
Jellyfish are free-swimming members of the phylum Cnidaria. Medusa is another word for jellyfish, and refers to any free-swimming jellyfish stages in the phylum Cnidaria...
. The prey is immobilised by the nematocysts
Cnidocyte
A cnidocyte, cnidoblast, or nematocyte is a type of venomous cell unique to the phylum Cnidaria . The cnidocyte cell provides a means for them to catch prey and defend themselves from predators. Despite being morphologically simple, lacking a skeleton and usually being sessile, cnidarians prey on...
in the tentacles which inject toxins, then passed by the tentacles through the mouth and into the gastrovascular cavity. Any undigested remains are expelled through the mouth.
Ecology
Despite their stinging nematocysts, brooding anemones are a favoured prey for certain other animals. Many nudibranchNudibranch
A nudibranch is a member of what is now a taxonomic clade, and what was previously a suborder, of soft-bodied, marine gastropod mollusks which shed their shell after their larval stage. They are noted for their often extraordinary colors and striking forms...
s seem to be immune to the toxin and both eat them and can store the unused nematocysts for their own defence. Predators include the nudibranch Aeolidia papillosa
Aeolidia papillosa
Aeolidia papillosa is a species of sea slug, an aeolid nudibranch, a marine gastropod mollusk in the family Aeolidiidae. A. papillosa has many common names including the shaggy mouse nudibranch or the shag rug nudibranch, in part due to its shape and its numerous flattened cerata that make it look...
, the leather star Dermasterias imbricata
Dermasterias imbricata
Dermasterias imbricata or the leather star is a starfish in the family Asteropseidae. It is found at depths of up to one hundred metres off the western seaboard of North America.-Description:...
and certain fish.
This anemone sometimes displays mutualism
Mutualism
Mutualism is the way two organisms of different species biologically interact in a relationship in which each individual derives a fitness benefit . Similar interactions within a species are known as co-operation...
by attaching itself to a hermit crab
Hermit crab
Hermit crabs are decapod crustaceans of the superfamily Paguroidea. Most of the 1100 species possess an asymmetrical abdomen which is concealed in an empty gastropod shell that is carried around by the hermit crab.-Description:...
or decorator crab. The anemone provides protection for the host from predators
Predation
In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...
and itself benefits by being able to consume food fragments discarded by the crab.
The copepod
Copepod
Copepods are a group of small crustaceans found in the sea and nearly every freshwater habitat. Some species are planktonic , some are benthic , and some continental species may live in limno-terrestrial habitats and other wet terrestrial places, such as swamps, under leaf fall in wet forests,...
, Doridicola sunnivae, is an ectoparasite of the brooding anemone.