Aiptasia
Encyclopedia
Aiptasia is a genus
of a symbiotic cnidarian belonging to the class Anthozoa
(sea anemones, corals). Other well known cnidarian groups include the jellyfish
(Class Scyphozoa
), the hydroids (fire coral, and the genus Hydra
), and the box jellyfish (Class Cubozoa). Aiptasia is widely distributed tropical sea anemone of benthic lifestyle typically found living on mangrove
roots and nearby hard substrates. This anemone, as well as many other cnidarian species, is found to contain symbiotic dinoflagellate
unicellular algae of the genus Symbiodinium living inside nutritive cells. The symbionts provide food mainly in the form of lipids and sugars produced from photosynthesis
to the host while the hosts provides inorganic nutrients and a constant and protective environment to the algae.
Species of Aiptasia are relatively weedy anemones able to withstand a relatively wide range of salinities and other water quality conditions. In the case of A. pallida and A. pulchella, their hardiness coupled with their ability to reproduce very quickly and out-compete other species in culture gives these anemones the status of pest from the perspective of coral reef aquarium hobbyists. Ironically, these characteristics make it easy to grow in the laboratory and thus it is extensively used as model system for scientific study. In this respect, Aiptasia has contributed a significant amount of knowledge regarding cnidarian biology, especially our understanding of cnidarian-algal symbioses, a biological phenomenon crucial to the survival of corals and coral reef
ecosystems. The dependence of coral reefs on the health of the symbiosis is dramatically illustrated by the devastating effects experienced by corals due to the loss of algal symbionts in response to environmental stress, a phenomenon known as coral bleaching
.
and the medusae. Some alternate between these two forms during their life cycle. In the case of Aiptasia, and all anthozoans, the body form is the polyp. The body is composed of a pedal disc
with which Aiptasia attaches to the substrate, a smooth and elongated body column and an oral disc which bears the mouth and long stinging tentacles.
becomes a free swimming planula
larva which eventually settles onto a suitable substrate where it undergoes metamorphosis
to become a small polyp. Newly produced larvae are aposymbiotic meaning they do not contain symbionts. The larvae or newly settled polyps can acquire symbiotic algae from the environment.
. Once present in the aquarium, the polyps are notoriously difficult to remove as attempts to remove often inadvertently create more, due to new polyps regenerating from remnants. Hobbyists commonly put Peppermint shrimp
inside the aquarium to control Aiptasia populations, as the arthropods regularly prey on small cnidarian polyps. The nudibranch
Berghia verrucicornis
is considered one of the best predators for Aiptasia sp.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of a symbiotic cnidarian belonging to the class Anthozoa
Anthozoa
Anthozoa is a class within the phylum Cnidaria that contains the sea anemones and corals. Unlike other cnidarians, anthozoans do not have a medusa stage in their development. Instead, they release sperm and eggs that form a planula, which attaches to some substrate on which the cnidarian grows...
(sea anemones, corals). Other well known cnidarian groups include the 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...
(Class Scyphozoa
Scyphozoa
Scyphozoa is a class within the phylum Cnidaria, sometimes referred to as the "true jellyfish".The class name Scyphozoa comes from the Greek word skyphos , denoting a kind of drinking cup and alluding to the cup shape of the organism....
), the hydroids (fire coral, and the genus Hydra
Hydra (genus)
Hydra is a genus of simple fresh-water animal possessing radial symmetry. Hydras are predatory animals belonging to the phylum Cnidaria and the class Hydrozoa. They can be found in most unpolluted fresh-water ponds, lakes, and streams in the temperate and tropical regions and can be found by...
), and the box jellyfish (Class Cubozoa). Aiptasia is widely distributed tropical sea anemone of benthic lifestyle typically found living on mangrove
Mangrove
Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...
roots and nearby hard substrates. This anemone, as well as many other cnidarian species, is found to contain symbiotic dinoflagellate
Dinoflagellate
The dinoflagellates are a large group of flagellate protists. Most are marine plankton, but they are common in fresh water habitats as well. Their populations are distributed depending on temperature, salinity, or depth...
unicellular algae of the genus Symbiodinium living inside nutritive cells. The symbionts provide food mainly in the form of lipids and sugars produced from photosynthesis
Photosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...
to the host while the hosts provides inorganic nutrients and a constant and protective environment to the algae.
Species of Aiptasia are relatively weedy anemones able to withstand a relatively wide range of salinities and other water quality conditions. In the case of A. pallida and A. pulchella, their hardiness coupled with their ability to reproduce very quickly and out-compete other species in culture gives these anemones the status of pest from the perspective of coral reef aquarium hobbyists. Ironically, these characteristics make it easy to grow in the laboratory and thus it is extensively used as model system for scientific study. In this respect, Aiptasia has contributed a significant amount of knowledge regarding cnidarian biology, especially our understanding of cnidarian-algal symbioses, a biological phenomenon crucial to the survival of corals and coral reef
Coral reef
Coral reefs are underwater structures made from calcium carbonate secreted by corals. Coral reefs are colonies of tiny living animals found in marine waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups. The polyps...
ecosystems. The dependence of coral reefs on the health of the symbiosis is dramatically illustrated by the devastating effects experienced by corals due to the loss of algal symbionts in response to environmental stress, a phenomenon known as coral bleaching
Coral bleaching
Coral bleaching is the loss of intracellular endosymbionts through either expulsion or loss of algal pigmentation.The corals that form the structure of the great reef ecosystems of tropical seas depend upon a symbiotic relationship with unicellular flagellate protozoa, called zooxanthellae, that...
.
Morphology
Cnidarian species are found in one of two body forms: the polypPolyp
A polyp in zoology is one of two forms found in the phylum Cnidaria, the other being the medusa. Polyps are approximately cylindrical in shape and elongated at the axis of the body...
and the medusae. Some alternate between these two forms during their life cycle. In the case of Aiptasia, and all anthozoans, the body form is the polyp. The body is composed of a pedal disc
Pedal disc
The pedal disc is, in anatomy of the sea anemone, the surface opposite to the mouth, and generally serves to attach the anemone to the substrate, or hard surface, upon which it lives. It is composed of a thin tissue plate and is used by the animal to adhere to and move across the surface....
with which Aiptasia attaches to the substrate, a smooth and elongated body column and an oral disc which bears the mouth and long stinging tentacles.
Reproduction
In the case of the well-studied Aiptasia pallida and Aiptasia pulchella, individuals are dioecious, meaning that individuals are of separate sexes. During spawning, anemones release their gametes into the water where fertilization occurs. The resulting zygoteZygote
A zygote , or zygocyte, is the initial cell formed when two gamete cells are joined by means of sexual reproduction. In multicellular organisms, it is the earliest developmental stage of the embryo...
becomes a free swimming planula
Planula
A planula is the free-swimming, flattened, ciliated, bilaterally symmetric larval form of various cnidarian species. The planula forms from the fertilized egg of a medusa, as the case in scyphozoans and some hydrozoans, or from a polyp, as in the case of anthozoans...
larva which eventually settles onto a suitable substrate where it undergoes metamorphosis
Metamorphosis
Metamorphosis is a biological process by which an animal physically develops after birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation...
to become a small polyp. Newly produced larvae are aposymbiotic meaning they do not contain symbionts. The larvae or newly settled polyps can acquire symbiotic algae from the environment.
In the aquarium
Aiptasia sp. are considered pests in the marine aquarium hobby, because they are stressful to coral around them, and occasionally even sting fish and desirable invertebrates. They are often accidentally imported along with live rockLive rock
Live rock is rock from the ocean that has been introduced into a saltwater aquarium. Along with live sand, it confers to the closed marine system multiple benefits desired by the saltwater aquarium hobbyist...
. Once present in the aquarium, the polyps are notoriously difficult to remove as attempts to remove often inadvertently create more, due to new polyps regenerating from remnants. Hobbyists commonly put Peppermint shrimp
Lysmata wurdemanni
Lysmata wurdemanni, also known as the peppermint shrimp, is a species of shrimp.-Description:It reaches in length, and is named for the bright red stripes on its otherwise translucent body, which are reminiscent of peppermint candies such as a candy cane...
inside the aquarium to control Aiptasia populations, as the arthropods regularly prey on small cnidarian polyps. The nudibranch
Nudibranch
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...
Berghia verrucicornis
Berghia verrucicornis
Berghia verrucicornis is a species of marine nudibranch in the family Aeolidiidae.-Distribution:Berghia verrucicornis is an inhabitant of the North Atlantic Ocean, present in the Azores Exclusive Economic Zone, the Caribbean Sea, Costa Rica, European waters, the Gulf of Mexico, Jamaica, the...
is considered one of the best predators for Aiptasia sp.