Phyllodesmium
Encyclopedia
Phyllodesmium is a genus of predatory sea slugs, aeolid nudibranch
s, marine gastropod mollusks in the family Facelinidae
. These nudibranchs occur in the tropical Indo-Pacific
Oceans.
The nudibranchs in this genus often show extraordinary mimicry, each species very closely resembling its prey species, which are octocorals, a kind of soft coral.
They are also unusual in that they are able to utilize zooxanthellae from their prey, in a symbiotic relationship that provides them with extra nutrition from photosynthesis
, hence they are one of only two groups of "solar-powered" sea slugs" (also see the Sacoglossa
).
Species of the genus Phyllodesmium are carnivorous and feed on octocorals (for example in the family Xeniidae
). This is a unique feature within the Aeolidida
.
Some of these nudibranchs contain endosymbiotic zooxanthellae, which are in effect single-celled plants. Zooxanthellae are one kind of dinoflagellate
protist
s and they live only within other organisms, most notably in corals. The nudibranchs in this genus obtain zooxanthellae from their food, the soft corals.
As they previously did within the corals, the zooxanthellae provide the nudibranch with a supply of food in the form of the products of photosynthesis
. The nudibranchs are able to avoid digesting these protists, and sequester them in their tissues instead. This process is somewhat reminiscent of the relationship between the Sacoglossa
n sea slugs and the living chloroplasts that they are able to sequester. Both these nudibranchs and the sacoglossans have been referred to as "solar-powered sea slugs".
Many other species of nudibranchs are brilliantly colored in order to warn away would-be predators, that is, they have aposematic coloring. This is because they contain in their tissues many examples of an organ called the cnidosac which contains undischarged cnidocytes (also known as nematocysts). These are stinging cells that the nudibranchs obtain from the tissues of the cnidaria
ns they eat. Thus the very brightly colored nudibranchs are quite unpalatabe for predators. Some nudibranchs, such as Glaucus atlanticus
, are even capable of stinging humans very painfully.
The nudibranchs in this genus, however, use an opposite tactic. They do not have cnidosacs, and thus they would in reality be palatable to eat for various predators, however they are almost all extremely well camouflaged, so that they resemble almost perfectly the soft coral on which they live and feed, not only in color but also in form. The shape and form of the cerata of the nudibranch in each individual species resembles very closely the tentacles of the species of soft coral polyp on which that species feeds. This excellent camouflage also makes these nudibranchs difficult for humans to notice, and it is likely that a number of species in this genus have not yet been discovered, described and named scientifically.
Another tactic these nudibranchs use to protect themselves is that when threatened by a predator, they can drop one or more of their cerata
. These organs will wiggle for some time after being cast off, hopefully distracting a predator away from the animal itself. This is an example of a defensive technique known as autotomy
.
Molecular phylogeny
study of Phyllodesmium by Moore & Gosliner (2010) showed, that non-symbiotic species of Phyllodesmium evolved separately from symbiotic species of Phyllodesmium. But there is one exception: Phyllodesmium karenae have evolved in symbiotic clade and it subsequently lost its zooxanthellae.
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...
s, marine gastropod mollusks in the family Facelinidae
Facelinidae
Facelinidae is a taxonomic family of colorful sea slugs. These are specifically aeolid nudibranchs. They are marine gastropod molluscs.- 2005 taxonomy :...
. These nudibranchs occur in the tropical Indo-Pacific
Indo-Pacific
The Indo-Pacific is a biogeographic region of the Earth's seas, comprising the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the seas connecting the two in the general area of Indonesia...
Oceans.
The nudibranchs in this genus often show extraordinary mimicry, each species very closely resembling its prey species, which are octocorals, a kind of soft coral.
They are also unusual in that they are able to utilize zooxanthellae from their prey, in a symbiotic relationship that provides them with extra nutrition 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...
, hence they are one of only two groups of "solar-powered" sea slugs" (also see the Sacoglossa
Sacoglossa
Sacoglossa, commonly known as the sacoglossans or the "sap-sucking sea slugs", are a clade of small sea slugs and sea snails, marine gastropod mollusks that belong to the clade Heterobranchia...
).
Species
Species within the genus Phyllodesmium include:- Phyllodesmium briareumPhyllodesmium briareumPhyllodesmium briareum is a species of sea slug, an aolid nudibranch, a marine gastropod mollusk in the family Facelinidae.- Distribution :The distribution of Phyllodesmium briareum includes Indo-Pacific and Australia.- Description :...
(Bergh, 1896) - Phyllodesmium colemaniPhyllodesmium colemaniPhyllodesmium colemani is a species of small sea slug, an aolid nudibranch, a marine gastropod mollusk in the family Facelinidae....
Rudman, 1991 - Phyllodesmium crypticumPhyllodesmium crypticumPhyllodesmium crypticum is a species of sea slug, an aolid nudibranch, a marine gastropod mollusk in the family Facelinidae....
Rudman, 1981 - Phyllodesmium guamensisPhyllodesmium guamensisPhyllodesmium guamensis is a species of sea slug, an aolid nudibranch, a marine gastropod mollusk in the family Facelinidae.The specific name guamensis refer to Guam, its type locality.- Description :The length of the slug is 8-48 mm....
Avila, Ballesteros, Slattery, Starmer & Paul, 1998 - Phyllodesmium horridum (Macnae, 1954)
- Phyllodesmium hyalinumPhyllodesmium hyalinumPhyllodesmium hyalinum is a species of sea slug, an aolid nudibranch, a marine gastropod mollusk in the family Facelinidae.Phyllodesmium hyalinum is the type species of the genus Phyllodesmium.- Distribution :...
(Ehrenberg, 1831) - type species - Phyllodesmium iriomotensePhyllodesmium iriomotensePhyllodesmium iriomotense is a species of sea slug, an aolid nudibranch, a marine gastropod mollusk in the family Facelinidae.The specific name iriomotense refres to its type locality, the island Iriomote.- Distribution :...
Baba, 1991 - Phyllodesmium jakobsenaePhyllodesmium jakobsenaePhyllodesmium jakobsenae is a species of sea slug, an aolid nudibranch, a marine gastropod mollusk in the family Facelinidae.The specific name jakobsenae is in honor of diver and donator of marine slugs research Mrs...
Burghardt & Wägele, 2004 - Phyllodesmium kabiranumPhyllodesmium kabiranumPhyllodesmium kabiranum is a species of sea slug, an aolid nudibranch, a marine gastropod mollusk in the family Facelinidae.- Distribution :The distribution of Phyllodesmium kabiranum includes Japan. The type locality is Ishigaki, Okinawa, Japan....
Baba, 1991 - Phyllodesmium karenae Moore & Gosliner, 2009
- Phyllodesmium koehleri Burghardt, Schrödl & Wägele, 2008
- Phyllodesmium lembehensis Burghardt, Schrödl & Wägele, 2008
- Phyllodesmium lizardensis Burghardt, Schrödl & Wägele, 2008
- Phyllodesmium longicirrumPhyllodesmium longicirrumPhyllodesmium longicirrum is a species of sea slug, an aeolid nudibranch, a marine gastropod mollusk in the family Facelinidae.- Distribution :The distribution of Phyllodesmium longicirrum includes Australia and Indonesia.- Ecology :...
(Bergh, 1905) - Phyllodesmium macphersonaePhyllodesmium macphersonaePhyllodesmium macphersonae is a species of sea slug, an aolid nudibranch, a marine gastropod mollusk in the family Facelinidae.- Distribution :The distribution of Phyllodesmium macphersonae includes Australia, Tanzania and Japan....
(Burn, 1962) - Phyllodesmium magnumPhyllodesmium magnumPhyllodesmium magnum is a species of sea slug, an aolid nudibranch, a marine gastropod mollusk in the family Facelinidae.- Distribution :...
Rudman, 1991 - Phyllodesmium opalescensPhyllodesmium opalescensPhyllodesmium opalescens is a species of small sea slug, an aolid nudibranch, a marine gastropod mollusk in the family Facelinidae....
Rudman, 1991 - Phyllodesmium orientalePhyllodesmium orientalePhyllodesmium orientale is a species of small sea slug, an aolid nudibranch, a marine gastropod mollusk in the family Facelinidae.- Distribution :...
Baba, 1991 - Phyllodesmium parangatumPhyllodesmium parangatumPhyllodesmium parangatum is a species of small sea slug, an aolid nudibranch, a marine gastropod mollusk in the family Facelinidae.The specific name parangatum refers to words "parang gatas" from Filipino language, that points to its milky color...
Ortiz & Gosliner, 2003 - Phyllodesmium pectenPhyllodesmium pectenPhyllodesmium pecten is a species of small sea slug, an aolid nudibranch, a marine gastropod mollusk in the family Facelinidae.- Description :The length of the slug is 4-22 mm.This species contains zooxanthellae....
Rudman, 1981 - Phyllodesmium pinnatum Moore & Gosliner, 2009
- Phyllodesmium poindimieiPhyllodesmium poindimieiPhyllodesmium poindimiei is a species of sea slug, an aolid nudibranch, a marine gastropod mollusk in the family Facelinidae.- Distribution :The distribution of Phyllodesmium rudmani includes Australia, New Caledonia and Hawaii.- Ecology :...
(Risbec, 1928) - Phyllodesmium rudmaniPhyllodesmium rudmaniPhyllodesmium rudmani is a species of sea slug, an aolid nudibranch, a marine gastropod mollusk in the family Facelinidae.The specific name rudmani is in honor of malacologist William B...
Burghardt & Gosliner, 2006 - Phyllodesmium serratumPhyllodesmium serratumPhyllodesmium serratum is a species of sea slug, an aolid nudibranch, a marine gastropod mollusk in the family Facelinidae.- Distribution :The distribution of Phyllodesmium serratum includes Australia, Japan, Tanzania and South Africa....
(Baba, 1949) - Phyllodesmium tuberculatum Moore & Gosliner, 2009
Ecology
Xeniidae
The Xeniidae are a family of coral in the order Alcyonacea. The genus Phyllodesmium of predatory sea slugs is reported to feed on xeniidae species....
). This is a unique feature within the Aeolidida
Aeolidida
The Aeolidida is a taxonomic clade of sea slugs, specifically aeolid nudibranchs, marine gastropod molluscs in the clade Cladobranchia.-Taxonomy:*Superfamily Flabellinoidea Bergh, 1889**Family Flabellinidae**Family Notaeolidiidae...
.
Some of these nudibranchs contain endosymbiotic zooxanthellae, which are in effect single-celled plants. Zooxanthellae are one kind of 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...
protist
Protist
Protists are a diverse group of eukaryotic microorganisms. Historically, protists were treated as the kingdom Protista, which includes mostly unicellular organisms that do not fit into the other kingdoms, but this group is contested in modern taxonomy...
s and they live only within other organisms, most notably in corals. The nudibranchs in this genus obtain zooxanthellae from their food, the soft corals.
As they previously did within the corals, the zooxanthellae provide the nudibranch with a supply of food in the form of the products of 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...
. The nudibranchs are able to avoid digesting these protists, and sequester them in their tissues instead. This process is somewhat reminiscent of the relationship between the Sacoglossa
Sacoglossa
Sacoglossa, commonly known as the sacoglossans or the "sap-sucking sea slugs", are a clade of small sea slugs and sea snails, marine gastropod mollusks that belong to the clade Heterobranchia...
n sea slugs and the living chloroplasts that they are able to sequester. Both these nudibranchs and the sacoglossans have been referred to as "solar-powered sea slugs".
Many other species of nudibranchs are brilliantly colored in order to warn away would-be predators, that is, they have aposematic coloring. This is because they contain in their tissues many examples of an organ called the cnidosac which contains undischarged cnidocytes (also known as nematocysts). These are stinging cells that the nudibranchs obtain from the tissues of the cnidaria
Cnidaria
Cnidaria is a phylum containing over 9,000 species of animals found exclusively in aquatic and mostly marine environments. Their distinguishing feature is cnidocytes, specialized cells that they use mainly for capturing prey. Their bodies consist of mesoglea, a non-living jelly-like substance,...
ns they eat. Thus the very brightly colored nudibranchs are quite unpalatabe for predators. Some nudibranchs, such as Glaucus atlanticus
Glaucus atlanticus
Glaucus atlanticus is a species of small-sized blue sea slug, a pelagic aeolid nudibranch, a marine gastropod mollusk in the family Glaucidae...
, are even capable of stinging humans very painfully.
The nudibranchs in this genus, however, use an opposite tactic. They do not have cnidosacs, and thus they would in reality be palatable to eat for various predators, however they are almost all extremely well camouflaged, so that they resemble almost perfectly the soft coral on which they live and feed, not only in color but also in form. The shape and form of the cerata of the nudibranch in each individual species resembles very closely the tentacles of the species of soft coral polyp on which that species feeds. This excellent camouflage also makes these nudibranchs difficult for humans to notice, and it is likely that a number of species in this genus have not yet been discovered, described and named scientifically.
Another tactic these nudibranchs use to protect themselves is that when threatened by a predator, they can drop one or more of their cerata
Cerata
Cerata are anatomical structures found in nudibranch sea slugs, marine opisthobranch gastropod mollusks.They are dorsal and lateral outgrowths on the upper surfaces of the body....
. These organs will wiggle for some time after being cast off, hopefully distracting a predator away from the animal itself. This is an example of a defensive technique known as autotomy
Autotomy
Autotomy or self amputation is the act whereby an animal severs one or more of its own appendages, usually as a self-defense mechanism designed to elude a predator's grasp...
.
Molecular phylogeny
Molecular phylogeny
Molecular phylogenetics is the analysis of hereditary molecular differences, mainly in DNA sequences, to gain information on an organism's evolutionary relationships. The result of a molecular phylogenetic analysis is expressed in a phylogenetic tree...
study of Phyllodesmium by Moore & Gosliner (2010) showed, that non-symbiotic species of Phyllodesmium evolved separately from symbiotic species of Phyllodesmium. But there is one exception: Phyllodesmium karenae have evolved in symbiotic clade and it subsequently lost its zooxanthellae.