Aeolidiella stephanieae
Encyclopedia
Aeolidiella stephanieae is a species
of small sea slug
, an aeolid
nudibranch
. It is a marine
gastropod mollusc in the family
Aeolidiidae
.
This is one of the most commonly sold aeolid nudibranchs in the marine aquarium
trade in North America
, because it is used to control the sea anemone
Aiptasia
.
.
of Aeolidiella stephanieae can be subdivided into 8 stages, each recognisable by characteristic morphological and behavioural features as well as specific characters of the nervous system
and the muscular system, respectively. The larval nervous system of Aeolidiella stephanieae includes an apical organ, developing central ganglia, and peripheral neurons associated with the velum
, foot and posterior, visceral part of the larva.
In Aeolidiella stephanieae the development is lecithotrophic (feed off a yolk sac). The first pair of cephalic tentacles, the rhinophore
s, emerge shortly after metamorphosis (30% of development), whereas the second pair, the oral tentacle
s, appear significantly later in postmetamorphic stages (juvenile stage, 40% of development). The same developmental pattern of cephalic tentacles has been shown in three other nudibranchs, so far (Adalaria proxima, Cadlina laevis
and Melibe leonina
). The settlement and metamorphosis in Aeolidiella stephanieae larvae are not triggered by their future prey, and most likely therefore the rhinophores develop first after metamorphosis in order to be able to locate their diet, sea anemones.
is present and the foot becomes thicker and longer, the embryo hatches shortly prior to metamorphosis. Swimming is accomplished by ciliary beats of the velar cilia.
Metamorphosis (25-30% of development): Usually one day after hatching the larvae settle on the bottom and retract into the larval shell. During the process of metamorphosis, which does not take longer than 48 hours, the animals cast off their larval shell.
The eyes indicate the anterior part of the white elongated animals. 24 hours after metamorphosis they crawl at the bottom of the culture dish without feeding. At the same time rhinophore
rudiments appear anterior to the eyes as the first pair of cephalic tentacles. Ciliation of the early juveniles is detectable all over the body. At the anterior end and on the tip of the rhinophore rudiments there are cirri, which are compound sensory
cilia. Generally, 48 hours after metamorphosis juvenile specimens of Aeolidiella stephanieae start to prey upon pieces of Aiptasia pallida anemones.
appear.
The size of the body increases one third in contrast to the previous developmental stage. As the development continues, the length and the thickness of the rhinophores and oral tentacles increases as well as the body size. At this stage additional pairs of cerata appear and on their tip the filled cnidosacs can be detected for the first time.
of Aeolidiella stephanieae is similar to that of other nudibranch
s. The larval nervous system
of Aeolidiella stephanieae includes an apical organ, developing central ganglia, and peripheral neurons associated with the velum, foot and posterior part of the larvae. The first neurons containing serotonin
and FMRFamide
are observed during the early veliger stage (5-10% of development) in the apical organ. Slightly later, in the veliger stage (15% of development), peripheral FMRFamidergic cells appear in the posterior part of the larvae, and persist throughout metamorphosis into the early juvenile stage (30% of development). In other gastropods, these neurons have never been documented to persist during metamorphosis. As in many other gastropods, the ganglia of Aeolidiella stephanieae develop from an anterior to posterior direction in both expression patterns, serotonergic and FMRFamidergic, where the cerebral ganglia develop first followed by the pedal-, and the posterior ganglia. As in other nudibranchs described, the central nervous system
of Aeolidiella stephanieae becomes more concentrated during metamorphosis. In the newly metamorphosed Aeolidiella stephanieae rhinophoral ganglia appear as additional neural structures at the same time as the rhinophores start to grow.
. However, regardless the number, larval retractor muscles make no contribution to the post-metamorphic columellar muscle in opisthobranchs.
sp., sea anemone
s that are usually considered pests in the marine aquarium hobby, because they are stressful to coral
around them, and occasionally even sting fish and desirable invertebrates. Because Aeolidiella stephanieae only eat Aiptasias, the nudibranchs will die of starvation when all the anemones are gone, so this situation must be taken into account. Prior to the description of Aeolidiella stephanieae in 2005, that species from the aquaria have been called as "Berghia verrucicornis
".
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 small sea slug
Sea slug
Sea slug is a common name used for several different groups of saltwater snails that either lack a shell or have only an internal shell, in other words this name is used for various lineages of marine gastropod mollusks that are either not conchiferous or appear not to be.The phrase "sea slug" is...
, an aeolid
Aeolidioidea
Aeolidioidea is a superfamily of small sea slugs, the aeolid nudibranchs. They are gastropod mollusks.-2005 taxonomy :The superfamily Aeolidioidea consists of the following four families :* Aeolidiidae Gray, 1827* Facelinidae Bergh, 1889* Glaucidae Gray, 1827* Piseinotecidae Edmunds, 1970Synonyms...
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...
. It is a marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
gastropod mollusc 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...
Aeolidiidae
Aeolidiidae
Aeolidiidae, the aeolid nudibranchs, are a family of Nudibranchs. Many feed on hydroids and thus have highly serrated radular teeth.- Genera :Genera and species within the Aeolidiidae include:* Aeolidia Cuvier, 1797 - type genus...
.
Distribution
The range of this species is from the most northern point 25.7°N, to the most southern 25.09°N, and from the most western 80.44°W, to the most eastern 80.2°W.This is one of the most commonly sold aeolid nudibranchs in the marine aquarium
Aquarium
An aquarium is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants...
trade in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, because it is used to control the sea anemone
Sea anemone
Sea anemones are a group of water-dwelling, predatory animals of the order Actiniaria; they are named after the anemone, a terrestrial flower. Sea anemones are classified in the phylum Cnidaria, class Anthozoa, subclass Zoantharia. Anthozoa often have large polyps that allow for digestion of larger...
Aiptasia
Aiptasia
Aiptasia is a genus of a symbiotic cnidarian belonging to the class Anthozoa . Other well known cnidarian groups include the jellyfish , the hydroids , and the box jellyfish...
.
Ecology
This sea slug lives in shallow waters from 1 to 2 m in depth. It eats anemones from the genus AiptasiaAiptasia
Aiptasia is a genus of a symbiotic cnidarian belonging to the class Anthozoa . Other well known cnidarian groups include the jellyfish , the hydroids , and the box jellyfish...
.
Life cycle
The development of Aeolidiella stephanieae lasts 60 days at 22°C. The ontogenetic developmentOntogeny
Ontogeny is the origin and the development of an organism – for example: from the fertilized egg to mature form. It covers in essence, the study of an organism's lifespan...
of Aeolidiella stephanieae can be subdivided into 8 stages, each recognisable by characteristic morphological and behavioural features as well as specific characters of the nervous system
Nervous system of gastropods
The nervous system of gastropods consists of a series of paired ganglia connected by major nerve cords, and a number of smaller branching peripheral nerves.The brain of a gastropod consists of three pairs of ganglia, all located close to the oesophagus...
and the muscular system, respectively. The larval nervous system of Aeolidiella stephanieae includes an apical organ, developing central ganglia, and peripheral neurons associated with the velum
Velum
Velum may refer to:* Superior medullary velum, part of the nervous system that stretches between parts of the brain* Veil , the veil-like membrane of immature mushrooms extending from the margin of the cap to the stem and torn by growth...
, foot and posterior, visceral part of the larva.
In Aeolidiella stephanieae the development is lecithotrophic (feed off a yolk sac). The first pair of cephalic tentacles, the rhinophore
Rhinophore
A rhinophore is one of a pair of club-shaped structures which are the most prominent part of the external head anatomy of a group of sea slugs, marine gastropod opisthobranch mollusks in the order Nudibranchia, the nudibranchs, specifically the dorid nudibranchs.- Etymology :The name relates to the...
s, emerge shortly after metamorphosis (30% of development), whereas the second pair, the oral tentacle
Tentacle
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, appear significantly later in postmetamorphic stages (juvenile stage, 40% of development). The same developmental pattern of cephalic tentacles has been shown in three other nudibranchs, so far (Adalaria proxima, Cadlina laevis
Cadlina laevis
Cadlina laevis, common name the white Atlantic cadlina, is a species of sea slug, a dorid nudibranch, a shell-less marine gastropod mollusk in the family Cadlinidae.- Distribution :...
and Melibe leonina
Melibe leonina
Melibe leonina, common names the "hooded nudibranch" or the "lion's mane nudibranch", is a species of predatory sea slug, specifically a nudibranch, a marine gastropod mollusk in the family Tethydidae.- Description :...
). The settlement and metamorphosis in Aeolidiella stephanieae larvae are not triggered by their future prey, and most likely therefore the rhinophores develop first after metamorphosis in order to be able to locate their diet, sea anemones.
Embryogenesis and larval development
| Typically the embryos of nudibranchs are enclosed by two membranes, the capsule that surrounds each embryo and another mucoid layer that encases all of the capsules in a gelatinous egg mass. After oviposition the first cleavage Cleavage (embryo) In embryology, cleavage is the division of cells in the early embryo. The zygotes of many species undergo rapid cell cycles with no significant growth, producing a cluster of cells the same size as the original zygote. The different cells derived from cleavage are called blastomeres and form a... s proceed quickly (at 1–2 hours after oviposition two-cell stage (0% of development) and at 8 hours after oviposition 16-cell stage (0.5% of development)). The divisions within an egg mass are asynchronous, both four-celled embryos and zygotes can be detected in the same egg mass. |
Early veliger stage
The first detectable structures in the early veliger stage (5-10% of development), the larval shell and the ciliated velar lobes, appear at the same time as the first movements of the larvae (rotation around their anterior-posterior axes).[File:Aeolidiella stephanieae 12.png|left|thumb|Drawing of an dorsal view of an early veliger stage larva (5% of development) showing first fibres of larval muscles:
s = shell, cap = the capsule that surrounds each embryo. The total size is about 170 μm. ]] |
Veliger stage
Veliger stage (10-20% of development): The embryo can retract the velum into the shell and the eyes as well as the larval foot (propodium) appear.[File:Aeolidiella stephanieae 13.png|left|thumb|Drawing of lateral view of veliger stage larva (10% of development) with well-developed accessory, larval, pedal (blue), and a metapodial (green) retractor muscle. The total size is about 170 μm.
o = operculum Operculum (gastropod) The operculum, meaning little lid, is a corneous or calcareous anatomical structure which exists in many groups of sea snails and freshwater snails, and also in a few groups of land snails... , s = shell.]] |
Late veliger stage and metamorphosis
Late veliger stage (20-25% of development): The operculumOperculum (gastropod)
The operculum, meaning little lid, is a corneous or calcareous anatomical structure which exists in many groups of sea snails and freshwater snails, and also in a few groups of land snails...
is present and the foot becomes thicker and longer, the embryo hatches shortly prior to metamorphosis. Swimming is accomplished by ciliary beats of the velar cilia.
| [File:Aeolidiella stephanieae 14.png|left|thumb|Drawing of lateral view of into the shell retracted metamorphic larva (25% of development) showing: - (open triangles) degenerating velar lobes and muscles,
e = eye, o = operculum, s = shell. The total size is about 120 μm.]] |
Metamorphosis (25-30% of development): Usually one day after hatching the larvae settle on the bottom and retract into the larval shell. During the process of metamorphosis, which does not take longer than 48 hours, the animals cast off their larval shell.
Early juvenile stage
Early juvenile stage (30-40% of development): Slightly after metamorphosis the early juveniles start to crawl on the bottom, which also marks the beginning of the benthic lifestyle.[File:Aeolidiella stephanieae 15.png|left|thumb|Drawing of lateral view of early juvenile stage closely after metamorphosis (30% of development) showing the body wall musculature comprises muscle fibres:
- (open triangle) larval retractor muscle is still degenerating, e = eye. The total size is about 200 μm. ]] |
The eyes indicate the anterior part of the white elongated animals. 24 hours after metamorphosis they crawl at the bottom of the culture dish without feeding. At the same time rhinophore
Rhinophore
A rhinophore is one of a pair of club-shaped structures which are the most prominent part of the external head anatomy of a group of sea slugs, marine gastropod opisthobranch mollusks in the order Nudibranchia, the nudibranchs, specifically the dorid nudibranchs.- Etymology :The name relates to the...
rudiments appear anterior to the eyes as the first pair of cephalic tentacles. Ciliation of the early juveniles is detectable all over the body. At the anterior end and on the tip of the rhinophore rudiments there are cirri, which are compound sensory
Sensory organs of gastropods
Sensory organs of gastropods include olfactory organs, eyes, statocysts and mechanoreceptors. Gastropods have no sense of hearing.- Olfactory organs :...
cilia. Generally, 48 hours after metamorphosis juvenile specimens of Aeolidiella stephanieae start to prey upon pieces of Aiptasia pallida anemones.
Juvenile stage
Juvenile stage (40-60% of development): At this stage the rudiments of oral tentacles (2nd pair of cephalic tentacles) and the paired, dorsal cerataCerata
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....
appear.
[File:Aeolidiella stephanieae 16.png|left|thumb|Drawing of dorsal view of juvenile (40% of development):
ot = the anlage of oral tentacles, r = rhinophores, c = the first cerata pairs, e = eye. The total size is about 600 μm.]] |
The size of the body increases one third in contrast to the previous developmental stage. As the development continues, the length and the thickness of the rhinophores and oral tentacles increases as well as the body size. At this stage additional pairs of cerata appear and on their tip the filled cnidosacs can be detected for the first time.
Late juvenile stage
As development proceeds, body elongation increases and more pairs of cerata as well as some tentacle-like elongation of the propodium appears.[File:Aeolidiella stephanieae 17.png|left|thumb|Drawing of dorsal view of late juvenile (65% of development) showing the meshwork of outer circular, intermediate oblique, and inner longitudinal body wall muscle fibres as well as growing tentacles and the cerata with cnidosacs. The total size is about 1400 μm.
cn = cnidosacs, ft = foot tentacle, a tentacle-like elongation of the propodium, ot = the anlage of oral tentacles, r = rhinophores, c = the first cerata pairs, e = eye.]] |
Mature stage
At the mature stage stage of Aeolidiella stephanieae, the body size is between 0.8–1 cm, which is ten times bigger than in the previous developmental stage, and the oral tentacles are twice as long as the rhinophores. Reproductive maturity is reached 60 days after oviposition (100% of development). The first egg masses are small and contain 60 to 80 embryos. Mature individuals reach a maximum size of 5 cm, and their egg masses contain 1000 to 2000 embryos.Central nervous system and periphery
The neurogenesisNeurogenesis
Neurogenesis is the process by which neurons are generated from neural stem and progenitor cells. Most active during pre-natal development, neurogenesis is responsible for populating the growing brain with neurons. Recently neurogenesis was shown to continue in several small parts of the brain of...
of Aeolidiella stephanieae is similar to that of other 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...
s. The larval nervous system
Nervous system of gastropods
The nervous system of gastropods consists of a series of paired ganglia connected by major nerve cords, and a number of smaller branching peripheral nerves.The brain of a gastropod consists of three pairs of ganglia, all located close to the oesophagus...
of Aeolidiella stephanieae includes an apical organ, developing central ganglia, and peripheral neurons associated with the velum, foot and posterior part of the larvae. The first neurons containing serotonin
Serotonin
Serotonin or 5-hydroxytryptamine is a monoamine neurotransmitter. Biochemically derived from tryptophan, serotonin is primarily found in the gastrointestinal tract, platelets, and in the central nervous system of animals including humans...
and FMRFamide
FMRFamide
FMRFamide is a neuropeptide from a broad family of FMRFamide-related peptides all sharing an -RFamide sequence at their C-terminus. First identified in Hard clam Mercenaria mercenaria it is thought to play an important role in cardiac activity regulation...
are observed during the early veliger stage (5-10% of development) in the apical organ. Slightly later, in the veliger stage (15% of development), peripheral FMRFamidergic cells appear in the posterior part of the larvae, and persist throughout metamorphosis into the early juvenile stage (30% of development). In other gastropods, these neurons have never been documented to persist during metamorphosis. As in many other gastropods, the ganglia of Aeolidiella stephanieae develop from an anterior to posterior direction in both expression patterns, serotonergic and FMRFamidergic, where the cerebral ganglia develop first followed by the pedal-, and the posterior ganglia. As in other nudibranchs described, the central nervous system
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
of Aeolidiella stephanieae becomes more concentrated during metamorphosis. In the newly metamorphosed Aeolidiella stephanieae rhinophoral ganglia appear as additional neural structures at the same time as the rhinophores start to grow.
Myogenesis
Aeolidiella stephanieae has an larval retractor muscle and also the accessory larval retractor muscle is present. As in other nudibranchs the post-metamorphic myo-anatomy in Aeolidiella stephanieae is formed de novoDe novo
In general usage, de novo is a Latin expression meaning "from the beginning," "afresh," "anew," "beginning again." It is used in:* De novo transcriptome assembly, the method of creating a transcriptome without a reference genome...
. However, regardless the number, larval retractor muscles make no contribution to the post-metamorphic columellar muscle in opisthobranchs.
In the aquarium
Aeolidiella stephanieae is considered one of the best predators for AiptasiaAiptasia
Aiptasia is a genus of a symbiotic cnidarian belonging to the class Anthozoa . Other well known cnidarian groups include the jellyfish , the hydroids , and the box jellyfish...
sp., sea anemone
Sea anemone
Sea anemones are a group of water-dwelling, predatory animals of the order Actiniaria; they are named after the anemone, a terrestrial flower. Sea anemones are classified in the phylum Cnidaria, class Anthozoa, subclass Zoantharia. Anthozoa often have large polyps that allow for digestion of larger...
s that are usually considered pests in the marine aquarium hobby, because they are stressful to coral
Coral
Corals are marine animals in class Anthozoa of phylum Cnidaria typically living in compact colonies of many identical individual "polyps". The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.A coral "head" is a colony of...
around them, and occasionally even sting fish and desirable invertebrates. Because Aeolidiella stephanieae only eat Aiptasias, the nudibranchs will die of starvation when all the anemones are gone, so this situation must be taken into account. Prior to the description of Aeolidiella stephanieae in 2005, that species from the aquaria have been called as "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...
".