Symbion pandora
Encyclopedia
Symbion pandora is a jug-shaped microscopic aquatic animal that dwells on the mouth-parts of Norway lobster
s.
The animals are less than ½ mm wide, with sac-like bodies, and three distinctly different forms in different parts of their two-stage life-cycle.
. The phylum Cycliophora, from the Greek
for 'carrying a small wheel', was named after the creature's circular mouth. Two other members of that phylum have since been discovered.
Symbion refers to the animal's symbiotic relationship with its lobster host while the specific epithet pandora refers to the part of the organism's life cycle that reminded Funch and Reinhardt of the mythical Pandora's box
.
. There are three basic life stages:
by budding
and sexually
. In sexual reproduction the male attaches to a feeding stage and impregnates a budding female. The female then separates from the feeding stage and attaches herself to another host, where the larva in her develops. The female dies, and the larva escapes. The sexual reproductive cycle is triggered when the host crustacean molts its skin in order to grow.
Norway lobster
Nephrops norvegicus, known variously as the Norway lobster, Dublin Bay prawn, or scampi, is a slim, orange-pink lobster which grows up to long, and is "the most important commercial crustacean in Europe"...
s.
The animals are less than ½ mm wide, with sac-like bodies, and three distinctly different forms in different parts of their two-stage life-cycle.
Classification and naming
They are so unlike any known animal that its discovery by Danish scientists in 1995 led to the creation of a new phylumPhylum
In biology, a phylum The term was coined by Georges Cuvier from Greek φῦλον phylon, "race, stock," related to φυλή phyle, "tribe, clan." is a taxonomic rank below kingdom and above class. "Phylum" is equivalent to the botanical term division....
. The phylum Cycliophora, from the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
for 'carrying a small wheel', was named after the creature's circular mouth. Two other members of that phylum have since been discovered.
Symbion refers to the animal's symbiotic relationship with its lobster host while the specific epithet pandora refers to the part of the organism's life cycle that reminded Funch and Reinhardt of the mythical Pandora's box
Pandora's box
Pandora's box is an artifact in Greek mythology, taken from the myth of Pandora's creation around line 60 of Hesiod's Works and Days. The "box" was actually a large jar given to Pandora , which contained all the evils of the world. When Pandora opened the jar, all its contents except for one item...
.
Physical description
Symbion pandora has a bilateral, sac-like body with no coelomBody cavity
By the broadest definition, a body cavity is any fluid-filled space in a multicellular organism. However, the term usually refers to the space located between an animal’s outer covering and the outer lining of the gut cavity, where internal organs develop...
. There are three basic life stages:
- Asexual feeding stage – At this stage, S. pandora is neither male nor female. It has a length of 347 μmMicrometreA micrometer , is by definition 1×10-6 of a meter .In plain English, it means one-millionth of a meter . Its unit symbol in the International System of Units is μm...
and a width of 113 μm. On the posterior end of the sac-like body is a stalk with an adhesive disc, which attaches itself to the host. On the anterior end is a ciliated funnel (mouth) and an anus. - Sexual stage
- Female – S. pandora is the same size as the male in this stage. It does, however, have a digestive system which collapses and reconstitutes itself as a larvaLarvaA larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
. - Male – S. pandora has a length of 84 μm and a width of 42 μm during this stage. It has no mouth or anus, which signifies the absence of a digestive system. It also has two reproductive organs.
- Female – S. pandora is the same size as the male in this stage. It does, however, have a digestive system which collapses and reconstitutes itself as a larva
Reproduction
Symbion pandora can reproduce both asexuallyAsexual reproduction
Asexual reproduction is a mode of reproduction by which offspring arise from a single parent, and inherit the genes of that parent only, it is reproduction which does not involve meiosis, ploidy reduction, or fertilization. A more stringent definition is agamogenesis which is reproduction without...
by budding
Budding
Budding is a form of asexual reproduction in which a new organism grows on another one. The new organism remains attached as it grows, separating from the parent organism only when it is mature. Since the reproduction is asexual, the newly created organism is a clone and is genetically identical...
and sexually
Sexual reproduction
Sexual reproduction is the creation of a new organism by combining the genetic material of two organisms. There are two main processes during sexual reproduction; they are: meiosis, involving the halving of the number of chromosomes; and fertilization, involving the fusion of two gametes and the...
. In sexual reproduction the male attaches to a feeding stage and impregnates a budding female. The female then separates from the feeding stage and attaches herself to another host, where the larva in her develops. The female dies, and the larva escapes. The sexual reproductive cycle is triggered when the host crustacean molts its skin in order to grow.