Everything about Cycliophora totally explained
Symbion is a genus of peculiar microscopic
animals, with no obvious close relatives, and which was therefore given its own
phylum, called
Cycliophora.
Symbion was discovered in
1995 by
Reinhardt Kristensen and
Peter Funch on the mouthparts of the
Norway lobster (
Nephrops norvegicus), and other, related, species have since been discovered on the
American lobster (
Homarus americanus, host to
Symbion americanus) and the
European lobster (
Homarus gammarus, host to an as yet un-named species of
Symbion). The genus is so named because of its
commensal relationship with the lobster (a form of
symbiosis) -- it feeds on the leftovers from the lobster's own feeding.
The phylogenetic position of
Symbion remains unclear: originally the phyla
Ectoprocta and
Entoprocta were considered possible relatives of
Symbion, based on structural similarities. However, genetic studies suggest that
Symbion may be more closely related to
Gnathifera.
Physical Description
Symbion pandora has a
bilateral, sac-like body with no
coelom. 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 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.
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. (Funch & Kristensen, 1995)
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.
Reproduction
Symbion can reproduce both asexually 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.
Further Information
Get more info on 'Cycliophora'.
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