By Crystal Parsons
Geographic Range
Symbion pandora can be found on the lips of Norwegian lobsters, Nephrops norvegicus. They are found at depths of 20-40 meters (66-131 feet) from coastal Norway south to the coastline of the Mediterranean region. (Burton and Burton, 1989; Morris, 14 December 1995)
Biogeographic Regions:
atlantic ocean 
(native ).
Habitat
Symbion pandora can be found on the mouth bristles of the Norwegian lobster. It attaches to the lobster with an adhesive disk located on its posterior end. Symbion pandora shares a symbiotic relationship with its host. It recieves easy access to food with out harming or helping the Norwegian lobster. This is called commensalism. (Morris, 14 December 1995)
These animals are found in the following types of habitat:
saltwater or marine .
Aquatic Biomes:
coastal .
Physical Description
Symbion pandora has a bilateral, sack-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 um and a width of 113 um. On the posterior end of the sack-like body is a stalk with an adhesive disk, which attaches itself to the host. On the anterior end is a ciliated funnel (mouth) and an anus.
Male- S. pandora has a length of 84 um and a width of 42 um 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 larva. (Funch and Kristensen, 14 December 1995)
Some key physical features:
ectothermic ; heterothermic ; bilateral symmetry .
Sexual dimorphism: sexes alike.
Reproduction
Symbion pandora reproduces both sexually and asexually. It reproduces asexually by young budding off from the asexual feeding stage. The sexual cycle begins only during the molting season of the Norwegian lobster, its host. The male attaches itself to a feeding stage that contains a developing female and impregnates her. She escapes from the feeding stage and attaches herself to the host. The larva develops within the female S. pandora She then dies and the larva escapes. (Funch and Kristensen, 14 December 1995)
Key reproductive features:
sexual ; asexual ; fertilization ; ovoviviparous .
Behavior
Symbion pandora is a solitary species. Interaction seems to be limited to mating and feeding. Symbion pandora is sessile most of its life. There are, however, three brief periods of free swimming which occur between feeding stages. (Funch and Kristensen, 14 December 1995)
Food Habits
Symbion pandora attaches itself on the lips of Norwegian lobsters, where it then sweeps food particles into its ciliated, disk-shaped mouth. The digestive system is closely intertwined with the reproductive cycle. A unique feature of the digestive system of S. pandora is that it collapses and becomes larva. (Olsen, 18 December 1995)
Foraging Behaviors:
filter-feeding .
Ecosystem Roles
This species is parasitic on Norweigan lobsters.
Key ways these animals impact their ecosystem:
parasite .
- Nephrops norvegicus
Economic Importance for Humans: Negative
Unknown at this time
Economic Importance for Humans: Positive
Unknown at this time
Conservation Status
IUCN Red List: [link]:
Not Evaluated.
US Federal List: [link]:
No special status.
CITES: [link]:
No special status.
Symbion pandora is not on vulnerable, threatened, or endangered status. In fact, large populations can be found on a single lobster. (Funch and Kristensen, 14 December 1995)
Other Comments
Symbion pandora was an important discovery for scientists in 1995. While it is not considered unusual to discover a new species, it is unusual to find a new phylum. Cycliophora, its designated phylum, was created because the digestive system and reproductive cycle are unique to the animal kingdom. There are still many unknowns concerning S. pandora. Most information on its life cycle and sexual habits are hypothetical. (Funch and Kristensen, 14 December 1995; Walker, 1995)
Contributors
Crystal Parsons (author), Fresno City College.
Carl Johansson (editor), Fresno City College.
