Phylum Cycliophora
- Microscopic marine invertebrates
- Possible 3 species are known
- Discovered recently in 1995 by Danish scientists Reinhardt Kristensen and Peter Funch
- Kristensen credited for discovery of other phylums, Loricifera (1983) and Micrognathozoa (2000)
General Body Form
• Multicellular
• Bilateral Symmetry
• Acoelomate
• Protostomes
• Microscopic • Only hundreds of micrometers in length
General Body Form
• Mircovillous cellular epidermis
• Well defined cuticle
– Secreted by epidermis
• Individual muscles, not sheaths
• Brain
– Location unknown
– Nervous system not well understood
• Found living commensally on the setae of the mouth parts of lobsters.
• Found on maxillae and maxillipeds
• Mouthparts can have thousands of individuals
• Filter feed on the leftovers of host.
• Symbion pandora found on Norway lobster (Nephrops norvegicus)
• Symbion americanus found on the American lobster (Homarus
americanus)
-Commercially important species of lobster
• Not presently described species found on the European lobster (Homarus gammarus)
European Lobster
Multiple Life Stages
• Feeding Sessile Stage
– Asexual or sexual
• Multiple Motile Larval stages
– Pandora larva
– Chordoid larva
– Prometheus larva
Feeding Sessile Stage
• Circular buccal funnel
-Ciliated for feeding on bacteria and food particles.
• U-shaped Gut• Anus located outside of feed apparatus
• Attaches to mouthparts with adhesive disc and stalk
Asexual Inner Budding
• Loses buccal funnel and digestive tract
• New bud arises from embryonic cells producing only a new buccal funnel and digestive tract
• Process repeated multiple times
Asexual Reproduction
• Pandora larva is formed much the same way as asexual inner budding
• Free-swimming larva settle close to parent individual to form new feeding stage.
– Allows for quick replication over mouthparts
Sexual Reproduction
• Primary male (Prometheus larva) or female housed inside the body of the feeding stage.
• Primary male hatches and settles on a feeding stage.
• Primary male lacks penis or testis therefore forms secondary male itself with penis and spermatozoa.
Sexual Reproduction
• Secondary male swims to another feeding stage with female.
• Fertilization occurs inside female with oocyte.
• Female releases from feeding stage and settles close by.
Sexual Reproduction
• Chordoid larva forms inside settled female.
– Chordoid larva has stacked muscle cells
• Larva ingests entire female and hatches
– Good swimmer
• Represents dispersal stage
• Larva settles on new host and forms a new feeding stage.
• Funch, Peter and R. Kristensen. Symbion pandora. 1995. Photograph. Web. 01 May 2011. http://128.128.175.117/pages/1922
• Funch, P., and Kristensen, R. M. 1995. Cycliophora is a new phlum with affinities to Entoprocta and Ectoprocta. Nature 378: 711-714.
• Hansen, Asbjørn. European Lobster. 2005. Photograph. Web. 01 May 2011. http://www.flickr.com/photos/xoto/57297523/
• Reinhardt Møbjerg Kristensen. 2002 . An Introduction to Loricifera, Cycliophora, and Micrognathozoa Integr. Comp. Biol. 42(3): 641-651 doi:10.1093/icb/42.3.641
• Ruppert, Edward E., and Robert D. Barnes. Invertebrate Zoology. 7th ed. Brooks/Cole Cengage Learning, 2003. 812-15. Print.
Bibliography
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