- Phylum Cycliophora are microscopic marine invertebrates that were discovered in 1995 living commensally on lobster mouthparts. Only a few possible species are known. - They have a multicellular, bilateral, acoelomate body that is hundreds of micrometers in length with an epidermis, cuticle, individual muscles, and unknown nervous system. - They reproduce both asexually through budding and sexually, with multiple motile larval stages that allow settlement on new hosts.

1. 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)

2. General Body Form
• Multicellular
• Bilateral Symmetry
• Acoelomate
• Protostomes
• Microscopic
• Only hundreds of micrometers in length

3. General Body Form
• Mircovillous cellular epidermis
• Well defined cuticle
– Secreted by epidermis
• Individual muscles, not sheaths
• Brain
– Location unknown
– Nervous system not well understood

4. • Found living commensally on the setae of the mouth parts of
lobsters.
• Found on maxillae and maxillipads
• Mouthparts can have thousands of individuals
• Filter feed on the leftovers of host.
• Symbion americanus found on the American lobster -Commercially
important species of lobster
• Not presently described species found on the European lobster

5. European Lobster

6. Multiple Life Stages
• Feeding Sessile Stage
– Asexual or sexual
• Multiple Motile Larval stages
– Pandora larva
– Chordoid larva
– Prometheus larva

7. 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

9. 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

10. 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

12. 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.

13. 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.

14. 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.