Pseudobiceros bedfordi

Geographic Range

Pseudobiceros bedfordi , the Persian carpet flatworm, has a very small geographic range mostly in the temperate shallow intertidal ocean waters of the Indo-West Pacific. They are rarely seen but most reports have reported sightings on the Great Barrier Reef, the coast of Guam, Papua New Guinea, Indonesia, and Australia. The species is often mentioned as a scuba diving spectacle on tourism websites for Singapore.

• Biogeographic Regions
• oriental oriental
  • native native
• australian australian
  • native native

Habitat

The habitat for Pseudobiceros bedfordi is mainly benthic and found in shallow marine habitats among rocks and crevices in a bay, lagoon or on a reef. The flatworms are most likely to be found under rubble at a reef crest or at the ledges of a reef slope. They are adapted for swimming but the majority of the time are safely hidden among rocks or other hard substrates such as reefs. These flatworms are able to swim freely by swift, flamboyant undulations of their ruffled perimeter. Therefore, although they prefer the safety of a substrate, it is possible to spot them throughout the water column.

• Habitat Regions
• saltwater or marine saltwater or marine

• Aquatic Biomes
• reef reef
• coastal coastal

• Other Habitat Features
• intertidal or littoral intertidal or littoral

Physical Description

The size of P. bedfordi ranges from 8-10 centimeters. These flatworms are very delicate creatures, having thin ribbon-like elongated or oval-shaped bodies approximately a millimeter thick with a thicker midline. They have a very flat and smooth dorsal surface and are only a few millimeters thick. The Persian carpet flatworms are often mistaken for a nudibranch due to their bright colors, but the flatworms are flatter and move quicker. The body has rich patterns of stripes in black, brown and rose pink with tiny white dots. The stripes curve from the center of the body to the sides and the edge of the body is black with white dots, usually highly ruffled. The ruffled edges are used for swimming.

Prominent pseudotentacles are formed by simple folds of the anterior margin. Different from nudibranchs , they do not have external gills or lungs, instead they can exchange gas across their entire body surface, through diffusion. A slightly ruffled pharynx is located in the anterior one-third of the body and the mouth is a large opening located at the anterior end of the pharynx. The sucker is conspicuous and centrally located. The ventral surface is a light pink and when "penis fencing" they protrude the double pronged stylet from the ventral surface. They have two male pores and one female pore, however, the female pore is not the point of insertion for insemination because insemination can take place on any part of the surface of the flatworm.

• Other Physical Features
• ectothermic ectothermic
• heterothermic heterothermic
• bilateral symmetry bilateral symmetry
• poisonous poisonous

• Sexual Dimorphism
• sexes alike

Development

The development of this species is not known but it is believed that like most flatworms they undergo metamorphosis. After ten days of development, the larva hatch and are lobed and with cilia. The larva then enter the planktonic phase and swim around for a few days before settling onto a place with a sufficient source of food; there, they metamorphose into adult benthic forms.

• Development - Life Cycle
• metamorphosis metamorphosis

Reproduction

Pseudobiceros bedfordi is hermaphroditic producing both eggs and sperm. The majority of their body volume is made of testes and ovaries. Pseudotentacles help gather chemosensory information to find a mating parter. When a mating partner is found, the two hermaphrodites have a dual or "penis fence" to see who bears the burden of motherhood which is much more energy costly. The two worms will dance and attempt to stab one another with their double-prong penis stylet. When the thin tissue of the loser is stabbed, it is immediately inseminated and the loser retreats to bear the burden of motherhood.

In polyclad worms , eggs are fertilized as they meet sperm and pass down the oviducts. While still inside the flatworm, a protective shell or capsule is formed around the eggs. The capsule surrounding the egg is hardened when released by the worm into the surrounding environment. Polyclad eggs are usually laid in thin sheets with sticky secretions.

• Key Reproductive Features
• simultaneous hermaphrodite
• fertilization fertilization
  • internal internal
• oviparous oviparous

While no parental care is provided after the worms lay their eggs, a protective capsule surrounding the egg is secreted prior to the worm's release of the eggs.

• Parental Investment
• pre-hatching/birth
  • protecting
    • female

Lifespan/Longevity

Larva in lab conditions survived for only two weeks. This species is difficult to keep alive in captivity.

Behavior

When stressed the flatworm will dissolve in its own enzymes. Because Pseudobiceros bedfordi is hermaphroditic, it is assumed that partners rarely encounter one another resulting in a solitary lifestyle. However, when they do encounter eachother, they perform a mating behavior called "penis fencing".

• Key Behaviors
• natatorial natatorial
• nocturnal nocturnal
• solitary solitary

Communication and Perception

Communication and perception of Pseudobiceros bedfordi is like other polyclad flatworms. On the head are pseudotentacles with several photosensitive and chemosensitive cells. These cells send information to the anterior cerebrial ganglion knot located on the dorsal anterior area or "head". Also, dispersed throughout the epidermis are mechanoreceptors that respond to pressure. Photosensitive cells can be found on the cerebral eyespot where numerous eyes (about 90–100) appear to form round clusters. Further eyes are located on the ventral and dorsal pseudotentacles. These eyes are sensitive to changes in light direction and intensity and form images according to shadows produced from surroundings. They sense their surroundings by changes in shadow pattern. Since these creatures are mostly nocturnal, when they sense bright light they usually retreat to a darker place such as a rock crevice. Since the flatworm has weak visual senses, it relies mostly on chemosensory detectors. Chemoreceptors on the pseudotentacles are thought be responsible for sensing food as well as mating partners. Specific chemicals that are released from food or mating partners float through the water and are then sensed by the worms chemoreceptors on their pseudotenacles. In addition to their auricles and eyespots, flatworms have primitive balance organs called statocysts, which consist of pressure sensitive hairs and small grains of material that can roll around to tell the flatworm which way is up.

• Communication Channels
• chemical chemical

• Perception Channels
• polarized light polarized light
• tactile tactile
• chemical chemical

Food Habits

Pseudobiceros bedfordi preys mainly on ascidians as well as small crustaceans. They feed like a starfish, gliding over the organism and extruding their pharynx that releases enzymes. The enzymes digest the tissue of their prey then suck the body liquids. Their prey includes tiny animals such as protozoa and worms, sessile animals such as ascidians and molluscs, and some have been observed eating shrimps and crabs.

• Primary Diet
• carnivore carnivore
  • eats non-insect arthropods
  • molluscivore molluscivore
  • eats other marine invertebrates

• Animal Foods
• body fluids
• cnidarians
• other marine invertebrates

Predation

• Anti-predator Adaptations
• aposematic aposematic

Ecosystem Roles

Little is known about the ecosystem role of this species.

Economic Importance for Humans: Positive

There are no known positive economic effects of this species on humans.

Economic Importance for Humans: Negative

There are no known negative economic effects of this species on humans.

Conservation Status

Pseudobisceros bedfordi is not listed among the threatened animals. However, they are very delicate creatures and like other creatures of the intertidal zone, flatworms are affected by human activities such as reclamation and pollution. Trampling by careless visitors, and overcollection of their food source can also have an impact on local populations.

Additional Links

Encyclopedia of Life

Contributors

Amber Morykwas (author), University of Michigan-Ann Arbor, Renee Mulcrone (editor), Special Projects.

References

Bolanos, M. 2007. Five new species of cotylean flatworms (Platyhelminthes: Polycladida) from the wider Caribbean. Zootaxa , 1650: 1-23. Accessed May 22, 2011 at http://www.mapress.com/zootaxa/2007f/zt01650p023.pdf .

Garfield, J. 2010. "sdnews.com" (On-line). Accessed May 22, 2011 at http://www.sdnews.com/view/full_story/4479639/article-For-polyclad-worm--sex-and-swordplay-synonymous?instance=LJ_home_news_bullets .

Michielis, N. 2006. "Battle of the hermaphrodites" (On-line). Accessed May 22, 2011 at http://www.biologyjunction.com/hermaphrodite_article.htm .

Newman, L., L. Cannon, A. Flowers. 2003. Marine flatworms: the world of polyclads . Collingwood, Australia: CSIRO Publishing. Accessed May 22, 2011 at http://books.google.com/books?id=pwLs5AD_C-cC&printsec=frontcover&source=gbs_v2_summary_r&cad=0#v=onepage&q=&f=false .

Newman, L., L. Cannon. 1996. Bulaceros , new genus, and Tytthosoceros , new genus, from the Great Barrier Reef, Australia and Papua New Guinea. The Raffles Bulletin of Zoology , 44/2: 479-492. Accessed May 22, 2011 at http://rmbr.nus.edu.sg/rbz/biblio/44/44rbz479-492.pdf .

Newman, L., L. Cannon. 1997. Nine new species of Pseudobiceros from the Indo-Pacific. The Raffles Bulletin of Zoology , 45/2: 341-368. Accessed May 22, 2011 at http://rmbr.nus.edu.sg/rbz/biblio/45/45rbz341-368.pdf .

Rawlinson, K. 2008. Biodiversity of coastal polyclad flatworm assemblages in the wider Caribbean. Marine Biology , 153: 769-778. Accessed May 22, 2011 at http://www.springerlink.com/content/t25n0553873323m4/ .

Ritson-Williams, R. 2003. Checklist of polyclad flatworms (Platyhelminthes) from Micronesian coral reefs. Micronesica , 2003/35-36: 189-199. Accessed May 22, 2011 at http://university.uog.edu/up/micronesica/abstracts_35-36/pdfs_3536/10-flatworms.pdf .

Seifarth, W. 2002. "Marine flatworms of the world - anatomy of polyclad flatworms" (On-line). Accessed May 22, 2011 at http://www.rzuser.uni-heidelberg.de/~bu6/flatintr.htm#bio_top .

Tan, R. 2008. "Persian carpet worm" (On-line). Wild Fact Sheet. Accessed May 22, 2011 at http://www.wildsingapore.com/wildfacts/worm/polycladida/bedfordi.htm .