''Pseudobiceros hancockanus'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of hermaphroditic marine

flatworm Platyhelminthes (from the Greek language, Greek πλατύ, ''platy'', meaning "flat" and ἕλμινς (root: ἑλμινθ-), ''helminth-'', meaning "worm") is a Phylum (biology), phylum of relatively simple bilaterian, Segmentation (biology), ...

in the family

Pseudocerotidae Pseudocerotidae is a family of flatworm Platyhelminthes (from the Greek language, Greek πλατύ, ''platy'', meaning "flat" and ἕλμινς (root: ἑλμινθ-), ''helminth-'', meaning "worm") is a Phylum (biology), phylum of relatively ...

. It is also known as Hancock's flatworm.

Description

According to the ''Baensch Marine Atlas,'' "''P. hancockanus'' is intense blue to black with white and orange peripheral bands and a purple fringe. The two short cephalic antennaie are easily overlooked because they are the same color as the body. Inferiorly, this species is purple with a medial line." ''P. hancockanus'' is very similar in appearance to '' P. uniarborensis'', although the margin of ''P. uniarborensis'' is translucent gray with a white line only on the outside, while the margin of ''P. hancockanus'' is pure bright white. It can grow up to 14 cm (5.5 inch) in length.

Habitat and distribution

''Pseudobiceros hancockanus'' lives in warm seas, sometimes on

coral Corals are colonial marine invertebrates within the subphylum Anthozoa of the phylum Cnidaria. They typically form compact Colony (biology), colonies of many identical individual polyp (zoology), polyps. Coral species include the important Coral ...

reefs, other times among coral fragments or stones. It has been observed near such places as

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...

Fiji Fiji, officially the Republic of Fiji, is an island country in Melanesia, part of Oceania in the South Pacific Ocean. It lies about north-northeast of New Zealand. Fiji consists of an archipelago of more than 330 islands—of which about ...

, and

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Diet

It is thought to feed on small invertebrates that live in sponges in coral reefs rather than eating the coral itself.

Behavior

''Pseudobiceros hancockanus'' can travel long distances, swimming by undulating the edges of its body.

Reproduction

Like other members of the genus ''

Pseudobiceros ''Pseudobiceros'' is a genus of flatworms. Like all flatworms, Pseudobiceros are hermaphrodites. This particular genus engages in penis fencing. When the "winner" touches its penis to the "skin" of the other, insemination occurs, and the "loser" ...

'', ''P. hancockanus'' is

hermaphroditic A hermaphrodite () is a sexually reproducing organism that produces both male and female gametes. Animal species in which individuals are either male or female are gonochoric, which is the opposite of hermaphroditic. The individuals of many ...

with each individual able to function as either a male or female. Mating between two such worms involves

penis fencing __NOTOC__ Penis fencing is a mating behavior engaged in by many species of flatworm, such as '' Pseudobiceros hancockanus''. Species which engage in the practice are hermaphroditic; each individual has both egg-producing ovaries and sperm-produci ...

, as each worm tries to inject sperm into the other with one of its two stubby penises, while trying to avoid being inseminated itself. One explanation advanced for this behavior is that the female role entails more investment in the resulting fertilized eggs. Another possible explanation is that the duel awards mating advantage to the better of two dueling partners—so that the penis duel's loser, becoming the "female," is compensated by creating offspring with genes even better than hers.

References

External links

PBS website with video of ''Pseudobiceros hancockanus'' penis-fencing
{{Taxonbar, from=Q3015084 Turbellaria Animals described in 1876