Researchers have identified two genes-follistatin and activin-as having an important role in the ability of certain flatworms to identify wounds that require the production of new tissue.

ONE MAY SUPPOSE that a rich polyclad fauna exists along the shores of the Hawaiian Islands, but our knowledge of Hawaiian polyclads is, in fact., very limited. As far as I can ascertain, only the follo.wing species are recorded from the Hawaiian Islands in the literature: Planocera hawaiiensis Heath, 1907; Taenioplana teredini Hyman, 1944; and 5tylochoplana inquilina Hyman, 1950. The first meri...

This review is an account of research into the biochemistry of lipids of platyhelminth parasites. Taking as high benchmark major metabolic pathways of vertebrates we summarize catabolic and synthesis routes now thought to be characteristic of this group. We emphasize the litlle recent information that exists on intermediary metabolism in these parasites. However, new data may be challenging old...

We describe "universal" DNA primers for polymerase chain reaction (PCR) amplification of a 710-bp fragment of the mitochondrial cytochrome c oxidase subunit I gene (COI) from 11 invertebrate phyla: Echinodermata, Mollusca, Annelida, Pogonophora, Arthropoda, Nemertinea, Echiura, Sipuncula, Platyhelminthes, Tardigrada, and Coelenterata, as well as the putative phylum Vestimentifera. Preliminary c...

Sex allocation theory for simultaneous hermaphrodites predicts an influence of the mating group size on sex allocation. Mating group size may depend on the size of the group in which an individual lives, or on the density, but studies to date have not distinguished between the two factors. We performed an experiment in which we raised a transparent simultaneous hermaphrodite, the flatworm Macro...

Available evidence strongly suggests that alternative, Earth-bound explanations should be sought first for the occurrence of a single bipolar planarian flatworm returning from space travel. Double-headed worms have been amply documented as arising under experimental conditions as well as spontaneously in stock cultures of planarians.

Previous studies on sex allocation in simultaneous hermaphrodites have typically focused either on evolutionary or one-time, ontogenetic optimization of sex allocation, ignoring variation within an individual's lifetime. Here, we study whether hermaphrodites also possess facultative sex allocation, that is, a phenotypic flexibility, allowing them to distribute resources to either sex in an oppo...

Pomacea canaliculata is a common gastropod in freshwater habitats from Central and Northern Argentina, extending northwards into the Amazon basin. Several Platyhelminthes have been reported associated to P. canaliculata, sharing an intimate relationship with this gastropod host. The objectives of this study were to describe the symbiotic species assemblages associated to P. canaliculata in the ...