Can anybody give me a pdf or note about the flatworms?

Flatworms

James H. Thorp, D. Christopher Rogers, in Field Guide to Freshwater Invertebrates of North America, 2011

B Reproduction and Life History

Some flatworms, especially those living in temporary aquatic habitats, reproduce only once per year (univoltine), while other species are multivoltine, with the number of generations depending on environmental favorability. Most flatworms reproduce sexually, and almost all species are hermaphroditic. Although gamete exchange is most common, self-fertilization is possible in some species. Eggs are laid singly on a hard substrate, are grouped into clusters (sometimes stalked), or are placed in cocoons. Miniature flatworms emerge from eggs which have been attached to the substrate. These usually develop directly (without intermediate larval stages) into adults and differ only in size and presence of reproductive organs. A few species are ovoviviparous (young brooded inside parent) or have a distinct larval stage. Asexual reproduction occurs seasonally in many taxa and is the only form of reproduction in a few species. This form of reproduction involves differentiation of the adult body into distinct units (zooids) followed by separation into small flatworms via transverse division of the adult body. This process is aided by the remarkable regenerative abilities of flatworms.

Under demanding environmental conditions, flatworms produce resistant eggs able to survive desiccation of the surrounding environment or the animal may enter diapause (a very low metabolic state) and encyst as a whole animal or fragment of the adult.

Sexually reproducing flatworms can live from a few weeks to a few months (not counting periods of encystment), while the life span of asexual species is theoretically indefinite.

oceans

indian ocean

pacific ocean

atlantic ocean

arctic ocean

southern ocean

as the gila monster consumes the eggs or young of the desert cottontail and gambel's quail, thus its main food supply is only accessible for a restricted time duration every year. however, for this, the gila monsters exhibit three adaptations, which elevate their survival rate in the desert condition.  

first, is that they possess huge bodies, and can consume greater concentrations of food during a small period. secondly, they require to feed infrequently as they can accumulate fat in their tails. ultimately, their rate of metabolism is very low, so that they can burn their reservoirs of fat gradually.