4 Turbellarians are monoecious with the reproductive systems adapted for internal fertilization. And the monogenetic flukes (class Monogenea) are mostly ectoparasites of fishes.
Trochus pyramis Born is of gonophores.The male reproductive system is mainly composed of the spermaries and spermaductus, instead of mating and others glands.
In a population in which all males and females divorce their partners, the best strategy for an individual bird is also divorce, because every bird has a high chance of remating.
Take the experimental rats into 8 groups including 3 groups for therapeutic dose,3 groups for toxic dose and 2 groups for lethiferous dose, with 10 rats for each group and male and female for half.