Distribution

Trematodes are found around the world. The presence of their host species is often the limiting factor in their geographic distribution. For example, a flatworm that uses a mol-lusk as its host occurs only where that mollusk lives. Nonetheless, the distribution of a particular trematode can span large areas, particularly if their host species live in a broad range of habitats; or if members of the host species, like birds, are able to run or fly over vast regions.

In many cases, the species' distributions follow their hosts. For example, hosts of Uvulifer ambloplitis include snails, fishes, and birds. With such a complex life cycle, the trematodes distribution is a combination of the ranges of all three animals. As another example, the aspidogastrids infect mollusks, teleost fishes, and turtles, presenting another complex distribution pattern.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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