Many monogeneans are strictly host-specific; that is, they are limited to a single or a few closely related hosts. Skin parasites may be widespread on the surface of the host's skin or concentrated in specific areas. Many monopisthocotyleans use two pairs of counter-rotating hamuli, one pair on their ventral surface and one pair on the dorsal surface, to attach themselves between two adjacent secondary gill lamellae on one of the fish's primary lamellae. The monocotylid monopistho-cotyleans are parasites of elasmobranch fishes, and must occupy internal sites such as their nasal fossae (cavities), body cavity, and cloaca. Another monopisthocotylean, Amphibdella, spends its early life inside the heart of an electric ray, moving to the gills when it is an adult and releasing its eggs into the ray's gill cavity. Many polyopisthocotyleans use their clamps to grip one or two secondary gill lamellae. Other poly-opisthocotyleans (polystomatids) use suckers to attach themselves inside the bladders of frogs and toads, or the bladders or mouths of freshwater turtles. Oculotrema hippopotami is the only monogenean that infests a mammal; it is a polystomatid that lives beneath the eyelids of the hippopotamus. The gy-rodactylid Isancistrum lives on the skin of squids and is the only monogenean parasite that infests an invertebrate.

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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