Parasitology

The Study of Parasites Morphology Classification Biology and physiology Parasite/Host interactions –Relationships –Reactions

What is a parasite? Type of symbiosis One species living at the expense of another species Host – both habitat and food Always does damage to host

Types of Symbiosis - Mutualism

Giant Sequoia Seed Dispersal Mature cone producing plant ~ years old Average cone is mature after 34 years Cones only release seeds when dry

Fire

Types of Symbiosis – Mutualism Long-horned wood-boring beetle

Types of Symbiosis - Mutualism Douglas squirrel

Types of Symbiosis - Commensalism

Terms to Describe Parasites Location on Host –Ectoparasite

Terms to Describe Parasites Location on Host –Endoparasite

Terms to Describe Parasites Time Spent on Host –Temporary – visit for food (tick) –Stationary Periodic – part of life cycle is parasitic (mermithid nematodes) Permanent – all stages are parasitic (cestodes)

Terms to Describe Parasites Incidental –Occasionally appear in unusual hosts –Example: Sheep liver fluke in dogs or cats Erratic or Aberrant –Occasionally found in unusual locations in the host –Example: Ascaris found in liver instead of intestine

Terms to Describe Parasites Obligate – must live as parasite Facultative – sometimes lives as parasite –Example: Blowfly

Adaptations Holding On! –Hooks, suckers, claws…

Adaptations Letting Go! –Natural outlets Alimentary canal, lungs, reproductive tract… –Example: Cestoda –Blood stream Blood sucking parasites –Example: Mosquitoes transmit plasmodium –Digestion by predators or scavengers

Taxonomic Tree of Animals

Parasitic Groups Viruses (not covered) Bacteria (not covered) Plants (not covered) Protozoans –flagellates –amoebae –sporozoans –ciliates Helminths –Flukes –Tapeworms –Roundworms –Spiny-headed worms Leeches Arthropods –crustaceans –lice –mites –ticks –mosquitoes –flies –fleas Vertebrates (not covered)

Microhabitats of Parasites Ectoparasites –hair/feathers –skin –mouth –gills

Microhabitats of Parasites Endoparasites (either intracellular or extracellular) –Intestine and liver –Heart, blood vessels and lymph nodes –lungs and air passages –kidney –muscles and connective tissue –central nervous system and sensory structures –reproductive structures

Adaptations to Microenvironments Ectoparasites Falling or being pulled off –Structures to hold on Example: tarsi of lice

Adaptations to Microenvironments Intestine Peristalsis –Structures to attach to intestinal lining Example: scolex of tapeworm

Adaptations to Microenvironments Intestine Digestive enzymes and acids –Resistant tegument Example: complex carbohydrate layer in tapeworms

Adaptations to Microenvironments Intestine Low oxygen environment –Anaerobic respiration –Unique biochemical pathways –Produces less ATP