Benefited is parasite Harmed is host PARASITISM It is a type of antagonistic relationship between organisms of different species where one is benefited and another is harmed Benefited is parasite Harmed is host

TYPES OF PARASITES Parasitism can take place in plants as well as in animals In case of plants they described as PHYTOPHAGOUS In case of animals they described as ZOOPHAGOUS

Types of parasites They are further of two types on the basis of position in relation to their host ENDOPARASITES: which lives inside the body of host and damage the cells,tissues,body fluids or gut by taking their contents They can be cytozoic,histozoic,gut or body fluid parasites. (e.g. Plasmodium,Trichinella,Taenia,Schistosoma.) ECTOPARASITES: which remain outside of Host body & feed on the dead or live tissues of skin or suck blood. (e.g.Bird lice,scale mite,head louse.)

Host-Parasite period of relationship They are of two types PERMANENT: mostly parasitic for the whole of their life,send their progeny as cysts ( parasitic protozoans ) or as Capsules. e.g. Ascaris, Fasciola Taenia. TEMPORARY: parasitic for the some part of their life,rest of life as free living organism. (e.g. Ancylostoma, Leaches, lice, bed bug.)

ADAPTATIONS The changes occur in morphological and physiological characters of any organism due to some climatic or surrounding conditions are called ADAPTATIONS

There are two types of adaptation MORPHOLOGICAL ADAPTATIONS: changes occur in morphological / external characters PHYSIOLOGICAL ADAPTATIONS: changes occur in physiological / Internal characters

PARASITIC ADAPTATIONS IN HELMINTHES Phylum Platyhelminthes & Aschelminthes are included in Helminthes group. eg.Platyhelminthes-Taenia,Fasciola,Schistosoma,Echinococcus. eg.Aschelminthes- Ascaris,Wuchereria,Ancylostoma.

Ascaris lumbricoids

Schistosoma mansoni

MORPHOLOGICAL ADAPTATIONS Thick Cuticle: It helps in investing the roundworms protect them from digestive enzymes and antitoxins of host. Muscular Pharynx: It enables the parasites to suck fluid from the surroundings. Simple Sense Organs: These are correlated to the life of the parasites in sheltered habitat. Minute Resistant Eggs: Covering of eggs protect them and the juveniles develop in them from untoward environmental factors .

The Tegument of a Parasitic Cestode The Outer Surface of a Parasitic Monogenean The tegument found in the monogeneans is characterised by the presence of numerous microvilli on the surface. The Tegument of a Parasitic Cestode

Formation of new structures- Adhesive organs:To have a firm grip with the host tissues , parasitic helminthes especially flukes & tapeworms developed adhesive organs like suckers& hooks. Gryodactylus (a monogenetic fluke) has developed claws ,Diphllobothrium (broad tapeworm) developed longitudinal grooves called botheria. The nematodes have well developed epidermal musculature to compensate the absence of adhesive organs.

Each Fluke produces 500,000 capsules Excessive multiplication:prolific breeders to compensate loss during transfer from one host to another through unfavourable conditions for the continuation of their species Each Fluke produces 500,000 capsules A Tapeworm apolyses 2500 gravid proglottids every year for about 30 years .Each gravid proglottid contains 30,000 to 40,000 onchospheres. Single female Ascaris has 27 million capsules in its uteri and lays the capsules @15000 -200,000 capsules per day. Ankylostoma produces 10,000-20,000 eggs per day. Trichinella spiralis produces 1500-2500 juveniles in her body cavity.

Degeneration ( complete or partial) of organs which has lost their importance – (a) locomotory organs;as these live in the habitats with abundance of food.,only the free living larval stages of Fasciola retain epidermal cilia and vibratile tail. (b)Digestive system;due to abundance of food & little competition (c) Neurosensory organs;being in well protected habitat with uniform conditions,nervous & sense organs is of low organisation if present.

PHYSIOLOGICAL ADAPTATIONS Anaerobic Respiration: It enables the parasitic roundworms to survive in oxygen-deficient media such as intestinal contents. Secretion of Ant enzymes: The intestinal roundworms secrete ant enzymes to protect themselves from the digestive enzymes of host. Osmotic Adaptations: It enables the parasite to successfully live in different media. Chemo taxis: parasites must be having marked chemo taxis that guide them in finding their final habitat in host. Excessive Egg Production: It compensates lack of asexual multiplication and wastage that occurs during transfer from one host to another. Power of Locomotion: It enables to maintain their position in their habitat. Nutritional adaptation:nicely adapted to absorb & distribute nutrirnts by spreading strobila or forming suctorial apparatus.

Life cycle of Ancylostoma duodenale

Life cycle of Wuchereria bancrofti

Parasites have moulded themselves well for their survival