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By way of example, a parasite that reproduces in an intermediate host may require, as part of their life cycle, that the intermediate host be eaten by a predator at a higher trophic level, and some parasites are capable of altering the behavior of the intermediate host to make such predation more likely; [1] [2] a mechanism that has been called ...
A parasite may evolve to become less harmful for its host or a host may evolve to cope with the unavoidable presence of a parasite—to the point that the parasite's absence causes the host harm. For example, although animals parasitised by worms are often clearly harmed, such infections may also reduce the prevalence and effects of autoimmune ...
The appearance and behaviour of the sporocysts is a case of aggressive mimicry, where the parasite vaguely resembles the food of the host, thereby gaining the parasite entry into the host's body by being eaten. This is unlike most other cases of aggressive mimicry, in which the mimic eats the duped animal. [13]
A perspective on the evolutionary options can be gained by considering four questions: the effect on the reproductive fitness of a parasite's hosts; the number of hosts they have per life stage; whether the host is prevented from reproducing; and whether the effect depends on intensity (number of parasites per host). From this analysis ...
Dividing T. gondii parasites. Toxoplasma gondii (/ ˈ t ɒ k s ə ˌ p l æ z m ə ˈ ɡ ɒ n d i. aɪ,-iː /) is a species of parasitic alveolate that causes toxoplasmosis. [3] Found worldwide, T. gondii is capable of infecting virtually all warm-blooded animals, [4]: 1 but felids are the only known definitive hosts in which the parasite may undergo sexual reproduction.
Parasites need a host body and the haematophagous insect triatomine (descriptions "assassin bug", "cone-nose bug", and "kissing bug") is the major vector in accord with a mechanism of infection. The triatomine likes the nests of vertebrate animals for shelter, where it bites and sucks blood for food.
The parasite then replaces the fish's tongue by attaching its own body to the muscles of the tongue stub. [7] The parasite apparently does not cause much other damage to the host fish, [2] but Lanzing and O'Connor (1975) reported that infested fish with two or more of the parasites are usually underweight. [8]
These larvae grow and take on a sac-like appearance. This stage is known as the sporocyst and it forms a central body in the snail's digestive gland that extends into a brood sac in the snail's head, muscular foot and eye-stalks. It is in the central body of the sporocyst where the parasite replicates itself, producing many tiny embryos .