A Balancing Act; Exploring Multiple Hosts Parasites and Parasitoids

Let's discuss parasites a little bit, and talk about how they take advantage of so many lives instead of just one. C'mon, let's not crucify parasites like they are the demons in our world, they actually have some good just have they have their bad. Before we continue with the good and the bad of parasites, let's quickly define them.

To define parasite, let's take a look at people we refer to as party crashers who are not willing to put any work into getting the party started or running, but are just interested in leeching on every opportunity that shows up in the party and is willing to have every meal to themselves. Now that you understand that, take the party as another organism, and the party crashers as parasites. they can exist in different forms of life, from cells to tissues, and so on. The job of these hosts is to provide food, shelter, and ground to breed (like you have to provide a place for them to have fun and procreate). While some parasites would stay in a host, living their entire life depending on the host, so many parasites will not stay in one host. They will pass through a number of hosts just to reproduce, and some would even go on numerous vacations in the body of so many organisms. For instance;

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Euhaplorchis Californiensis is one parasite that lives in 3 hosts just to be able to reproduce. It is a parasitic trematode which we commonly know as a fluke. Its life cycle is very complex, involving multiple hosts from snails to killifish

The life circle of Euhaplorchis Californiensis starts with the horn snails ingesting eggs of the Euhaplorchis Californiensis. The eggs hatch inside the horn snail after which its larvae leave the snail and swim in the water until it is eaten by California killifish (Fundulus parvipinnis). The fish ingest them, but then the larvae trematode manipulate the behavior of the California killifish by messing with the brain of the fish, causing it to be eaten by birds like Great Blue Heron after which it reaches the adult stage. For me, that is a very stressful process, but these parasites tend to like them so much and do not care.

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Another parasite that has multiple hosts in its reproduction cycle is Leucochloridium paradoxum. When you see a snail with green-banded brood sac having that green sac as the name sounds, do not think it is natural. It is a result of Leucochloridium paradoxum present in the snail. The parasite lays its eggs in bird droppings initially which is then consumed by snails where the eggs hatch and the larvae penetrate the snail's tentacle tissues giving that green banded brood sac. The altered color of the snail's tissue allows it to be attractive to birds who then ingest the snails. In the bird's digestive system, the parasite completes its life cycle. It releases eggs in the digestive system of the bird which is then released in the droppings of the bird.

From the way it looks, the parasites are always getting it right as they have their host readily available to consume them, and this usually plays out well with smaller hosts as they are more in numbers and they do not often have choices with what they consume compared to large hosts but then there can be situations of Trophic vacuum where a particular ecological niche or level in a food chain is absent as a result of organisms not being present or being scarce but that doesn't mean that all of them would not make it through their hosts.

While some parasites allow their hosts to live, some of them do not. They like to have it all and so, they eat their hosts to survive. These parasites are parasitoids that first infect their host and then kill them in other to survive. A Braconid Wasp larva is an example of a parasitoid. The Braconid wasps lay eggs inside or on the caterpillar. As the eggs hatch, they feed on the caterpillar's internal organs until they are matured then burst through their hosts. They mature and then start to lay eggs on another caterpillar. Other parasitoids are the Tachinid fly, Hymenopteran Parasitic Wasps, and Strepsipterans.

For each of these parasites, their hosts serve as their own habitat, and adaptation is important for them. living through numbers of ecosystem isn't a new thing when it comes to so many organisms such as the frog but the difference is that it is free living, changing from one habitat to another but parasites would feed on their hosts, and as expected, live on their hosts. So we could say that they are just doing their own part to a healthy, balanced ecosystem or what do you think?