What is the Difference Between Host and Parasite

The main difference between host and parasite is that the host is the cell or the organism that harbours another organism or a biological entity whereas the parasite is the organism that lives at the expenses of the host. Furthermore, the host may or may not experience harm while parasite always gets the benefit.

Host and parasite are the two sides of a type of symbiotic relationship called parasitism.

Key Areas Covered

1. What is a Host
     – Definition, Types, Features
2. What is a Parasite
     – Definition, Types Features
3. What are the Similarities Between Host and Parasite
     – Outline of Common Features
4. What is the Difference Between Host and Parasite
     – Comparison of Key Differences

Key Terms

Commensalism, Host, Mutualism, Parasite, Parasitism, Symbiotic Relationship

What is a Host

The host is the organism that harbours another organism in a symbiotic relationship. There are three types of symbiotic relationships as mutualism, commensalism or parasitism. In mutualism, the host benefits. While, in commensalism, the host does not get benefits or losses/harm. But, in parasitism, the host gets harmed. For example, take termites. Termites are an example of a host in a mutualistic relationship with protozoa in which the protozoa live inside the gut of the termite, easing the digestion of the cellulose. Whales, turtles, and sharks are examples of hosts in a communalistic relationship with remoras. Here, the remoras can adhere to their host to be freely transported.

Figure 1: Nurse Shark with Remoras

In parasitism, we can identify several types of hosts. Moreover, the primary or the definitive host allows the maturation of the parasite and its sexual reproduction. However, the secondary or the intermediate host harbours only a short transition period of the parasite.

What is a Parasite

A parasite is an organism that depends at the expenses of the host. Parasites always show a lower organization than their host and there are major parasitic groups among arthropods, mollusks, annelids, nematodes, flatworms, and cnidarians. Furthermore, plants can also become parasitic on other plants. In addition, fungi, protozoa, bacteria, and viruses can become parasites as well. However, the main characteristic feature of a parasite is that it always benefits at the expenses of the host.

Figure 2: Bed Bug

There are several types of parasites:

1. Endoparasites – live inside the body of the host. Ex: Leishmania, Plasmodium, Entamoeba
2. Ectoparasites – live on the surface of the host. Ex: lice, mite, fleas, flies, bed bud
3. Permanent parasites – parasitic throughout the lifetime. Ex: head louse
4. Temporary parasites – visit their host for a short period of time. Ex: mosquito
5. Facultative parasites – become parasitic when the host becomes less fit. Ex: Entamoeba
6. Obligatory parasites – require a host in order to complete their life cycle. Ex: Plasmodium

Similarities Between Host and Parasite

• Host and parasite are the two components of parasitism.
• Both experience symbiotic relationships.
• Also, the host and the parasite, both live in the same biological niche.
• Moreover, they do not belong to the same species.

Difference Between Host and Parasite

Definition

A host refers to an organism that harbours a parasitic, a mutualistic, or a commensalist guest, the guest typically being provided with nourishment and shelter while a parasite refers to an organism that obtains nourishment and shelter on another organism. Thus, this is the basic difference between host and parasite.

Benefits

Alsio, a host may either get benefitted, harmed, or neither. However, the parasite always benefits.

Size

Size is a major difference between host and parasite. The host is always large than the parasite.

Organization

The host always has a higher organization while the parasite is always less organized than the host. Hence, this is another difference between host and parasite.

Conclusion

The host harbours another organism in either a mutualistic, communalistic or parasitic relationship. In parasitism, the host gets harmed by the parasite. On the other hand, a parasite is an organism that lives in or on a  host and benefits by deriving nutrients at the other’s expense. Therefore, the main difference between host and parasite is their role in the symbiotic relationship.

Reference:

1. Thompson, John N., and Timothy Fridtjof Flannery. “Community Ecology.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 8 Sept. 2017, Available Here
2. Chonkar, Shreya. “Classification of Parasites | Parasitology.” Biology Discussion, 5 Nov. 2016, Available Here

Image Courtesy:

1. “Nurse shark with remoras (cropped)” By Duncan Wright (User:Sabine’s Sunbird) – en: Image:Nurse shark with remoras.jpg (CC BY-SA 3.0) via Commons Wikimedia  
2. “Bed bug, Cimex lectularius” By Content Providers(s): CDC/ Harvard University, Dr. Gary Alpert; Dr. Harold Harlan; Richard Pollack. Photo Credit: Piotr Naskrecki –  (Public Domain) via Commons Wikimedia