Symbiosis: “living together” (of unlike organisms)
Symbioses can be classified based on the effect felt by the partners. For instance,
- Parasitism: bad for the host; good for the symbiont
- Commensalism: neutral for the host; good for the symbiont
- Mutualism: good for both the host and the symbiont
Typically, the larger of the partners is called the host (e.g. the crinoids), while the smaller is referred to as the symbiont or associate. However, all organisms that live together are symbionts based on the definition above.
For crinoids and their associates, it is difficult to tell what effect the association has on the host. As a result, I will use the general terms of “symbiont” or “associate” and not distinguish between parasitism, commensalism, or mutualism in most cases.