2. DEFINITIONS OF TYPES O P SYMBIOSES
9
ships between organisms in the marine environment, or in any environment for that matter, are examined, the line of demarcation between
parasitism and predation sometimes becomes extremely difficult to
recognize. This is especially true if the often used criterion of “ inflicting
injury to host ” is employed in defining parasitism, since this would
indicate that both predation and parasitism are types of interactions
that result in negative effects on the survival of one of the populations.
Although this is true with certain parasites, it is by no means the rule
as it is with predators.
With the acceptance of the definition of parasitism given earlier,
the distinction between parasitism and predation becomes more
recognizable although the problem is by no means completely resolved.
For example, in cases where one member of the association feeds on the
tissues of the other and yet does not rapidly destroy the latter, should
this be considered as parasitism or predation? It would appear that the
solution to this dilemma lies in the qualifying phrase (I obligatory
metabolic dependence ” that is used to define parasitism. If the
aggressive member of the association is obligatorily and specifically
dependent upon the tissues of the passive member, such a relationship
may be categorized as parasitism. However, if the whole or parts of other
organisms, within a broad spectrum, may be substituted for the passive
member, the association may be considered as a predator-prey
relationship.
Since this review is only concerned with symbiotic associations,
predators of marine molluscs are not considered although a few invertebrates whose role as either parasite or predator remains uncertain
are mentioned briefly.
9
ships between organisms in the marine environment, or in any environment for that matter, are examined, the line of demarcation between
parasitism and predation sometimes becomes extremely difficult to
recognize. This is especially true if the often used criterion of “ inflicting
injury to host ” is employed in defining parasitism, since this would
indicate that both predation and parasitism are types of interactions
that result in negative effects on the survival of one of the populations.
Although this is true with certain parasites, it is by no means the rule
as it is with predators.
With the acceptance of the definition of parasitism given earlier,
the distinction between parasitism and predation becomes more
recognizable although the problem is by no means completely resolved.
For example, in cases where one member of the association feeds on the
tissues of the other and yet does not rapidly destroy the latter, should
this be considered as parasitism or predation? It would appear that the
solution to this dilemma lies in the qualifying phrase (I obligatory
metabolic dependence ” that is used to define parasitism. If the
aggressive member of the association is obligatorily and specifically
dependent upon the tissues of the passive member, such a relationship
may be categorized as parasitism. However, if the whole or parts of other
organisms, within a broad spectrum, may be substituted for the passive
member, the association may be considered as a predator-prey
relationship.
Since this review is only concerned with symbiotic associations,
predators of marine molluscs are not considered although a few invertebrates whose role as either parasite or predator remains uncertain
are mentioned briefly.