A) It was unintentionally released into the Mediterranean by the Oceanographic Museum of Monaco.
B) Its invasive range extends at least as far as Spain on the west and Croatia on the east.
C) It is toxic to humans and other mammals.
D) It has evolved cold resistance.

A) can have large ecological effects in their new communities.
B) that become established are easy to control.
C) are often toxic.
D) always cause a decline in biological diversity of the communities they invade.

A) In theory, a community is defined only by abiotic factors of the area; in practice, communities are delineated by biological attributes as well.
B) In theory, communities consist of all species present; in practice, biologists usually study only a subset of the species.
C) In theory, communities can be defined by physical or biological characteristics, but in practice, these characteristics are difficult to measure and are not used.
D) There is no difference between the theoretical concept of a community and how it is defined in practice.