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Color Change and the Ecology of the Marine Isopod Idothea (Pentidothea) Montereyensis Maloney, 1933
Author(s) -
Lee Welton L.
Publication year - 1966
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1935640
Subject(s) - ecology , algae , intertidal zone , population , habitat , red algae , biology , demography , sociology
The isopod Idothea montereyensis lives on marine plants in the rocky intertidal zone on the west coast of North America. It occurs in red, green and brownish color varieties which usually match the color of the plant on which the isopod is found, and individuals are capable of undergoing color change when transferred to plants of another color. A population of Idothea montereyensis occurs on the eelgrass Phyllospadix scouleri which forms large beds at about the 0.0 tidal level; these animals are subjected to wave action which may be severe during the winter. Another population occurs inshore of the Phyllospadix on various species of red algae which grow in the more protected deeper pools and channels. During the year, when large numbers of young are released, there is a massive exchange of individuals between the Phyllospadix and the red algal populations. Young which cannot hold on in the exposed Phyllospadix beds are swept in to the inshore red algae, while, presumably as a result of population pressure, the adult animals on inshore red algae move out to the Phyllospadix beds. The result of these major population exchanges is clearly advantageous. Young which cannot hold on to the Phyllospadix are provided with a protected habitat for development and growth on the inshore red algae, whereas the adults moving to the Phyllospadix are provided with ample space and food in a region where they are not competing strongly with their own young for these things. It is the middle—sized and larger animals which survive through the winter on Phyllospadix; the summer young grow and develop in the protected inshore areas. The ability to change color may allow the animals to utilized for food and substrate a larger quantity and variety of intertidal plants, with greater safety from predators, than would be possible without color change. It may provide camouflage to animals within a relatively short time after the occurrence of highly advantageous shifts in habitat.