Biology 1st Edition by Jerome Krueger, Kendra Hill, Robert Noyd

تمرين 2

Barnacles are marine crustaceans related to the more familiar crabs and lobsters. As barnacles mature, they excrete a gluelike substance that permanently attaches them to surfaces including rocks and animals ( Fig. ). Most barnacles are suspension feeders and reach into the surrounding water with modified legs. These feathery legs beat rhythmically to draw plankton and detritus into their hard shell for consumption. Whales often have large collections of barnacles attached to their bodies that remain for the rest of the whales' lives. Based on this information, what is the relationship between whales and barnacles? Certain species of barnacles extend their feeding legs directly into their host and derive their nutrition that way. What type of relationship does this represent?
Figure Barnacles attached to a whale.