Title: The American Museum journal
Identifier: americanmuseumjo16amer (find matches)
Year: c1900-(1918) (c190s)
Authors: American Museum of Natural History
Subjects: Natural history
Publisher: New York : American Museum of Natural History
Contributing Library: American Museum of Natural History Library
Digitizing Sponsor: Biodiversity Heritage Library

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362 THE AMERICAN MUSEUM JOURNAL breathing function of the gills is merely secondary. The gills have developed great brushes of cilia and have been modified to serve primarily in the collec- tion of food. Rapid movement of the cilia causes a continual flow of water, from which the cilia sift out enormous numbers of diatoms, Protozoa, and mi- nute floating particles of dead organic matter, which are conveyed to the mouth through a special food groove located on the lower edge of the gills. The process goes on day and night and the food supply is practically inex- haustible. Even though the members of a community in a favorable situation are packed together as closely as sar- dines in a box, there is usuallv food
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Photomicrograp)! of the main hyssus f,'l<ni'l. showing the glandular memhranes that hang down in the byssiis cavity Hke a series of curtains. The sticky secretion is forced out througii the aperture at the base where, on coming in contact with the sea water, it hardens into a tough rod enough for all as long as the avenue to the inhalant canal remains unobstructed. In very crowded portions of a community it is often necessary for the members to stand on their heads in order that the individual food streams be not impeded. The food supply of the mussel com- munity is a subject of great interest because it represents the ultimate food basis of all marine animals. Decaying eelgrass forms minute particles called "detritus," that contain nutritive com- pounds related to starch, which the mus- sel utilizes to some extent, but the most important source of its food is the group of plants constituting the diatoms. They represent the energy of sunshine combined with air, water, and salts in a form available for food. In their com- position the three food principles, pro- tein, carbohydrate, and fat are present and they are built up at a rate that is astonishing and beyond our powers of comprehension. Submerged in a me- dium where they are supplied with un- limited quantities of water, oxygen, and mineral salts, and with sunshine, the dia- toms are able to multiply and grow at a rate that puts the proverbial mustard seed to shame. As the late Professor Brooks has rigorously demonstrated, one of these microscopic organisms under fa- vorable conditions is capable of filling the ocean solid in less than a week, if all its progeny were to live and keep on multi- plying at the maximum rate during that period. This is a stupendous fact and it must be comprehended before one can understand life in the sea. It explains why such enormous communities of shell- fish can be supported on a limited area of the sea's floor. Unlimited food supply is coupled with almost unlimited powers of repro- duction. In the sea mussel we find the strange condition in which practically the whole body becomes a storehouse

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