Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water by passing the water over a specialized filtering structure. Some animals that use this method of feeding are clams, sponges, baleen whales, many fish; some birds, such as flamingos and certain species of duck, are filter feeders. Filter feeders can play an important role in clarifying water, are therefore considered ecosystem engineers, they are important in bioaccumulation and, as a result, as indicator organisms. Most forage fish are filter feeders. For example, the Atlantic menhaden, a type of herring, lives on plankton caught in midwater. Adult menhaden can filter up to four gallons of water a minute and play an important role in clarifying ocean water, they are a natural check to the deadly red tide. In addition to these bony fish, four types of cartilaginous fishes are filter feeders; the whale shark sucks in a mouthful of water, closes its mouth and expels the water through its gills.

During the slight delay between closing the mouth and opening the gill flaps, plankton is trapped against the dermal denticles which line its gill plates and pharynx. This fine sieve-like apparatus, a unique modification of the gill rakers, prevents the passage of anything but fluid out through the gills. Any material caught in the filter between the gill bars is swallowed. Whale sharks have been observed "coughing" and it is presumed that this is a method of clearing a build up of food particles in the gill rakers; the megamouth shark has luminous organs called photophores around its mouth. It is believed they may exist to lure small fish into its mouth; the basking shark is a passive filter feeder, filtering zooplankton, small fish, invertebrates from up to 2,000 tons of water per hour. Unlike the megamouth and whale sharks, the basking shark does not appear to seek its quarry. Unlike the other large filter feeders, it relies only on the water, pushed through the gills by swimming. Manta rays can time their arrival at the spawning of large shoals of fish and feed on the free-floating eggs and sperm.

This stratagem is employed by whale sharks. Mysidacea are small crustaceans that live close to shore and hover above the sea floor collecting particles with their filter basket, they are an important food source for herring, cod and striped bass. Mysids have a high resistance to toxins in polluted areas, may contribute to high toxin levels in their predators. Antarctic krill manages to directly utilize the minute phytoplankton cells, which no other higher animal of krill size can do; this is accomplished through filter feeding, using the krill's developed front legs, providing for a efficient filtering apparatus: the six thoracopods form a effective "feeding basket" used to collect phytoplankton from the open water. In the animation at the top of this page, the krill is hovering at a 55° angle on the spot. In lower food concentrations, the feeding basket is pushed through the water for over half a meter in an opened position, the algae are combed to the mouth opening with special setae on the inner side of the thoracopods.

Porcelain crabs have feeding appendages covered with setae to filter food particles from the flowing water. Most species of barnacles are filter feeders, using their modified legs to sift plankton from the water; the baleen whales, one of two suborders of the Cetacea, are characterized by having baleen plates for filtering food from water, rather than teeth. This distinguishes them from the other suborder of the toothed whales; the suborder contains fourteen species. Baleen whales seek out a concentration of zooplankton, swim through it, either open-mouthed or gulping, filter the prey from the water using their baleens. A baleen is a row of a large number of keratin plates attached to the upper jaw with a composition similar to those in human hair or fingernails; these plates are triangular in section with the largest, inward-facing side bearing fine hairs forming a filtering mat. Right whales are slow swimmers with large mouths, their baleen plates are narrow and long — up to 4 m in bowheads — and accommodated inside the enlarged lower lip which fits onto the bowed upper jaw.

As the right whale swims, a front gap between the two rows of baleen plates lets the water in together with the prey, while the baleens filter out the water. Rorquals such as the blue whale, in contrast, have smaller heads, are fast swimmers with short and broad baleen plates. To catch prey, they open their lower jaw — 90° — swim through a swarm gulping, while lowering their tongue so that the head's ventral grooves expand and vastly increase the amount of water taken in. Baleen whales eat krill in polar or subpolar waters during summers, but can take schooling fish in the Northern Hemisphere. All baleen whales except the gray whale feed near the water surface diving deeper than 100 m or for extended periods. Gray whales live in shallow waters feeding on bottom-living organisms such as amphipods. Bivalves are aquatic molluscs. Both shells are symmetrical along the hinge line; the class has 30,000 species, including scallops, clams and mussels. Most bivalves are filter feeders, extracting organic matte

An unpublished manuscript entitled Ordenanzas del Baratillo de México was signed and dated in 1754 by Pedro Anselmo Chreslos Jache a pseudonym for an educated Spaniard. It is a satirical piece of eighteenth-century colonial literature written in New Spain, which sought to offer an alternative view of life in colonial Spanish America; the Baratillo was an infamous market in Mexico City known for the sale of used items, many of, stolen and were cheaply priced. It was a place for the poor and lower class of Mexico racially mixed people, to mingle and purchase items for subsistence. Ordenanzas, or official decrees, were established to regulate New Spanish society in general; the author’s 377 ordenanzas mimicked the official statutes, but would reverse the power system based on the sistema de castas. In effect, Chreslos Jache mocks the limpieza de sangre by creating a separate system of classification for Spaniards. For example, “medio Españoles” and “cuartilla de Español” were parodies of terms to identify persons of mixed race, like “mestizo”, “castiza”, “lobo”, countless others.

The purpose of this manuscript was to show a chaotic view of life in Mexico in which the castas used a variety of strategies to substantiate their control over society and that the casta system itself is self-regulating. Chreslos Jache pokes fun at this idea of self-regulation by making up ridiculous names that are impossible to adequately translate for the terminology of the sistema de castas; the manuscript states that the sistema de castas was mocked by the formation of the Baratillo “brotherhood”, composed of non-whites mulattos. This brotherhood banned membership to Spaniards and their descendants, instead made them targets of the brotherhood’s scams. By using the Baratillo brotherhood, Chreslos Jache inverts the traditional racial attitude of the time where Spaniards and creoles dominated the system; the manuscript reinforced race as a category of power differentiation within New Spain because it was a text that circulated among the educated elite in a time when upper class people were literate.

The significance of this satirical manuscript in relation to Casta paintings is that, much like the manuscript, the paintings reflect racial debate and contribute to the interpretation of racial culture during the second half of the eighteenth-century in New Spain

Charles Joseph Nourse was an American football player and lawyer. He played college football at Harvard University and was a consensus first-team selection to the 1908 College Football All-America Team. Nourse was born in 1888, he attended preparatory school at St. Paul's School in New Hampshire; as an undergraduate, Nourse studied law at Harvard College from 1905 to 1909. He weighed 197 pounds while at Harvard, he played on the freshman football team in 1906 and on the Harvard Crimson football team in 1907 and 1908. After the 1908 season, he was selected as a consensus first-team center on the 1908 College Football All-America Team. After receiving his bachelor's degree from Harvard in 1909, Nourse spent three years at Columbia Law School, he was editor of the Law Review at Columbia and graduated in 1912. He practiced with the law with the firm of Winthrop & Stimson in New York City, with the firm of Prince & Burlingame. During World War I, Nourse served in the 31st Field Artillery, attaining the rank of captain, serving under Henry L. Stimson, who became the U.

S. Secretary of State and Secretary of War. After the war, Nourse returned to the practice of law. From 1927 to 1970, he was with the Wall Street law firm of Winthrop, Putnam & Roberts and its predecessor firm, Nourse & Pettit, his clients included the New York Trust Company. Nourse was married in June 1922 to Margaret Lawrence Strong in a ceremony at Short Hills, New Jersey. In his years, Nourse lived on East 67th Street in Manhattan and at Oyster Bay, Long Island, he died in April 1974 at his home in Manhattan