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 also a natural check to the deadly red tide.[1]
In addition to these bony fish, four types of cartilaginous fishes are also 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, which is a unique modification of the gill rakers, prevents the passage of anything but fluid out through the gills (anything above 2 to 3mm in diameter is trapped). 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.[2][3][4] The megamouth shark has luminous organs called photophores around its mouth. It is believed they may exist to lure plankton or small fish into its mouth.[5] The basking shark is a passive filter feeder, filtering zooplankton, small fish, and invertebrates from up to 2,000 tons of water per hour.[6] Unlike the megamouth and whale sharks, the basking shark does not appear to actively seek its quarry; but it does possess large olfactory bulbs that may guide it in the right direction. Unlike the other large filter feeders, it relies only on the water that is pushed through the gills by swimming; the megamouth shark and whale shark can suck or pump water through their gills.[6]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 also employed by whale sharks.[7]
Like all arthropods, crustaceans are ecdysozoans, a clade without cilia. Cilia play an important role for many filter feeding animals, but because crustaceans don't have them, they need to use modified extremities for filter feeding instead.[8]Mysidaceans live close to shore and hover above the sea floor, constantly collecting particles with their filter basket. They are an important food source for herring, cod, flounder, and striped bass. Mysids have a high resistance to toxins in polluted areas, and may contribute to high toxin levels in their predators.[citation needed]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 very efficient filtering apparatus:[9] the six thoracopods form a very 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, and then 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.[10] Most species of barnacles are filter feeders, using their highly modified legs to sift plankton from the water.[11]
Also some insects with aquatic larvae or nymphs are filter feeders during their aquatic stage. Such as some species of mayfly nymphs,[12]mosquito larvae,[13] and black fly larvae.[14] Instead of using modified limbs or mouthparts, some caddisfly larvae produce nets of silk used for filter feeding.[15]
Baleen whales
Mouth plates of a baleen whale
The baleen whales (Mysticeti), one of two suborders of the Cetacea (whales, dolphins, and porpoises), are characterized by having baleen plates for filtering food from water, rather than teeth. This distinguishes them from the other suborder of cetaceans, the toothed whales (Odontoceti). The suborder contains four families and fourteen species. Baleen whales typically seek out a concentration of zooplankton, swim through it, either open-mouthed or gulping, and 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.[16]Right whales are slow swimmers with large heads and mouths. Their baleen plates are narrow and very long— up to 4m (13ft) 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.[16]Rorquals such as the blue whale, in contrast, have smaller heads, are fast swimmers with short and broad baleen plates. To catch prey, they widely open their lower jaw— almost 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.[16] Baleen whales typically eat krill in polar or subpolar waters during summers, but can also take schooling fish, especially in the Northern Hemisphere. All baleen whales except the gray whale feed near the water surface, rarely diving deeper than 100m (330ft) or for extended periods. Gray whales live in shallow waters feeding primarily on bottom-living organisms such as amphipods.[16]
Bivalves are aquatic molluscs which have two-part shells. Typically both shells (or valves) are symmetrical along the hinge line. The class has 30,000 species, including scallops, clams, oysters and mussels. Most bivalves are filter feeders (although some have taken up scavenging and predation), extracting organic matter from the sea in which they live. Nephridia, the shellfish version of kidneys, remove the waste material. Buried bivalves feed by extending a siphon to the surface. For example, oysters draw water in over their gills through the beating of cilia. Suspended food (phytoplankton, zooplankton, algae and other water-borne nutrients and particles) are trapped in the mucus of a gill, and from there are transported to the mouth, where they are eaten, digested and expelled as feces or pseudofeces. Each oyster filters up to five litres of water per hour. Scientists believe that the Chesapeake Bay's once-flourishing oyster population historically filtered the estuary's entire water volume of excess nutrients every three or four days. Today that process would take almost a year,[17] and sediment, nutrients, and algae can cause problems in local waters. Oysters filter these pollutants,[18] and either eat them or shape them into small packets that are deposited on the bottom where they are harmless.
Bivalve shellfish recycle nutrients that enter waterways from human and agricultural sources. Nutrient bioextraction is "an environmental management strategy by which nutrients are removed from an aquatic ecosystem through the harvest of enhanced biological production, including the aquaculture of suspension-feeding shellfish or algae".[19] Nutrient removal by shellfish, which are then harvested from the system, has the potential to help address environmental issues including excess inputs of nutrients (eutrophication), low dissolved oxygen, reduced light availability and impacts on eelgrass, harmful algal blooms, and increases in incidence of paralytic shellfish poisoning (PSP). For example, the average harvested mussel contains: 0.8–1.2% nitrogen and 0.06–0.08% phosphorus[20] Removal of enhanced biomass can not only combat eutrophication and also support the local economy by providing product for animal feed or compost. In Sweden, environmental agencies utilize mussel farming as a management tool in improving water quality conditions, where mussel bioextraction efforts have been evaluated and shown to be a highly effective source of fertilizer and animal feed[21] In the U.S., researchers are investigating potential to model the use of shellfish and seaweed for nutrient mitigation in certain areas of Long Island Sound.[22]
Bivalves are also largely used as bioindicators to monitor the health of an aquatic environment, either fresh- or seawater. Their population status or structure, physiology, behaviour,[23] or their content of certain elements or compounds can reveal the contamination status of any aquatic ecosystem. They are useful as they are sessile, which means they are closely representative of the environment where they are sampled or placed (caging), and they breathe water all the time, exposing their gills and internal tissues: bioaccumulation. One of the most famous projects in that field is the Mussel Watch Programme in America.
Sponges have no true circulatory system; instead, they create a water current which is used for circulation. Dissolved gases are brought to cells and enter the cells via simple diffusion. Metabolic wastes are also transferred to the water through diffusion. Sponges pump remarkable amounts of water. Leuconia, for example, is a small leuconoid sponge about 10cm tall and 1cm in diameter. It is estimated that water enters through more than 80,000 incurrent canals at a speed of 6cm per minute. However, because Leuconia has more than 2 million flagellated chambers whose combined diameter is much greater than that of the canals, water flow through chambers slows to 3.6cm per hour.[24] Such a flow rate allows easy food capture by the collar cells. Water is expelled through a single osculum at a velocity of about 8.5cm/second: a jet force capable of carrying waste products some distance away from the sponge.
Tunicates take water in through a siphon and then expel filtered water through another siphon.
Tunicates, such as ascidians, salps and sea squirts, are chordates which form a sister group to the vertebrates. Nearly all tunicates are suspension feeders, capturing planktonic particles by filtering sea water through their bodies. Water is drawn into the body through the inhalant buccal siphon by the action of cilia lining the gill slits. The filtered water is then expelled through a separate exhalant siphon. To obtain enough food, a typical tunicate needs to process about one body-volume of water per second.[25]
Flamingos filter-feed on brine shrimp. Their oddly shaped beaks are specially adapted to separate mud and silt from the food they eat, and are uniquely used upside-down. The filtering of food items is assisted by hairy structures called lamellae which line the mandibles, and the large rough-surfaced tongue.[26]
Prions are specialised petrels with filter-feeding habits. Their name comes from their saw-like jaw edges, used to scope out small planktionic animals.[27]
The extinct swanAnnakacygna is speculated to be a filter-feeder due to its bill proportions being similar to those of shoveler ducks. It is unique in being a large, flightless marine animal, unlike the smaller still volant flamingos and prions.
Pterosaurs
Traditionally, Ctenochasmatoidea as a group has been listed as filter-feeders, due to their long, multiple slender teeth, clearly well adapted to trap prey. However, only Pterodaustro showcases a proper pumping mechanism, having up-turned jaws and powerful jaw and tongue musculature. Other ctenochasmatoids lack these, and are now instead thought to have been spoonbill-like catchers, using their specialised teeth simply to offer a larger surface area. Tellingly, these teeth, while small and numerous, are comparatively unspecialised to the baleen-like teeth of Pterodaustro.[28]
Boreopterids are thought to have relied on a kind of rudimentary filter feeding, using their long, slender teeth to trap small fish, though probably lacking the pumping mechanism of Pterodaustro. In essence, their foraging mechanism was similar to that of modern young Platanista "dolphins".[28][29]
Marine reptiles
Filter feeding habits are conspicuously rare among Mesozoicmarine reptiles, the main filter feeding niche being seemingly instead occupied by pachycormid fish. However, some sauropsids have been suggested to have engaged in filter feeding. Henodus was a placodont with unique baleen-like denticles and features of the hyoid and jaw musculature comparable to those of flamingos. Combined with its lacustrine environment, it might have occupied a similar ecological niche.[30][31] In particular, it was probably a herbivore, filtering out algae and other small-sized flora from the substrates.[32]Stomatosuchidae is a family of freshwater crocodylomorphs with rorqual-like jaws and minuscule teeth, and the unrelated CenozoicMourasuchus shares similar adaptations. Hupehsuchia is a lineage of bizarre Triassic reptiles adapted for suspension feeding.[33] Some plesiosaurs might have had filter-feeding habits.[34]
↑ Stadmark and Conley. 2011. Mussel farming as a nutrient reduction measure in the Baltic Sea: consideration of nutrient biogeochemical cycles. Marine Pollution Bull. 62(7):1385-8
↑ Lindahl O, Hernroth R., Kollberg S., Loo L.-O, Olrog L., Rehnstam-Holm A.-S., Svensson J., Svensson S., Syversen U. (2005). "Improving marine water quality by mussel farming: A profitable solution for Swedish society". Ambio. 34 (2): 131–138. Bibcode:2005Ambio..34..131L. doi:10.1579/0044-7447-34.2.131. PMID15865310. S2CID25371433.{{cite journal}}: CS1 maint: multiple names: authors list (link)
↑ Gotch, A. F. (1995) [1979]. "Albatrosses, Fulmars, Shearwaters, and Petrels". Latin Names Explained A Guide to the Scientific Classifications of Reptiles, Birds & Mammals. New York, NY: Facts on File. pp. 191–192. ISBN 0-8160-3377-3.
1 2 Wilton, Mark P. (2013). Pterosaurs: Natural History, Evolution, Anatomy. Princeton University Press. ISBN978-0691150611.
↑ Pilleri G., Marcuzzi G., Pilleri O. (1982). "Speciation in the Platanistoidea, systematic, zoogeographical and ecological observations on recent species". Investigations on Cetacea. 14: 15–46.{{cite journal}}: CS1 maint: multiple names: authors list (link)
↑ Rieppel, O. (2002). Feeding mechanisms in Triassic stem-group sauropterygians: the anatomy of a successful invasion of Mesozoic seas Zoological Journal of the Linnean Society, 135, 33–63
Clupeidae is a family of clupeiform ray-finned fishes, comprising, for instance, the herrings and sprats. Many members of the family have a body protected with shiny cycloid scales, a single dorsal fin, and a fusiform body for quick, evasive swimming and pursuit of prey composed of small planktonic animals. Due to their small size and position in the lower trophic level of many marine food webs, the levels of methylmercury they bioaccumulate are very low, reducing the risk of mercury poisoning when consumed.
Oyster is the common name for a number of different families of salt-water bivalve molluscs that live in marine or brackish habitats. In some species, the valves are highly calcified, and many are somewhat irregular in shape. Many, but not all oysters, are in the superfamily Ostreoidea.
Mussel is the common name used for members of several families of bivalve molluscs, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, which are often more or less rounded or oval.
Bivalvia or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of aquatic molluscs that have laterally compressed soft bodies enclosed by a calcified exoskeleton consisting of a hinged pair of half-shells known as valves. As a group, bivalves have no head and lack some typical molluscan organs such as the radula and the odontophore. Their gills have evolved into ctenidia, specialised organs for feeding and breathing.
Baleen whales, also known as whalebone whales, are marine mammals of the parvorder Mysticeti in the infraorder Cetacea, which use keratinaceous baleen plates in their mouths to sieve planktonic creatures from the water. Mysticeti comprises the families Balaenidae, Balaenopteridae (rorquals), Eschrichtiidae and Cetotheriidae. There are currently 16 species of baleen whales. While cetaceans were historically thought to have descended from mesonychians, molecular evidence instead supports them as a clade of even-toed ungulates (Artiodactyla). Baleen whales split from toothed whales (Odontoceti) around 34 million years ago.
Baleen is a filter-feeding system inside the mouths of baleen whales. To use baleen, the whale first opens its mouth underwater to take in water. The whale then pushes the water out, and animals such as krill are filtered by the baleen and remain as a food source for the whale. Baleen is similar to bristles and consists of keratin, the same substance found in human fingernails, skin and hair. Baleen is a skin derivative. Some whales, such as the bowhead whale, have longer baleen than others. Other whales, such as the gray whale, only use one side of their baleen. These baleen bristles are arranged in plates across the upper jaw of whales.
The megamouth shark is a species of deepwater shark. Rarely seen by humans, it measures around 5.2 m (17 ft) long and is the smallest of the three extant filter-feeding sharks alongside the relatively larger whale shark and basking shark. According to Sharkman's World Organization a total of 286 specimens have been observed or caught since its discovery in 1976. Like the other two planktivorous sharks, it swims with its mouth wide open, filtering water for plankton and jellyfish. It is recognizable from its large head with rubbery lips. The megamouth is so unlike any other type of shark that it is usually considered to be the sole extant species in the family Megachasmidae, though some scientists have suggested it may belong in the family Cetorhinidae.
The eastern oyster —also called the Atlantic oyster, American oyster, or East Coast oyster—is a species of true oyster native to eastern North and South America. Other names in local or culinary use include the Wellfleet oyster, Virginia oyster, Malpeque oyster, Blue Pointoyster, Chesapeake Bay oyster, and Apalachicola oyster. C. virginica ranges from northern New Brunswick south through parts of the West Indies to Venezuela. It is farmed in all of the Maritime provinces of Canada and all Eastern Seaboard and Gulf states of the United States, as well as Puget Sound, Washington, where it is known as the Totten Inlet Virginica. It was introduced to the Hawaiian Islands in the 19th century and is common in Pearl Harbor.
The basking shark is the second-largest living shark and fish, after the whale shark. It is one of three plankton-eating shark species, along with the whale shark and megamouth shark. Typically, basking sharks reach 7.9 m (26 ft) in length. It is usually greyish-brown, with mottled skin, with the inside of the mouth being white in colour. The caudal fin has a strong lateral keel and a crescent shape. Other common names include bone shark, elephant shark, sailfish, and sunfish. In Orkney, it is called hoe-mother, meaning "the mother of the piked dogfish".
Gill rakers in fish are bony or cartilaginous processes that project from the branchial arch and are involved with suspension feeding tiny prey. They are not to be confused with the gill filaments that compose the fleshy part of the gill used for gas exchange. Rakers are usually present in two rows, projecting from both the anterior and posterior side of each gill arch. Rakers are widely varied in number, spacing, and form. By preventing food particles from exiting the spaces between the gill arches, they enable the retention of food particles in filter feeders.
Integrated multi-trophic aquaculture (IMTA) is a type of aquaculture where the byproducts, including waste, from one aquatic species are used as inputs for another. Farmers combine fed aquaculture with inorganic extractive and organic extractive aquaculture to create balanced systems for environment remediation (biomitigation), economic stability and social acceptability.
Freshwater bivalves are molluscs of the order Bivalvia that inhabit freshwater ecosystems. They are one of the two main groups of freshwater molluscs, along with freshwater snails.
The oyster crab is a small, whitish or translucent crab in the family Pinnotheridae.
Mytilus is a cosmopolitan genus of medium to large-sized edible, mainly saltwater mussels, marine bivalve molluscs in the family Mytilidae.
Pseudofeces or pseudofaeces are a specialized method of expulsion that filter-feeding bivalve mollusks use in order to get rid of suspended particles such as particles of grit which cannot be used as food, and which have been rejected by the animal. The rejected particles are wrapped in mucus, and are then expelled without having passed through the digestive tract. Thus, although they may closely resemble the mollusk's real feces, they are not actually feces, hence the name pseudofeces, meaning false feces.
Forage fish, also called prey fish or bait fish, are small pelagic fish that feed on planktons and other small aquatic organisms. They are in turn preyed upon by various predators including larger fish, seabirds and marine mammals, this making them keystone species in their aquatic ecosystems.
Aquatic feeding mechanisms face a special difficulty as compared to feeding on land, because the density of water is about the same as that of the prey, so the prey tends to be pushed away when the mouth is closed. This problem was first identified by Robert McNeill Alexander. As a result, underwater predators, especially bony fish, have evolved a number of specialized feeding mechanisms, such as filter feeding, ram feeding, suction feeding, protrusion, and pivot feeding.
A planktivore is an aquatic organism that feeds on planktonic food, including zooplankton and phytoplankton. Planktivorous organisms encompass a range of some of the planet's smallest to largest multicellular animals in both the present day and in the past billion years; basking sharks and copepods are just two examples of giant and microscopic organisms that feed upon plankton.
Sabella spallanzanii is a species of marine polychaete worms in the family Sabellidae. Common names include the Mediterranean fanworm, the feather duster worm, the European fan worm and the pencil worm. It is native to shallow waters in the northeastern Atlantic Ocean and the Mediterranean Sea. It has spread to various other parts of the world and is included on the Global Invasive Species Database maintained by the IUCN.
Llanocetus is a genus of extinct toothed baleen whales from the Late Eocene of Antarctica. The type species, Llanocetus denticrenatus, reached gigantic proportions, with the juvenile specimen reaching an estimated 8 m (26 ft) in length; a second, unnamed species, known only from three isolated premolar teeth, reached an estimated total body length of up to 12 m (39 ft). Like other contemporary baleen whales of the Eocene, Llanocetus completely lacked baleen in its jaws. It was probably a suction feeder like the modern beaked and pygmy right whales.
This page is based on this Wikipedia article Text is available under the CC BY-SA 4.0 license; additional terms may apply. Images, videos and audio are available under their respective licenses.
