{{short description|Aquatic animal that feeds on the bottom of a body of water}} {{About|the animal|the film|Bottom Feeder}} {{redirect|Bottom Feeders|the album by Thin White Rope|Bottom Feeders (album)}} {{redirect|Bottomfeeder|the song by Amanda Palmer & The Grand Theft Orchestra|Theatre Is Evil}} {{More citations needed|date=October 2016}} [[File:Corydoras paleatus in current.jpg|thumb|A cory catfish, a commonly kept bottom feeder species in freshwater aquaria. This species is Corydoras paleatus]]
A '''bottom feeder''' is an aquatic animal that feeds on or near the bottom of a body of water.<ref name="David Suzuki Foundation">{{cite web|url=http://www.davidsuzuki.org/issues/oceans/science/marine-planning-and-conservation/bottom-feeders/|title=Bottom Feeders|publisher=David Suzuki Foundation|url-status=dead|archive-url=https://web.archive.org/web/20161028085156/http://www.davidsuzuki.org/issues/oceans/science/marine-planning-and-conservation/bottom-feeders/|archive-date=2016-10-28|access-date=2020-07-13}}</ref> Biologists often use the terms ''benthos''—particularly for invertebrates such as shellfish, crabs, crayfish, sea anemones, starfish, snails, bristleworms and sea cucumbers—and ''benthivore'' or ''benthivorous'', for fish and invertebrates that feed on material from the bottom.<ref>{{Cite journal |last1=Bergman |first1=Eva |last2=Greenberg |first2=Larry A. |date=July 1994 |title=Competition between a Planktivore, a Benthivore, and a Species with Ontogenetic Diet Shifts |url=http://doi.wiley.com/10.2307/1937449 |journal=Ecology |language=en |volume=75 |issue=5 |pages=1233–1245 |doi=10.2307/1937449|jstor=1937449 |bibcode=1994Ecol...75.1233B |url-access=subscription }}</ref> However the term ''benthos'' includes all aquatic life that lives on or near the bottom, which means it also includes non-animals, such as plants and algae.<ref name="Baustian 2015">{{cite conference|conference=Eco-DAS X Symposium Proceedings|url=https://www.carey.biol.vt.edu/wp-content/uploads/2013/09/Baustian_etal_2014.pdf|pages=25–47|last1=Baustian|first1=Melissa M.|last2=Hansen|first2=Gretchen J. A.|last3=de Kluijver|first3=Anna|last4=Robinson|first4=Kelly|last5=Henry| first5=Emily N.|last6=Knoll|first6=Lesley B.|last7=Rose|first7=Kevin C.|last8=Carey|first8=Cayelan C.|display-authors=3|publisher=Association for the Sciences of Limnology and Oceanography|date=2015|title=Linking the Bottom to the Top in Aquatic Ecosystems: Mechanisms and Stressors of Benthic-Pelagic Coupling}}</ref> Biologists also use specific terms that refer to bottom feeding fish, such as demersal fish, groundfish, benthic fish and benthopelagic fish.<ref name="Encyclopedia of Ocean Sciences">{{Cite encyclopedia|last=Bergstad|first=O. A.|title=Fish: Demersal Fish (Life Histories, Behavior, Adaptations)|date=2009|url=http://www.sciencedirect.com/science/article/pii/B9780123744739006731|encyclopedia=Encyclopedia of Ocean Sciences|edition=Second|pages=458–466|editor-last=Steele|editor-first=John H.|publisher=Academic Press|doi=10.1016/b978-012374473-9.00673-1|isbn=9780123744739|s2cid=81990196 |access-date=2020-07-13|url-access=subscription}}</ref> Examples of bottom feeding fish species groups are flatfish (halibut, flounder, plaice, sole), eels, cod, haddock, bass, carp, grouper, bream (snapper) and some species of catfish and sharks.<ref name="Encyclopedia of Ocean Sciences" />
== Feeding strategies == Many bottom feeders are detritivores,<ref name="Baustian 2015" /> taking advantage of organic materials that sink down through bodies of water to the bottom.<ref name="David Suzuki Foundation" /> In ocean environments, this downward drift of detritus is known as marine snow.<ref>Dash, Pragyan & Kashyap, Dipanjan & Mandal, Sagar. (2012). Marine snow: Its formation and significance in fisheries and aquaculture.</ref> Bottom feeders may gather detritus manually, as some crab species do; or filter microparticles out of the water using suspension feeding.<ref name="Baustian 2015" /> This biotic decomposition and recycling of organic matter is critical for the health of many aquatic environments as it helps maintain various biogeochemical cycles.<ref name="Baustian 2015" /> In 2014, it was reported that deep sea bottom feeders absorb carbon dioxide by eating creatures such as jellyfish and cephalopods, allowing the greenhouse gas to be retained at the sea floor rather than be released back into the atmosphere.<ref>{{cite news|url=https://www.livescience.com/46084-deep-sea-fish-suck-up-carbon.html|title=A New Reason to Love Bottom Feeders: They Suck Up Carbon|last=Gannon|first=Megan|date=4 June 2014|access-date=27 October 2016|publisher=Live Science}}</ref>
Other bottom feeders are herbivores or algivores that graze on living aquatic plants and macroalgae, as is the case in gastropods, chitons and some sea urchin species.<ref>Norderhaug, Kjell & Christie, H.. (2009). Sea urchin grazing and kelp re-vegetation in the NE Atlantic. Marine Biology Research - MAR BIOL RES. 5. 515-528. 10.1080/17451000902932985.</ref>
Lastly, some bottom feeders are carnivorous and specialize in either using the floor terrain as cover to ambush other animals,<ref name="Encyclopedia of Ocean Sciences" /> or scavenging from carcasses left by other predators.<ref>Mare, M. (1942). A study of a marine benthic community with special reference to the micro-organisms. ''Journal of the Marine Biological Association of the United Kingdom,'' ''25''(3), 517-554. doi:10.1017/S0025315400055132</ref> One common hunting method is the animal using body movements to stir up and conceal itself with sediment, a tactic used by many species of flatfish;<ref name="Encyclopedia of Ocean Sciences" /> or simply hide inside burrows or around other existing covers, such as many species of octopus and mantis shrimps, before suddenly emerging from cover to catch unsuspecting prey with fast strikes.<ref name="Encyclopedia of Ocean Sciences" /> Others burrow deep into the floor and hunt with most of the body remaining buried, as in the case of oceanic bobbit worms.<ref>{{cite web|publisher=Universität Basel|date=2016-09-21|title=Fish against Monster Worms|website=ScienceDaily|access-date=2020-07-13|url=https://www.sciencedaily.com/releases/2016/09/160921084602.htm}}</ref> In darker deep waters, some bottom predators uses aggressive mimicry and bioluminescence to visually lure and ambush prey, as in the case of anglerfish.
== Physiology == In fish, most bottom feeders exhibit a flat ventral region so as to more easily rest their body on the substrate.<ref name="Encyclopedia of Ocean Sciences" /> The exception may be the flatfish, which are laterally depressed but lie on their sides.<ref name="Encyclopedia of Ocean Sciences" /> Also, many exhibit what is termed an "inferior" mouth, which means that the mouth is pointed downwards; this is beneficial as their food is often going to be below them in the substrate.<ref name="Encyclopedia of Ocean Sciences" /> Those bottom feeders with upward-pointing mouths, such as stargazers, tend to seize swimming prey.<ref>Kishimoto, Hirokazu & Last, Peter & Fujii, Eiichi & Gomon, Martin. (1988). Revision of a deep-sea stargazer genus Pleuroscopus. Japanese Journal of Ichthyology. 35. 150-158. 10.1007/BF02905400.</ref> Some flatfish such as halibut actually have a "migrating" eye that moves to the upward-facing side of the fish as it ages.<ref name="Encyclopedia of Ocean Sciences" />
==Aquarium care== In the aquarium, bottom feeders are popular as it is perceived that they will clean the algae that grows in the tank. Generally, they are only useful for consuming the extra (fresh) food left by overfed or clumsy livestock; the added biomass of additional organisms means that the aquarium will likely be more dirty.<ref>{{cite journal|last=Datta|first=Subhendu|date=2012|title=Aquarium Water Quality Management|journal=Training Manual on Ornamental Fish Breeding & Culture|volume=2|pages=34–49}}</ref> Some specialized bottom feeders are more specifically sold as "algae eaters" to increase the amount of free oxygen and aesthetic appeal of a tank.<ref>Pedersen, Ole. (2011). The algal-free planted aquarium - grazing control. The Aquatic Gardener. 24. 32-39.</ref>
==See also== * Coprophagia * Demersal fish * Whitefish (fisheries term)
==References== {{Reflist}}
{{Feeding}} {{Diversity of fish}} {{wikitionary}} Category:Aquatic animals Category:Ichthyology