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{{short description, Obtaining nutrients by consuming algae Algophagy is a feeding
behaviour Behavior (American English) or behaviour ( British English) is the range of actions and mannerisms made by individuals, organisms, systems or artificial entities in some environment. These systems can include other systems or organisms as w ...
whereby an animal eats
algae Algae ( , ; : alga ) are any of a large and diverse group of photosynthetic, eukaryotic organisms. The name is an informal term for a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from ...
as a food source.Deonier, D. L. (1972). Observations on mating, oviposition, and food habits of certain shore flies (Diptera: Ephydridae). Algae is a group of
photosynthetic Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in ...
organisms that mostly rely on aquatic environments. They grow low to the ground as they lack vascular tissue, an adaptation postdating their origin. While the group of algal species is large, it is generally accepted that algae is high in nutritional value and often contain a variety of concentrated vitamins and minerals. Algophagy as a feeding behaviour was first noted in literature by Deonier (1972) in their explanation of feeding habits of shore flies (
Ephydridae Ephydridae (shore fly, sometimes brine fly) is a family of insects in the order Diptera. Shore flies are tiny flies that can be found near seashores or at smaller inland waters, such as ponds. About 2,000 species have been described worldwide, i ...
)''.'' In this context, this term was used to describe the behaviour of these flies consuming and digesting algal matter. This feeding style has also been noted in other animals in recent literature. While this behaviour has been noted in a variety of insects (specifically '' Ameletus'' mayflies), it has also been observed in other
invertebrates Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...
such as the crab ''
Carcinus maenas ''Carcinus maenas'' is a common littoral crab. It is known by different names around the world. In the British Isles, it is generally referred to as the shore crab, or green shore crab. In North America and South Africa, it bears the name eur ...
'' and the ''Nanorchestes'' mite. Additionally, this behaviour has been noted in
vertebrates Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, wi ...
such as the chimpanzee ''
Pan troglodytes The chimpanzee (''Pan troglodytes''), also known as simply the chimp, is a species of great ape native to the forest and savannah of tropical Africa. It has four confirmed subspecies and a fifth proposed subspecies. When its close relative the ...
,'' the sheep ''
Ovis aries Sheep or domestic sheep (''Ovis aries'') are domesticated, ruminant mammals typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus ''Ovis'', in everyday usage it almost always refers to domesticated s ...
,'' and the chicken ''
Gallus gallus domesticus The chicken (''Gallus gallus domesticus'') is a domesticated junglefowl species, with attributes of wild species such as the grey and the Ceylon junglefowl that are originally from Southeastern Asia. Rooster or cock is a term for an adult m ...
.'' This feeding behaviour has more recently been adopted by
humans Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...
as well.


Examples in invertebrates

Algophagy is a feeding behaviour found commonly amongst many invertebrate species. Some examples of these observations include the mayfly, mites, and certain species of crab.
Mayflies Mayflies (also known as shadflies or fishflies in Canada and the upper Midwestern United States, as Canadian soldiers in the American Great Lakes region, and as up-winged flies in the United Kingdom) are aquatic insects belonging to the order ...
are a group of
insects Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs ...
found to feed off of epilithic algae from near streams in
New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe, New Mexico, Santa Fe , LargestCity = Albuquerque, New Mexico, Albuquerque , LargestMetro = Albuquerque metropolitan area, Tiguex , Offi ...
,
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five ma ...
. In a study to examine
ingestion Ingestion is the consumption of a substance by an organism. In animals, it normally is accomplished by taking in a substance through the mouth into the gastrointestinal tract, such as through eating or drinking. In single-celled organisms ingest ...
and
digestion Digestion is the breakdown of large insoluble food molecules into small water-soluble food molecules so that they can be absorbed into the watery blood plasma. In certain organisms, these smaller substances are absorbed through the small intest ...
of algae by
larval A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. T ...
insects, Peterson (1998) analyzed the fecal composition of varying insect larvae and
nymphs A nymph ( grc, νύμφη, nýmphē, el, script=Latn, nímfi, label=Modern Greek; , ) in ancient Greek folklore is a minor female nature deity. Different from Greek goddesses, nymphs are generally regarded as personifications of nature, are ty ...
. All species studied showed epilithic algae in their fecal matter, markedly in the multiple species of mayfly. This study outlines the feeding behaviours used by specifically the '' Ameletus'' mayflies to feed off of and digest algae as a source of food. This behaviour has also been noted in species of mites. The ''Nanorchestes''
mite Mites are small arachnids (eight-legged arthropods). Mites span two large orders of arachnids, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari, but genetic analysis does not show clear evid ...
is a small invertebrate of the genus ''Pachygnathoid'' that lives in the ground and is often found in
extremophilic An extremophile (from Latin ' meaning "extreme" and Greek ' () meaning "love") is an organism that is able to live (or in some cases thrive) in extreme environments, i.e. environments that make survival challenging such as due to extreme temper ...
conditions. Krantz and Lindquist (1979) made observations of these mites feeding and surviving off of
green algae The green algae (singular: green alga) are a group consisting of the Prasinodermophyta and its unnamed sister which contains the Chlorophyta and Charophyta/ Streptophyta. The land plants ( Embryophytes) have emerged deep in the Charophyte alg ...
, while also delving into the background theory behind this. The authors argue that algal
microflora Microbiota are the range of microorganisms that may be commensal, symbiotic, or pathogenic found in and on all multicellular organisms, including plants. Microbiota include bacteria, archaea, protists, fungi, and viruses, and have been fo ...
predates that of
vascular plants Vascular plants (), also called tracheophytes () or collectively Tracheophyta (), form a large group of land plants ( accepted known species) that have lignified tissues (the xylem) for conducting water and minerals throughout the plant. They a ...
, a step to understanding the evolutionary pathway that follows algophagy. Because of this flora timeline, the mites relied on algae as an early source of nutrition. Algophagy also occurs in certain species of crab. The
green crab ''Carcinus maenas'' is a common littoral crab. It is known by different names around the world. In the British Isles, it is generally referred to as the shore crab, or green shore crab. In North America and South Africa, it bears the name eu ...
is a highly
invasive species An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species adv ...
found on nearly all continents of Earth. This
littoral The littoral zone or nearshore is the part of a sea, lake, or river that is close to the shore. In coastal ecology, the littoral zone includes the intertidal zone extending from the high water mark (which is rarely inundated), to coastal areas ...
crab is an
omnivore An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nut ...
with a large array of preferred foods, forming an important ecological connection with many ocean environments. In a study performed by Ropes (1968), 3,979 green crabs were sampled and their gut contents were analyzed to reveal that algae was one of the two consumed plant foods. This was replicated in other studies such as that of Baeta, Cabral, Marques, and Pardal (2006) who also found these results nearly 40 years later.


Examples in non-human vertebrates

Algophagy has been observed in a variety of vertebrate species, such as the chimpanzee, species of sheep, and also in the common chicken. The chimpanzee is a
primate Primates are a diverse order (biology), order of mammals. They are divided into the Strepsirrhini, strepsirrhines, which include the lemurs, galagos, and lorisids, and the Haplorhini, haplorhines, which include the Tarsiiformes, tarsiers and ...
in the same family as humans and are native to sub-Saharan Africa. While many chimpanzees are naturally
hydrophobic In chemistry, hydrophobicity is the physical property of a molecule that is seemingly repelled from a mass of water (known as a hydrophobe). In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be nonpolar and, ...
, Sakamaki (1998) found that those in Mahale have been observed to submerge themselves into freshwater and eat algae. This observation is the first documentation of a primate using algae in the wild as a food source and is an important marker of possible adaptation in the species. While the chimpanzee in question, Sally, was one of the only algae-eaters in her group, it was assumed that she had adopted this behaviour from her natal group prior to immigrating to this new environment. Nonetheless, this
anecdotal Anecdotal evidence is evidence based only on personal observation, collected in a casual or non-systematic manner. The term is sometimes used in a legal context to describe certain kinds of testimony which are uncorroborated by objective, independ ...
field study highlights the act of eating algae in chimpanzees. Another example here is found in certain species of sheep. The
North Ronaldsay sheep The North Ronaldsay or Orkney is a breed of sheep from North Ronaldsay, the northernmost island of Orkney, off the north coast of Scotland. It belongs to the Northern European short-tailed sheep group of breeds, and has evolved without much c ...
is native to the island of
Orkney Orkney (; sco, Orkney; on, Orkneyjar; nrn, Orknøjar), also known as the Orkney Islands, is an archipelago in the Northern Isles of Scotland, situated off the north coast of the island of Great Britain. Orkney is 10 miles (16 km) nort ...
off of
Scotland Scotland (, ) is a country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a border with England to the southeast and is otherwise surrounded by the Atlantic Ocean to th ...
and had been bred for wool until recently being listed as a vulnerable population. This species relies heavily on
tidal Tidal is the adjectival form of tide. Tidal may also refer to: * ''Tidal'' (album), a 1996 album by Fiona Apple * Tidal (king), a king involved in the Battle of the Vale of Siddim * TidalCycles, a live coding environment for music * Tidal (servic ...
algae as outlined by Paterson and Coleman (1982). The researchers here observed the sheep feeding largely on
brown algae Brown algae (singular: alga), comprising the class Phaeophyceae, are a large group of multicellular algae, including many seaweeds located in colder waters within the Northern Hemisphere. Brown algae are the major seaweeds of the temperate an ...
, commonly known as
seaweed Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, marine algae. The term includes some types of ''Rhodophyta'' (red), ''Phaeophyta'' (brown) and ''Chlorophyta'' (green) macroalgae. Seaweed species such as ke ...
. The sheep relied on the tides to expose the nutrient rich algae and when the tides made the food inaccessible, the sheep supported their diet with other forms of
grazing In agriculture, grazing is a method of animal husbandry whereby domestic livestock are allowed outdoors to roam around and consume wild vegetations in order to convert the otherwise indigestible (by human gut) cellulose within grass and other ...
. Algophagy also been observed in the common chicken as well. When the Poultry Department of the
University of Maryland The University of Maryland, College Park (University of Maryland, UMD, or simply Maryland) is a public university, public Land-grant university, land-grant research university in College Park, Maryland. Founded in 1856, UMD is the Flagship un ...
did an
assay An assay is an investigative (analytic) procedure in laboratory medicine, mining, pharmacology, environmental biology and molecular biology for qualitatively assessing or quantitatively measuring the presence, amount, or functional activity of ...
of dried ''
Chlorella pyrenoidosa ''Auxenochlorella pyrenoidosa'', formerly ''Chlorella pyrenoidosa'', is a species of the freshwater green alga in the Division Chlorophyta. It occurs worldwide. The species name ''pyrenoidosa'' refers to the presence of a prominent pyrenoid withi ...
'', they found it to be a rich nutrient source that could be substituted into the diet of chickens. The researcher behind this outlined the benefits of using this food replacement for chickens in that it improved growth and wellbeing of the chicken. While this example is not a natural one, it does outline the use of algae as a food source for domestic chickens, an important consideration in the future of both algophagy and
agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled peop ...
.


Algophagy in humans

While this feeding behaviour is not commonly associated with
human evolution Human evolution is the evolutionary process within the history of primates that led to the emergence of ''Homo sapiens'' as a distinct species of the hominid family, which includes the great apes. This process involved the gradual development o ...
or adaptation, it has gained some momentum in recent application. New dieting and food trends have veered towards the inclusion of spirulina into supplements. Spirulina is a bacterium, but mostly referred to as
blue-green algae Cyanobacteria (), also known as Cyanophyta, are a phylum of gram-negative bacteria that obtain energy via photosynthesis. The name ''cyanobacteria'' refers to their color (), which similarly forms the basis of cyanobacteria's common name, blue ...
, that is used to supplement a variety of nutrients including essential
proteins Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respondi ...
,
vitamins A vitamin is an organic molecule (or a set of molecules closely related chemically, i.e. vitamers) that is an essential micronutrient that an organism needs in small quantities for the proper functioning of its metabolism. Essential nutrie ...
, and
minerals In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. ( ...
. In a past review of spirulina by Belay, Ota, Miyakawa, and Shimamatsu (1993), it was outlined that the algae could even be correlated to reduced risk of cholesterol problems, cancer, and heavy metal nephrotoxicity.Belay, A., Ota, Y., Miyakawa, K., & Shimamatsu, H. (1993). Current knowledge on potential health benefits of Spirulina. Journal of applied Phycology, 5(2), 235–241. Spirulina is relatively popular among dietary supplement enthusiasts and can be used in a varied of forms from capsules, to smoothies, to baked goods. This outlines a contemporary example of algophagy in humans.


See also

*
Glossary of entomology terms This glossary of entomology describes terms used in the formal study of insect species by entomologists. A–C A synthetic chlorinated hydrocarbon insecticide, toxic to vertebrates. Though i ...
* Eating behaviour in Insects *
Animal behaviour Ethology is the scientific study of animal behaviour, usually with a focus on behaviour under natural conditions, and viewing behaviour as an evolutionarily adaptive trait. Behaviourism as a term also describes the scientific and objective ...
*
Feeding behaviour Feeding is the process by which organisms, typically animals, obtain food. Terminology often uses either the suffixes -vore, -vory, or -vorous from Latin ''vorare'', meaning "to devour", or -phage, -phagy, or -phagous from Greek φαγ� ...


References

Eating behaviors