''Porichthys notatus'' is a species of batrachoid

toadfish Toadfish is the common name for a variety of species from several different families of fish, usually because of their toad-like appearance. "Dogfish" is a name for certain species along the gulf coast. Dolphin-Toadfish relationship Toadfish mak ...

. It is a member of the

midshipman A midshipman is an officer of the lowest rank, in the Royal Navy, United States Navy, and many Commonwealth navies. Commonwealth countries which use the rank include Canada (Naval Cadet), Australia, Bangladesh, Namibia, New Zealand, South Afr ...

genus, ''Porichthys'', and is known by the common name plainfin midshipman. It is native to the eastern

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

, where its distribution extends along the coast from

Sitka, Alaska russian: Ситка , native_name_lang = tli , settlement_type = Consolidated city-borough , image_skyline = File:Sitka 84 Elev 135.jpg , image_caption = Downtown Sitka in 1984 , image_size ...

, to

Magdalena Bay Magdalena Bay ( es, Bahía Magdalena) is a long bay in Comondú Municipality along the western coast of the Mexican state of Baja California Sur. It is protected from the Pacific Ocean by the unpopulated sandy barrier islands of Isla Magdalen ...

in southern Baja California.Froese, R. and D. Pauly, Eds
''Porichthys notatus''.
FishBase. 2011.

Description

This fish reaches up to in length. It is brownish to

olive The olive, botanical name ''Olea europaea'', meaning 'European olive' in Latin, is a species of small tree or shrub in the family Oleaceae, found traditionally in the Mediterranean Basin. When in shrub form, it is known as ''Olea europaea'' ...

iridescent Iridescence (also known as goniochromism) is the phenomenon of certain surfaces that appear to gradually change color as the angle of view or the angle of illumination changes. Examples of iridescence include soap bubbles, feathers, butterfl ...

purple dorsally, becoming lighter on the sides and yellowish/golden on the belly. Below the eye is a whitish patch and black crescent. A young individual may have a dark saddle-mark. ''P. notatus'' has wide

pectoral fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

s and a narrow but rounded tail fin.

Habitat and behavior

Except when breeding, the typical habitats for this

marine fish Saltwater fish, also called marine fish or sea fish, are fish that live in seawater. Saltwater fish can swim and live alone or in a large group called a school. Saltwater fish are very commonly kept in aquariums for entertainment. Many saltwater f ...

are sandy and muddy bottoms from shallow water just below the tide to depths of . Its diet includes

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...

s and fish. It is nocturnal, feeding at night and resting during the day, when it buries itself in the sand.Mensinger, A. F. and J. F. Case. (1991)
Bioluminescence maintenance in juvenile ''Porichthys notatus''.
''Biol Bull'' 181 181-88.

Breeding

This fish is

oviparous Oviparous animals are animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive method of most fish, amphibians, most reptiles, and all pterosaurs, dinosaurs (including birds), and ...

, and the male is dimorphic, designated as Type I and Type II. The Type I male claims a nest site, which is generally under a rock in the

intertidal zone The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species o ...

. Once the female

spawns Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquat ...

, she leaves the eggs in the care of the male and departs.Craig, P. M., et al. (2013)
Coping with aquatic hypoxia: How the plainfin midshipman (''Porichthys notatus'') tolerates the intertidal zone.
''Environ Biol Fish''. In press. One female can lay up to 400 eggs, and the number of eggs varies directly with body size. The male may mate with a few females and end up with over 1000 eggs in his nest. The eggs and

larvae 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. The ...

adhere to the wall of the nest. The male tends them by fanning them, keeping the nest clean, and hydrating them if they begin to desiccate at low tide. He protects the larvae post-hatching until they reach their juvenile stage and leave the nest, about 45 days after fertilization. Very occasionally, an egg will yield twin larvae.Stephens, R. R. (1973)
Twinning in ''Porichthys notatus'' Girard.
''Transactions of the American Fisheries Society'' 102(4) 846. Type II male is much smaller in size than the Type I. There are significantly fewer Type II males than Type I males within reproductively active populations of males, with a Type I to Type II ratio around 9:1. In contrast to Type I males, Type II males do not defend nests or guard eggs, but rather sneak in to the nest sites of Type I males and fertilize the eggs there. Type II males at times display behavior of fanning their own sperm into a nest containing a gravid female. The ratio of gonad weight to body weight of Type II males is on average nine times greater than that of Type I males. Type II males can be mistaken as gravid females as their abdomen distend due to enlarged testes. The conditions of the intertidal breeding habitat change regularly with the tide. A male that tends to his nest can become stranded as the tide recedes, even becoming beached completely out of the water. The fish tolerates this well. It can breathe air.

Physiologically Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...

, it is well adapted to

hypoxia Hypoxia means a lower than normal level of oxygen, and may refer to: Reduced or insufficient oxygen * Hypoxia (environmental), abnormally low oxygen content of the specific environment * Hypoxia (medical), abnormally low level of oxygen in the tis ...

, as well as

hypercapnia Hypercapnia (from the Greek ''hyper'' = "above" or "too much" and ''kapnos'' = "smoke"), also known as hypercarbia and CO2 retention, is a condition of abnormally elevated carbon dioxide (CO2) levels in the blood. Carbon dioxide is a gaseous pro ...

. Even its

sperm Sperm is the male reproductive cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm with a tail known as a flagellum, whi ...

are quite functional in low-oxygen conditions.

Bioluminescence

FMIB 51585 Luminous organs and lateral line of Midshipman, Porichthys notatus Girard Family Batrachoididae Monterey, California

''P. notatus'' is

bioluminescent Bioluminescence is the production and emission of light by living organisms. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some Fungus, fungi, microorganisms including ...

. It has

photophore A photophore is a glandular organ that appears as luminous spots on various marine animals, including fish and cephalopods. The organ can be simple, or as complex as the human eye; equipped with lenses, shutters, color filters and reflectors, ...

s in the

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other cuticle, animal coverings, such as the arthropod exoskeleton, have diffe ...

of its head and much of its body. One fish has over 700 photophores, each about a millimeter wide. They contain

luciferin Luciferin (from the Latin ''lucifer'', "light-bearer") is a generic term for the light-emitting compound found in organisms that generate bioluminescence. Luciferins typically undergo an enzyme-catalyzed reaction with molecular oxygen. The result ...

Norepinephrine Norepinephrine (NE), also called noradrenaline (NA) or noradrenalin, is an organic chemical in the catecholamine family that functions in the brain and body as both a hormone and neurotransmitter. The name "noradrenaline" (from Latin '' ad'', ...

activates them, producing a distinct

fluorescent Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, tha ...

green glow.Thompson, E. M., et al. (1988)
Induction of bioluminescence capability in the marine fish, ''Porichthys notatus'', by ''Vargula'' (crustacean) (¹⁴C)luciferin and unlabelled analogues.
''J. Exp. Biol.'' 137 39-51. The fish is only luminescent during courtship.Tsuji, F. I., et al. (1972)

''Nature'' 237 515-16. It may however, play a role in predator avoidance, as well. In the juvenile, photophores point ventrally, directing their illumination downwards. This helps to shadow the fish in a

silhouette A silhouette ( , ) is the image of a person, animal, object or scene represented as a solid shape of a single colour, usually black, with its edges matching the outline of the subject. The interior of a silhouette is featureless, and the silhou ...

that might make it harder for predators to see.Harper, R. D. and J. F. Case. (1999)
Disruptive counterillumination and its anti-predatory value in the plainfish midshipman ''Porichthys notatus''.
''Marine Biology'' 134 529-40. Not all individuals express this trait. There are two main populations of the species, a southern population found as far north as

San Francisco San Francisco (; Spanish language, Spanish for "Francis of Assisi, Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the List of Ca ...

, and a second population extending to the northern reaches of its range. Fish of the southern population are bioluminescent, but most northern fish are not, particularly those from the

Puget Sound Puget Sound ( ) is a sound of the Pacific Northwest, an inlet of the Pacific Ocean, and part of the Salish Sea. It is located along the northwestern coast of the U.S. state of Washington. It is a complex estuarine system of interconnected ma ...

. The nonluminescent fish lack luciferin in their photophores. In experiments, nonluminescent fish can be made luminescent by dosing them orally or by injection with luciferin obtained from the luminescent ostracod crustacean ''

Vargula hilgendorfii ''Vargula hilgendorfii'', sometimes called the sea-firefly and one of three bioluminescent species known in Japan as umi-hotaru (海蛍), is a species of ostracod crustacean. It is the only member of genus '' Vargula'' to inhabit Japanese wate ...

''. This crustacean has a similar, but not identical, luciferin compound which can apparently function in the photophores of the fish, as well. It is thought that the fish obtains its luciferin in the wild by eating this type of crustacean, perhaps a relative such as ''

Vargula tsujii ''Vargula tsujii'' is a bioluminescent cypridinid ostracod found in southern California. It feeds on dead and decaying fish and invertebrates. Vargula tsujii is an important prey item of the plainfin midshipman fish (''Porichthys notatus''), as it ...

'', and that the nonluminescent northern population does not have any of these available to them.

Vocalization

Both male and female of the species produce vocalizations. The female may produce a brief grunting sound, usually in agonistic encounters. The Type II male performs similar behaviors. The Type I male is much more vocal, both in conflict situations and in courtship. He utters long strings of shorter grunts and growls while fighting, but his courtship call is more of a prolonged

hum Hum may refer to: Science * Hum (sound), a sound produced with closed lips, or by insects, or other periodic motion * Mains hum, an electric or electromagnetic phenomenon * The Hum, an acoustic phenomenon * Venous hum, a physiological sensation ...

. He may produce this sound for over an hour at a time, reaching

frequencies Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from ''angular frequency''. Frequency is measured in hertz (Hz) which is eq ...

near 100 Hz. When a male makes the sound,

gravid In biology and human medicine, gravidity and parity are the number of times a woman is or has been pregnant (gravidity) and carried the pregnancies to a viable gestational age (parity). These terms are usually coupled, sometimes with additional te ...

females respond by moving toward him. The fish produces the sound using the muscles of its modified

swim bladder The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled Organ (anatomy), organ that contributes to the ability of many bony fish (but not cartilaginous fish) to control their buoyancy, and thus to stay at their curren ...

. It receives the sound in its

saccule The saccule is a bed of sensory cells in the inner ear. It translates head movements into neural impulses for the brain to interpret. The saccule detects linear accelerations and head tilts in the vertical plane. When the head moves verticall ...

, a sensory organ in the

inner ear The inner ear (internal ear, auris interna) is the innermost part of the vertebrate ear. In vertebrates, the inner ear is mainly responsible for sound detection and balance. In mammals, it consists of the bony labyrinth, a hollow cavity in the ...

. During the breeding season,

hormone A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior. Hormones are required ...

s induce the microscopic anatomy of the female's saccules to change in such a way that she can better sense the

harmonics A harmonic is a wave with a frequency that is a positive integer multiple of the ''fundamental frequency'', the frequency of the original periodic signal, such as a sinusoidal wave. The original signal is also called the ''1st harmonic'', the ...

of the male's calls. People in some areas are very familiar with the sound of this fish. Where there are many breeding males, the sound of many simultaneous long, loud underwater courtship calls can be clearly heard on land. In parts of

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered on ...

Hum along with male plainfin midshipman fish.
Morning Edition. National Public Radio. July 29, 2009. and in the

San Francisco Bay Area The San Francisco Bay Area, often referred to as simply the Bay Area, is a populous region surrounding the San Francisco, San Pablo, and Suisun Bay estuaries in Northern California. The Bay Area is defined by the Association of Bay Area Go ...

there are noisemaking populations. The fish is notorious in

Sausalito, California Sausalito (Spanish language, Spanish for "small willow grove") is a city in Marin County, California, Marin County, California, United States, located southeast of Marin City, California, Marin City, south-southeast of San Rafael, California ...

, where a community of people live on

houseboat A houseboat is a boat that has been designed or modified to be used primarily as a home. Most houseboats are not motorized as they are usually moored or kept stationary at a fixed point, and often tethered to land to provide utilities. How ...

s. The resident population of the fish becomes very obvious during the breeding season, when it spends the night vocalizing so loudly it keeps the houseboat residents awake.Bishop, K
Sausalito Journal; Voice of the turtle? No, toadfish love song.
''New York Times''. June 26, 1989. Its calling is most intense between midnight and 6:00 am.Sounds of the Plainfin Midshipman.
Underwater Sound from the RTC Pier. Underwater Acoustics Research Group. San Francisco State University. Despite its annoying behavior the fish inspired an affectionate local tribute in Sausalito, the Humming Toadfish Festival. The sound of the vocalization has been likened to a chorus of

kazoo The kazoo is an American musical instrument that adds a "buzzing" timbral quality to a player's voice when the player vocalizes into it. It is a type of '' mirliton'' (which itself is a membranophone), one of a class of instruments which modifi ...

B-29 The Boeing B-29 Superfortress is an American four-engined propeller-driven heavy bomber, designed by Boeing and flown primarily by the United States during World War II and the Korean War. Named in allusion to its predecessor, the B-17 Fly ...

s flying in formation, an

amplifier An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the magnitude of a signal (a time-varying voltage or current). It may increase the power significantly, or its main effect may be to boost the v ...

, a

didgeridoo The didgeridoo (; also spelt didjeridu, among other variants) is a wind instrument, played with vibrating lips to produce a continuous drone while using a special breathing technique called circular breathing. The didgeridoo was developed by ...

, "a drone of bees or maybe even the chanting of monks,"Lewis, T
'Singing' fish hums to attract mates.
LiveScience. February 19, 2013. and "an orchestra full of mournful, rasping oboes."Perlman, D
Hormones fine-tune the humming toadfish: High levels of estrogen found in the most responsive females.
''San Francisco Chronicle''. July 19, 2004.

Predators

Western Gull with Plain Fin Midshipman (Porichthys notatus)

This fish is an important prey for the

bald eagle The bald eagle (''Haliaeetus leucocephalus'') is a bird of prey found in North America. A sea eagle, it has two known subspecies and forms a species pair with the white-tailed eagle (''Haliaeetus albicilla''), which occupies the same niche as ...

in some coastal areas, being the most common food provided to eaglets by their parents in one study on

Vancouver Island Vancouver Island is an island in the northeastern Pacific Ocean and part of the Canadian Provinces and territories of Canada, province of British Columbia. The island is in length, in width at its widest point, and in total area, while are o ...

. This is a concern, however, because this fish has been found to contain relatively high levels of contaminants, such as

dioxin Dioxin may refer to: * 1,2-Dioxin or 1,4-Dioxin, two unsaturated heterocyclic 6-membered rings where two carbon atoms have been replaced by oxygen atoms, giving the molecular formula C4H4O2 *Dibenzo-1,4-dioxin, the parent compound also known as ...

. It is also prey for the

northwestern crow The American crow (''Corvus brachyrhynchos'') is a large passerine bird species of the family Corvidae. It is a common bird found throughout much of North America. American crows are the New World counterpart to the carrion crow of Europe and th ...

, the

glaucous-winged gull The glaucous-winged gull (''Larus glaucescens'') is a large, white-headed gull. The genus name is from Latin ''Larus'' which appears to have referred to a gull or other large seabird. The specific ''glaucescens'' is New Latin for " glaucous" fro ...

, and the

great blue heron The great blue heron (''Ardea herodias'') is a large wading bird in the heron family Ardeidae, common near the shores of open water and in wetlands over most of North America and Central America, as well as the Caribbean and the Galápagos ...

.Elliott, K. H., et al. (2003)
Bald Eagles, ''Haliaeetus leucocephalus'', feeding on spawning plainfin midshipman, ''Porichthys notatus'', at Crescent Beach, British Columbia.
''The Canadian Field-Naturalist'' 117(4) 601-4. It is eaten by seals and sea lions. ''P. notatus'' is host to the

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has c ...

copepod Copepods (; meaning "oar-feet") are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (inhabiting sea waters), some are benthos, benthic (living on the ocean floor) ...

s ''

Lepeophtheirus remiopsis ''Lepeophtheirus'' is a genus of sea louse. The best-known species is ''L. salmonis'', the salmon louse. Other species include '' L. pectoralis'', which uses flatfish as its host, particularly the European flounder, and is also the type ...

'' and '' Hamaticolax prolixus''.Bailly, N. (2013)
''Porichthys notatus'' Girard, 1854.
In: Froese, R. and D. Pauly, Eds. (2013). FishBase. World Register of Marine Species. Accessed on 5 June 2013.

Conservation

''P. notatus'' is not a threatened species. It is widespread and apparently not in decline.

References

{{Taxonbar, from=Q2006776 Batrachoididae Fish described in 1854