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Porichthys notatus

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The plainfin midshipman (Porichthys notatus) is a species of bottom-dwelling batrachoid toadfish. It is a member of the midshipman genus, Porichthys, the only batrachoid fishes that have photophores.[2] It is native to the North American coast of the Pacific Ocean, where its distribution extends along the coast from Sitka, Alaska, to Magdalena Bay in southern Baja California.[3] There it inhabits shallow waters and will make migrations every spring to the rocky intertidal zones of the coast to breed.[4]

Porichthys notatus
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Batrachoidiformes
Family: Batrachoididae
Genus: Porichthys
Species:
P. notatus
Binomial name
Porichthys notatus
Girard, 1854

The ”midshipman” name comes from the line of photophores found on their body; they are positioned similarly to the uniforms of midshipmen—the lowest ranking naval officer of any navy. This fish is the “plainfin” in comparison to another midshipman species, the specklefin midshipman.[2]

The plainfin midshipman is known for its “singing” abilities. During breeding, both male and female fish will vocalize to attract mates. The sound is well-known among houseboat residents and has earned the fish nicknames of the “California singing fish,” or the “Humming Toadfish,” as well as becoming the namesake for The Sausalito Humming Toadfish Festival.[5]

Description

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This fish reaches up to 38 cm (15 in) in length, and is one of the largest of the Porichthys toadfishes. It is brownish to olive to iridescent purple dorsally, becoming lighter on the sides and yellowish/golden on the belly, though this can depend on sex. Below the eye is a whitish patch and black crescent. Adults usually lack saddle-marks, but there are 6-7 saddle-marks if they are present. A young individual looks like an adult but may have a few dark saddle-marks. P. notatus has wide pectoral fins and a narrow but rounded tail fin.[3] There are four lateral lines on the head and sides of the body.[2]

 
Adult plainfin midshipman

It has 33-38 soft rays in the long second dorsal fin, 30-35 anal rays, and 17 - 20 pectoral rays.[2] The length of the fish varies from female to males. It is distinguished from other fish in its genus by the positioning of its photophores. All Porichthys have a series of photophores along the sides and bottoms of its body: the branchiostegal, gastric, gular, lateral, mandibular, pleural, and ventral photophores. In the plainfin midshipman, the branchiostegal photophore series is V-shaped.  The pleural photophore series ends posterior to the pleural lateral line (it shares this with the specklefin and mimetus midshipmen).[2]

The plainfin midshipman is both sexually dimorphic and dimorphic between the two males (two different morphs that correspond to different breeding styles; see Breeding). Females can range from 9.6 – 15.2 cm in standard length and can weigh 11.1 – 47.3 g. Type I males measure 12.0 cm – 21.0 cm in standard length and can weigh 30 – 206 g. On the other hand, Type II males weigh 3.9-17.3g, and measure 6.5-10.5 cm in standard length.[2][6] However, all sexes experience annual fluctuations in body size; for example, body mass peaks for Type I males during pre-nesting season.[7]

Similar species include:

  • Specklefin midshipman (Porichthys myriaster), which differs from the plainfin by bands on its caudal fin that the plainfin lacks and U-shaped branchiostegal photophore series. This is the only other Porichthys species with which the P. notatus overlaps.[2]
  • Mimetus midshipman (Porichthys mimetus), which differs from the plainfin in that it has 32-36 second dorsal rays instead of 33-38 in the plainfin, as well as.[2]

Habitat and behavior

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During the nonbreeding season, the plainfin midshipmen typically inhabit moderately deep ocean waters off the coast of Pacific coast of North America, from Canada to Baja California. They can range from shallow water just below the tide to depths of 366 m and prefer sandy and muddy bottoms.[1][3][8]

Diet

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Its diet includes crustaceans and fish.[3] It is nocturnal, feeding at night and resting during the day, when it buries itself in the sand.[9] As juvenile, they feed on small crustacean larvae and zooplankton.[8]

 
Plainfin midshipman eggs.

Breeding

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During the late spring and early summer, they migrate from the depths to the intertidal zones of the coast to breed. For example, in Monterey, California, they come from canyons to seek outcroppings in shallow intertidal zones.[10] They can be found by lifting up rocks or logs in the intertidal zones during this season.[4]

This fish is oviparous, and the male is dimorphic, designated as Type I and Type II.[11] The Type I male claims a nest site, which is generally under a rocks or boulders in the intertidal zone. Once underneath, he digs out a cavity using his pectoral fins. A female will come seeking out males—attracted by his vocalizations—to deposit her eggs in his cavity.[8] He will then fertilize the eggs. One female normally lays 200-400 eggs, and the number of eggs varies directly with body size.[12] The male may attract more than one female and end up with over 1000 eggs in his nest.[9] The female deposits the eggs in a single layer to the upper wall of the nest.[3][8] Once the female spawns, she leaves the eggs in the care of the male and departs.[13] 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.[13] Very occasionally, an egg will yield twin larvae.[14] Type II male is much smaller in size than the Type I.[13] 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.[11] 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.[11] Type II males at times display behavior of fanning their own sperm into a nest containing a gravid female.[15] The ratio of gonad weight to body weight of Type II males is on average nine times greater than that of Type I males.[11] Type II males can be mistaken as gravid females as their abdomen distend due to enlarged testes.[11]

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 by elevating their hematocrit levels and tolerating high lactate levels.[13][16] It can "breathe" air.[17][18][3] Physiologically, it is well adapted to hypoxia, as well as hypercapnia. Even its sperm are quite functional in low-oxygen conditions.[13]

The eggs take about 16-20 to incubate. After hatching, the embryos remain attached to the cavity wall by the yolk sacs for about a month, after which they will detach and bury in the mud. The juveniles are still nocturnal and will bury in the mud during the day and feed at night. They will gradually make their way back to the water.[8]

Bioluminescence

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Drawing showing position of luminous organs and lateral line
 
Adult plainfin midshipman with photophores visible.

P. notatus is bioluminescent. It has photophores in the skin of its head and much of its body. One fish has over 700 photophores, each about a millimeter wide. They contain luciferin. Norepinephrine activates them, producing a distinct fluorescent green glow.[19] The fish is only luminescent during courtship.[20] It may however, play a role in predator avoidance and potentially attracting prey, as well. In the juvenile, photophores point ventrally, directing their illumination downwards. This helps to shadow the fish in a silhouette that might make it harder for predators to see.[21]

Not all individuals express this trait. There are two main populations of the species, a southern population found as far north as San Francisco, and a second population extending to the northern reaches of its range.[3] Fish of the southern population are bioluminescent, but most northern fish are not,[19] particularly those from the Puget Sound.[20] The nonluminescent fish lack luciferin in their photophores.[19] 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. 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, and that the nonluminescent northern population does not have any of these available to them.[19][22]

Vocalization

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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 to the female. 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.[23] This sound is only produced at night. He may produce this sound for over an hour at a time, reaching frequencies near 98-106 Hz.[24][25] When a male makes the sound, gravid females respond by moving toward him.[26]

 
Side view of a plainfin midshipman fish.

The fish produces the sound using the muscles of its modified swim bladder.[24] It receives the sound in its saccule, a sensory organ in the inner ear. During the breeding season, hormones induce the microscopic anatomy of the female's saccules to change in such a way that she can better sense the harmonics of the male's calls.[23]

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[27] and in the San Francisco Bay Area there are noisemaking populations. The fish is notorious in Sausalito, California, where a community of people live on houseboats. 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.[28] Its calling is most intense between midnight and 6:00 a.m.[29] Despite its annoying behavior the fish inspired an affectionate local tribute in Sausalito, the Humming Toadfish Festival.[28]

The sound of the vocalization has been likened to a chorus of kazoos, B-29s flying in formation,[28] an amplifier, a didgeridoo, "a drone of bees or maybe even the chanting of monks,"[30] and "an orchestra full of mournful, rasping oboes."[31]

Predators

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Western gulls and other birds will catch and eat plainfin midshipman

It is eaten by seals, sea lions, otters, mink, crustaceans, fish, etc.[3][32] This fish is an important prey for the bald eagle in some coastal areas, being the most common food provided to eaglets by their parents in one study on Vancouver Island. This is a concern, however, because this fish has been found to contain relatively high levels of contaminants, such as dioxin. It is also prey for the northwestern crow, the glaucous-winged gull, and the great blue heron.[33]

P. notatus is host to the parasitic copepods Lepeophtheirus remiopsis and Hamaticolax prolixus.[34]

Conservation

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P. notatus is not a threatened species. It is widespread and apparently not in decline.[1]

References

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  1. ^ a b c Collette, B.; Acero, A.; Betancur, R.; Cotto, A.; Rojas, P. (2010). "Porichthys notatus". IUCN Red List of Threatened Species. 2010: e.T183724A8165351. doi:10.2305/IUCN.UK.2010-3.RLTS.T183724A8165351.en. Retrieved 19 November 2021.
  2. ^ a b c d e f g h Walker, H. J.; Rosenblatt, R. H. (1988-12-28). "Pacific Toadfishes of the Genus Porichthys (Batrachoididae) with Descriptions of Three New Species". Copeia. 1988 (4): 887. doi:10.2307/1445712. JSTOR 1445712.
  3. ^ a b c d e f g h Froese, R. and D. Pauly, Eds. Porichthys notatus. FishBase. 2011.
  4. ^ a b Gilbert, Carter R. (1968). "Western Atlantic batrachoidid fishes of the genus Porichthys, including three new species". Bulletin of Marine Science. 18 (3): 671–730.
  5. ^ "The Humming Toadfish of Sausalito, California". Covering the City. Retrieved 2024-11-13.
  6. ^ Brantley, Richard K.; Bass, Andrew H. (1994-01-12). "Alternative Male Spawning Tactics and Acoustic Signals in the Plainfin Midshipman Fish Porichthys notatus Girard (Teleostei, Batrachoididae)". Ethology. 96 (3): 213–232. doi:10.1111/j.1439-0310.1994.tb01011.x. ISSN 0179-1613.
  7. ^ Sisneros, J. A.; Alderks, P. W.; Leon, K.; Sniffen, B. (January 2009). "Morphometric changes associated with the reproductive cycle and behaviour of the intertidal-nesting, male plainfin midshipman Porichthys notatus". Journal of Fish Biology. 74 (1): 18–36. doi:10.1111/j.1095-8649.2008.02104.x. ISSN 0022-1112. PMID 20735522.
  8. ^ a b c d e Arora, Harbans Lall (1948-06-30). "Observations on the Habits and Early Life History of the Batrachoid Fish, Porichthys notatus Girard". Copeia. 1948 (2): 89–93. doi:10.2307/1438409. JSTOR 1438409.
  9. ^ a b Mensinger, A. F.; Case, J. F. (August 1991). "Bioluminescence Maintenance in Juvenile Porichthys notatus". The Biological Bulletin. 181 (1): 181–188. doi:10.2307/1542501. ISSN 0006-3185. JSTOR 1542501. PMID 29303651.
  10. ^ Elkhorn Slough Foundation (2012-12-06). The Plainfin Midshipman. Retrieved 2024-11-13 – via YouTube.
  11. ^ a b c d e Bass, Andrew (1992-04-01). "Dimorphic male brains and alternative reproductive tactics in a vocalizing fish". Trends in Neurosciences. 15 (4): 139–145. doi:10.1016/0166-2236(92)90356-D. ISSN 0166-2236. PMID 1374972. S2CID 31850449.
  12. ^ DeMartini, Edward E. (1990-09-19). "Annual Variations in Fecundity, Egg Size and Condition of the Plainfin Midshipman (Porichthys notatus)". Copeia. 1990 (3): 850–855. doi:10.2307/1446452. JSTOR 1446452.
  13. ^ a b c d e 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.
  14. ^ Stephens, R. R. (1973). Twinning in Porichthys notatus Girard. Transactions of the American Fisheries Society 102(4) 846.
  15. ^ Bass, Andrew H. (1993-06-01). "From brains to behaviour: hormonal cascades and alternative mating tactics in teleost fishes". Reviews in Fish Biology and Fisheries. 3 (2): 181–186. Bibcode:1993RFBF....3..181B. doi:10.1007/BF00045231. ISSN 1573-5184. S2CID 114817.
  16. ^ Craig, Paul M.; Fitzpatrick, John L.; Walsh, Patrick J.; Wood, Chris M.; McClelland, Grant B. (February 2014). "Coping with aquatic hypoxia: how the plainfin midshipman (Porichthys notatus) tolerates the intertidal zone". Environmental Biology of Fishes. 97 (2): 163–172. doi:10.1007/s10641-013-0137-3. ISSN 0378-1909.
  17. ^ Martin, K. L. M. (1993). "Aerial release of CO2 and respiratory exchange ratio in intertidal fishes out of water". Environmental Biology of Fishes. 37 (2): 189–196. Bibcode:1993EnvBF..37..189M. doi:10.1007/BF00000594. S2CID 34804496.
  18. ^ Martin, K. L. M.; Bridges, C. R. (1998). "Respiration in water and air". In Horn, M. H.; Martin, K. L. M.; Chotkowski, M. A. (eds.). Intertidal Fishes: Life in Two Worlds. Elsevier. pp. 54–78. ISBN 978-008053493-0.
  19. ^ a b c d 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.
  20. ^ a b Tsuji, F. I., et al. (1972). Bioluminescence in the marine teleost, Porichthys notatus, and its induction in a non-luminous form by Cypridina (ostracod) luciferin. (Letter). Nature 237 515-16.
  21. ^ 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.
  22. ^ Thompson, E. M.; Tsuji, F. I. (August 1989). "Two populations of the marine fish Porichthys notatus, one lacking in luciferin essential for bioluminescence". Marine Biology. 102 (2): 161–165. doi:10.1007/BF00428276. ISSN 0025-3162.
  23. ^ a b Sisneros JA (April 2007). "Saccular potentials of the vocal plainfin midshipman fish, Porichthys notatus". Journal of Comparative Physiology A. 193 (4): 413–24. doi:10.1007/s00359-006-0195-5. PMC 2582148. PMID 17143623.
  24. ^ a b Forbes JG, Morris HD, Wang K (April 2006). "Multimodal imaging of the sonic organ of Porichthys notatus, the singing midshipman fish". Magnetic Resonance Imaging. 24 (3): 321–31. doi:10.1016/j.mri.2005.10.036. PMID 16563962.
  25. ^ Ibara, Richard M.; Penny, Larry T.; Ebeling, Alfred W.; van Dykhuizen, Gilbert; Cailliet, Gregor (1983), Noakes, David L. G.; Lindquist, David G.; Helfman, Gene S.; Ward, Jack A. (eds.), "The mating call of the plainfin midshipman fish, Porichthys notatus", Predators and prey in fishes: Proceedings of the 3rd biennial conference on the ethology and behavioral ecology of fishes, held at Normal, Illinois, U.S.A., May 19–22, 1981, Dordrecht: Springer Netherlands, pp. 205–212, doi:10.1007/978-94-009-7296-4_22, ISBN 978-94-009-7296-4, retrieved 2024-11-13
  26. ^ Zeddies DG, Fay RR, Alderks PW, Shaub KS, Sisneros JA (May 2010). "Sound source localization by the plainfin midshipman fish, Porichthys notatus". The Journal of the Acoustical Society of America. 127 (5): 3104–13. Bibcode:2010ASAJ..127.3104Z. doi:10.1121/1.3365261. PMID 21117759.
  27. ^ Hum along with male plainfin midshipman fish. Morning Edition. National Public Radio. July 29, 2009.
  28. ^ a b c Bishop, K. Sausalito Journal; Voice of the turtle? No, toadfish love song. New York Times. June 26, 1989.
  29. ^ Sounds of the Plainfin Midshipman. Underwater Sound from the RTC Pier. Underwater Acoustics Research Group. San Francisco State University.
  30. ^ Lewis, T. 'Singing' fish hums to attract mates. LiveScience. February 19, 2013.
  31. ^ Perlman, D. Hormones fine-tune the humming toadfish: High levels of estrogen found in the most responsive females. San Francisco Chronicle. July 19, 2004.
  32. ^ Cullis-Suzuki, Sarika (2016), Popper, Arthur N.; Hawkins, Anthony (eds.), "Singing Fish in an Ocean of Noise: Effects of Boat Noise on the Plainfin Midshipman (Porichthys notatus) in a Natural Ecosystem", The Effects of Noise on Aquatic Life II, Advances in Experimental Medicine and Biology, vol. 875, New York, NY: Springer New York, pp. 171–179, doi:10.1007/978-1-4939-2981-8_20, ISBN 978-1-4939-2980-1, PMID 26610957, retrieved 2024-11-13
  33. ^ 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.
  34. ^ 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.
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