Midshipman



Midshipman

Midshipman: Photo by {a href=”http://www.flickr.com/photos/noaaphotolib/5187504007/sizes/l/in/photostream/” target=”_blank”}NOAA Photo Library{/a} on Flickr.

The midshipman (Porichthys notatus) is a small fish with a large sound. Typically around 6” they inhabit mud flats and inner-tidal zones. Like freshwater carp they can breathe both in and out of water. They are “oviparous” meaning that they deposit eggs, in nests which the males tend.

These animals reached stardom in the US about 30 years ago when the extremely loud humming sound was disrupting the lives of houseboat residents in upscale Sausalito harbor, California. The alien sound was attributed to the military, to some sinister industrial project, and even to extra-terrestrials.

The sample here is produced by two males presumably ‘courting’ a female by way of swim-bladder oscillation. The phasing of their chorus (small time domain shifts over a frequency-synchronized signal) could carry some imbedded information about breeding fitness, or it could be a way of ambiguating the actual source of the signal to predators, or…?

CD Supplement to: “Sounds of the Western North Atlantic Fishes” by Fish & Mowbray, 1970. CD ©University of Rhode Island, 2001.

Latin Name:
Porichthys notatus
AKA:
Plainfin midshipman, Humming Toadfish, California Canary fish
Length:
Typical length 15 cm (6”) Max length: 38.0 cm(15”)
Weight:
Lifetime:
Physical Traits:
Olive brown to bronze or dark iridescent purple on dorsal surface, paler on sides with a golden yellow on ventral surface; white space under eye with a black crescent below; white on posterior edge of maxillary; young with a weak dark dorsal saddle.They are distinguished by having photophores (which they use to attract prey and after which they are named, reminding some of a naval uniform’s buttons) and four lateral lines.
Behavior:
nest is guarded by males, prey of seals and sea lions, can breath air out of water
Habitat:
Shallow waters, muddy bays, inter-tidal areas where they can be found under stones when the tide is out.
Locations:
Eastern Pacific: Sitka, Alaska to Magdalena Bay, southern Baja California, Mexico. Records from areas south of Baja California and in the Gulf of California are in error. Two populations exist, one from Oregon northward and the other from San Francisco southward.
Food:
crustaceans and fish
Predators:
Seals and sea lions
Links:
Wikipedia: Midshipman
Discovery of Sound in the Sea: Midshipman
FishBase.org: Midshipman
Literature:
Eschmeyer, W.N., E.S. Herald and H. Hammann 1983 A field guide to Pacific coast fishes of North America. Houghton Mifflin Company, Boston, U.S.A. 336 p.
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