Northern boatswain fish
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Northern boatswain fish ( Porichthys notatus ) |
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| Porichthys notatus | ||||||||||||
| Girard , 1854 |
The northern boatswain fish ( Porichthys notatus ) is a member of the frogfish (Batrachoididae) that occurs on the Pacific coast of North America from Alaska to Baja California . There are two separate populations, one near Oregon and north of it, the other south of San Francisco . Only a few specimens have been sighted in the intermediate zone.
features
The northern boatswain fish is up to 38 cm long and is from olive-brown to bronze in color. Some specimens shimmer purple on the upper side, the underside is light, sometimes also golden yellow. There is a white, arcuate spot under the eye, and a black one underneath. Young fish have a hazy, dark, saddle-shaped spot on their back. The pectoral fins are broad, the caudal fin small and rounded. In contrast to Porichthys myriaster , the fins are not spotted. The number of Branchiostegal rays is six. The light organs on the underside of the head are arranged in a V-shape.
Fin formula : dorsal II / 33–37, anal 30–35.
Way of life
Northern boatswain fish live from the intertidal zone, where adult animals can survive the ebb out of the water, hidden under stones and seaweed and breathing air, down to depths of less than 350 meters on sandy and muddy bottoms. Adult boatswain fish make vertical migrations at night. They feed on crustaceans and small fish. They are oviparous . Spawning takes place mainly in bays. The clutch is guarded by the male in a nest made of stones.
Boatswain fish are an important food for California sea lions and seals .
Lute
During the spawning season, the male of the northern boatswain fish attracts females with a loud hum and tries to encourage them to lay eggs. If some males are relatively close together, this hum can even make boat walls vibrate. So that the boatswain fish is not deaf or hearing impaired, whether it is courting its own call, the sound production and the sense of hearing are controlled by the same brain region. While he creates an audible vibrato (approx. 100 Hz) with his swim bladder , a signal is sent to the hair cells of his ear at the same time, which significantly reduces their sensitivity to noise.
The courtship call can only attract females who have fertile eggs. This has to do with the fact that female boatswain fish “open their ears” only when their estrogen levels are elevated . The females seek out males who hum particularly loudly and for a long time (up to an hour), which again indicates their hormonal status.
literature
- Eschmeyer, Herald, Hamann: Pacific Coast Fishes , Peterson Field Guides, ISBN 0-395-33188-9
Individual evidence
- ↑ Andreas von Bubnoff: Humming fish solves noisy clash. Nature , doi : 10.1038 / news050711-1
- ↑ Hormones fine-tune the humming toadfish by David Perlman, July 2004 (English)
Web links
- Northern Boatswain Fish on Fishbase.org (English)
- Porichthys notatus inthe IUCN 2013 Red List of Threatened Species . Posted by: Collette, B., Acero, A., Betancur, R., Cotto, A. & Rojas, P., 2007. Retrieved January 27, 2014.
- Sounds of the Plainfin Midshipman (Porichthys notatus). San Francisco State University (English, with sound samples)