Sunfish
| Sunfish | ||||||||||||
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Sunfish ( Mola mola ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Mola mola | ||||||||||||
| ( Linnaeus ), 1758 |
The sunfish ( Mola mola , from Latin mola "millstone") is considered to be the heaviest bony fish in the world. The sunfish can reach a length of 3.30 meters and a mass of 2.3 tons, but mostly remains smaller and is often underestimated. Some other bony fish species, such as the European Hausen ( Huso huso ) or the strapfish Regalecus glesne , grow significantly longer.
distribution
The pelagic sunfish are found mainly in warm seas. It was found in the eastern Pacific from British Columbia to Chile , in the eastern Atlantic from Scandinavia to South Africa , in the western Atlantic from Newfoundland to Argentina . It also occurs in the Mediterranean , is common in the North Sea in autumn and swims as far as the Skagerrak and the Kattegat .
features
The body is short, disc-shaped and hardly longer than high. A normal caudal fin sitting on a caudal stalk is missing; it is regressed in the course of ontogenesis . Instead, it is replaced by a corrugated skin seam called a clavus , which closes off the blunt body and extends almost from the dorsal to the anal fin . This caudal fin shape, called gephyrocerk , is unique to sunfish and is not found in any other bony fish family.
The scaly body of the sunfish is covered by a very thick, up to 7.5 cm thick, leather-like and elastic skin (Linnaeus therefore called the genus Orthagoriscus , "piggy"). The dorsal and anal fins have the same high, triangular-pointed shape. They sit far back, symmetrically opposite each other, are the main driving force and are struck sideways synchronously with the propulsion. Both fins have a narrow base and are stiff. They cannot be folded up. The dorsal fin is supported by 15 to 18 cartilaginous fin rays, the anal fin by 14 to 17. The pectoral fins stand upwards and are round and small, pelvic fins are missing. The mouth is very small and is usually open, the teeth are fused together to form a parrot-like beak. The gill opening is reduced to a small hole above the base of the pectoral fins (recoil can be generated by squeezing out water). The skeleton of adult animals consists almost entirely of cartilage, there is no swim bladder . The back of the sunfish is brownish, gray or greenish, the flanks and the underside light.
Way of life
Sunfish live in the open ocean from the surface of the water to a depth of about 500 meters. They often stay near the surface, either swimming vertically, with the dorsal fin sticking out of the water, like a shark, or lying on their side, floating horizontally on the water surface ("basking"). The reason for this behavior has not yet been conclusively clarified. One hypothesis assumes that they regulate their body temperature again after the prey hunt in deeper and colder water zones. According to another hypothesis, they display this behavior in order to have the numerous parasites removed from their skin by cleaner fish or seabirds living near the sea surface .
Due to their size, adult animals hardly have any natural enemies. Attacks by California sea lions ( Zalophus californianus ) and orcas ( Orcinus orca ) have been reported. Remains of sunfish have also been found in the stomach of blue sharks ( Prionace glauca ) and, in one case, of a great white shark ( Carcharodon carcharias ).
food
Their food consists mainly of gelatinous organisms such as jellyfish and salps . In addition, plankton , small fish, especially eel larvae , as well as herring , small pelagic cephalopods , conch ( sea butterfly ), crustaceans , brittle stars and other marine animals eaten.
Reproduction
Sunfish are extremely fertile. A female can spawn up to 300 million eggs per spawning process, the highest number of any fish species. The eggs are one millimeter in diameter. The larvae are 3 mm long when they hatch and still have a normal caudal fin. Five long spines are supposed to protect them from predators. Through different larval stages, the first two of which are similar to those of the related ballfish and boxfish , they transform into adult animals. The spines recede in the course of development, but remain as bony remnants in the skin.
Sunfish and humans
Sunfish are rarely caught for human consumption. In Taiwan , however, the gummy meat is valued. Some parts of the fish are used in traditional Chinese medicine .
Sunfish are kept in some large show aquariums, e.g. B. in the Oceanário de Lisboa , in the L'Oceanogràfic in Valencia, in the Aquàrium de Barcelona , in the National Aquarium of Ireland in Galway, in the Monterey Bay Aquarium , in the North Sea Oceanarium in Hirtshals and temporarily in the aquarium "Open Atlantic" of the Ozeaneum in Stralsund .
literature
- Hans A. Baensch , Robert A. Patzner: Mergus Sea Water Atlas Volume 6 Non-Perciformes (Non-Perciformes) , Mergus-Verlag, Melle, ISBN 3-88244-116-X .
- Bent J. Muus, Jørgen G. Nielsen: The marine fish of Europe in the North Sea, Baltic Sea and Atlantic. Kosmos, Stuttgart 1999, ISBN 3-440-07804-3 .
- Matthias Bergbauer, Bernd Humberg: What lives in the Mediterranean? 1999, Franckh-Kosmos Verlag, ISBN 3-440-07733-0 .
Web links
- Sunfish on Fishbase.org (English)
- Pictures by Jens Kuhfs
- www.guardian.co.uk: Warm Cornish waters attract new marine life
- TED 2003 Tierney Thys on her research on sunfish
Individual evidence
- ↑ John Roach: World's Heaviest Bony Fish Discovered? National Geographic News, May 13, 2003, accessed September 13, 2014 .
- ^ A b E. C. Pope, GC Hays, TM Thys, Th. K. Doyle, DW Sims, N. Queiroz, VJ Hobson, L. Kubicek & JDR Houghton: The biology and ecology of the ocean sunfish Mola mola: a review of current knowledge and future research perspectives. In: Reviews in Fish Biology and Fisheries , Volume 20, Number 4, 2010, pp. 471-487, ( digitized ).
- ↑ Common sunfish, former holdings . Zoo animal list. Retrieved August 11, 2017.
- ↑ In the realm of the sunfish . Handelsblatt. July 6, 2009. Retrieved July 9, 2017.