Trachinus draco

Trachinus draco

Cladus: Eukaryota
Supergroup: Opisthokonta
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclassis: Osteichthyes
Classis: Actinopterygii
Subclassis: Neopterygii
Infraclassis: Teleostei
Superordo: Acanthopterygii
Ordo: Perciformes
Subordo: Trachinoidei
Familia: Trachinidae
Genus: Trachinus
Species: Trachinus draco

Name

Trachinus L., 1758

--------

The greater weever, Trachinus draco, is a weever fish of the family Trachinidae. It is less common than the lesser weever.


Description

Its body is a greenish yellow or lime, to dark green and brown, on the head and back, with pale sides, and with yellowish to bluish-brown oblique lines.

The greater weever's body is elongate, tapered and laterally compressed, with a large head. Its length is up to six times its height. The upper rim of the eye has two to three small open spines, in front of each eye.

The mouth is huge and is set obliquely. The eyes are placed toward the top of the head. The dorsal fin is blackish. The second dorsal fin and anal fins have a yellow stripe running their length.

Its pectoral fin is rounded with a notch. On the first dorsal fin, both of the spines, and those of the gill covers, have venom glands attached to them. The spines are grooved, and when pressed, toxin is driven up the grooves.

A male unsexed fish's average size is 53 centimeters (20.9 in). It weighs about 1.86 kilograms (4 lb).
Greater weever

Sting mechanism

The interaction of two muscles (flexor and extensor) attached to the plate opercularis increases the exposed portion of the spine to facilitate the injection of venom. These two muscles are antagonistic, the contraction of one erects the spine, and thus increases its exposed portion such that the membrane surrounding the spine is not elastic, while the contraction of the other reduces the size of the exposed portion. The length of the exposed part of the spine depends on the angle of the opening of the cover.

The outer membrane of the spine presses on the venom gland during the contraction of the flexor muscle, ejecting the venom along the spine.

First aid for stings follows the general pattern for treatment of all weever stings.

Reproduction

Spawning begins in June and August. Pelagic eggs are 1 millimeters (0 in). Breeding season is from June to August.

Range and habitat

It inhabits the Eastern Atlantic, in the area 66° N - 27° N, 19° W - 42° E. It ranges from Norway to Morocco, Madeira and the Canary Islands, including the Mediterranean and the Black Seas. It also lives in all waters of the United Kingdom. It prefers a temperate Climate.

The greater weever, like the lesser weever, lives on muddy, sandy or gravelly bottoms, at depths up to about 150 meters (492 ft). It usually rests on the bottom, often with eyes closed, exposing the tip of the first dorsal fin. They feed at night, pelagically, feeding on crustaceans, shrimps and crabs, as well as smaller fish.

Importance to humans

The greater weever has minor commercial importance, and is a gamefish. It can be found in aquariums, mainly those that are public. This weever has medium resilience. The minimum population (that is doubling) time 1.4 to 4.4 years (assuming tm=2-4).

It is eaten fresh or frozen, can be fried, broiled, boiled and baked.

As sport

The UK Record Weights from rod/line from shore is

References

* "Greater Weever". http://web.ukonline.co.uk/aquarium/pages/greaterweever.html. Retrieved 2006-09-22.
* Auerbach, Campbell, P.S., Dr.. "Greater Weever Species Summary". http://web.ukonline.co.uk/aquarium/pages/greaterweever.html. Retrieved 2006-09-22.

Biology Encyclopedia

Fish Images

Source: Wikipedia, Wikispecies: All text is available under the terms of the GNU Free Documentation License

Index

Scientific Library - Scientificlib.com