Greater weever

The term "weever" is thought to originate from the Anglo-Saxon word "wivre", which translates to "viper". == Description ==

The greater weever is an elongated and laterally flattened fish with a distinct superior mouth that is inclined upwards. The lower jaw is longer than the upper jaw. The head is compact flat and relatively big and the eyes sit almost on top of it.⁠ The upper rim of the eye has two to three small spines, in front of each eye. The five to seven spiny fin rays on its first dorsal fin and the thorns on each of the gill covers have venom glands at their basis. Additionally, oblique black stripes can be found laterally (this pattern is described as tiger-like by Müller). While the largest female recorded in the Eastern Black Sea was long, the findings in other studies suggest, that Trachinus draco has a much bigger range in size than that found in this study. In the Algarve Coast of Southern Portugal, the largest female found by Santos et al. had a total maximum length of . But also in the Black Sea specimens have been observed, that outrange the largest female found by Ak & Genç in 2013. The largest female found by Ak et al. in the Black Sea had a total maximum length of . == Ecology and behaviour ==

Depth The greater weever has been shown to occur in depths ranging from shallow water up to , where it inhabits mostly muddy or sandy grounds. There it lurks until potential prey approaches, which it then attacks in a swift and sudden manner. At night, the greater weever is believed to swim around freely, even pelagically. This is supported by the finding that prey caught during daytime is already mostly digested by the night of the same day.⁠⁠⁠ The frequency of empty stomachs, in the specimens found in the eastern Adriatic Sea was around 15% in general, but differed significantly through the year. In winter the frequency of empty stomachs was highest, with a maximum at around 43.3% and was lowest in summer with 6.8% and in autumn with 7.8%. The eggs may have a need for relatively warm water with a relatively low salinity to hatch in greater numbers.⁠ == Toxicity ==

Venomous apparatus The venomous apparatus of T. draco consists of one spine on each operculum and five to eight dorsal spines. The spines on the operculum point towards the cauda, or tail, and are slightly bent downwards. The opercular spines arise from the upper edge of the operculum and are connected to the operculum with one third of their complete length. The other two thirds of their length lies free along the operculum. The total length of the opercular spines is approximately 27 mm. The spine itself is "covered by an integumentary sheath". Toxin The potentially lethal protein component in the crude venom of T. draco is a 105 kDa polypeptide which is called Dracotoxin. The crude venom of T. draco has been shown to have membrane depolarizing and haemolytic characteristics. Those characteristics could be retraced to said single protein component. The depolarisation effect however could not be explained by well-established approaches. Neither does the depolarisation effect take place through Na+ or K+-channels nor through Na+-K+-ATPase activity.⁠ The weever sting is often followed by first ischemic and subsequently hyperemic effects in the tissue surrounding the sting. These effects might be related to the high concentrations of histamines and catecholamines found in the venom.⁠ ⁠⁠While Church & Hodgson (2002) suggest a cholinesterase activity of the toxin itself, Haavaldsen & Fonnum (1963) interpreted their finding of a high concentration of cholinesterase in the venom as a sign for a cholinergic mechanism in the production of the venom because cholinesterase activity hasn't yet been described in the venoms of the animal kingdom. As Russel & Emery (1960) stated, the toxin extract of T. draco has a greyish colour but is clear in its appearance. It is said to have a "fishy taste" and "ammoniacal odor". The pH value of the extract seems to be 6.78 and is with that slightly sour. The pain can in some cases reach up to a 10/10 on the numeric rating scale. In a reported case from 1782, a fisherman who had been stung, amputated his own finger to relieve the pain.⁠⁠ Even if there are reported cases of fatal accidents with T. draco, it is widely believed that those are due to secondary infections and sepsis rather than to the toxin itself.⁠ Treatment There are as many recommended treatments for a sting of the greater weever as there are fishermen who were stung by them. These recommendations reach from the application of hot water or vinegar to more arcane methods like fish liver, tobacco juice or the suggestion of "burning the devilish weever, swear and pray".⁠ The modern medicine does in fact recommend the application of any kind of heat preferably to souse the affected limb into hot water (40–42 °C). Beside this first aid attempt to ease the pain it is recommended to clean the wound and to see a physician because antibiotics, further analgesics or even a tetanus prophylaxis might be appropriate.⁠ == Relationship with humans ==

The greater weever is sold commercially in France, where it is seen as a delicacy, and is often caught as by-catch.⁠ It is also commercially available in ⁠Spain, where it is often mixed with other by-catch fish (such as gurnards and the annular seabream) and sold collectively under the name of "morralla".⁠ == References ==