Cyclothone braueri

Cyclothone braueri

The Garrick or Brauer’s Bristlemouth (Cyclothone braueri Jespersen & Tåning, 1926) is a very small abyssal fish belonging to the Gonostomatidae family.

Systematics –
From a systematic point of view it belongs to:
Eukaryota domain,
Kingdom Animalia,
Subkingdom Eumetazoa,
Bilateria branch,
Superphylum Deuterostomia,
Phylum Chordata,
Subphylum Vertebrata,
Infraphylum Gnathostomata,
Class Actinopterygii,
Order Stomiiformes,
Gonostomatidae family,
Genus Cyclothone,
C. braueri species.

Geographic Distribution and Habitat –
The Cyclothone braueri is a cosmopolitan fish, therefore it is found present in all the seas of the world; particularly abundant in the Mediterranean Sea and in Italian waters. In the Strait of Messina they also rise to the surface.
It is a pelagic species and its marine habitat is that of the depths where it lives between 200 meters deep, during the day, and up to at least 2300 meters deep, in waters very far from the coast.

Description –
The Cyclothone braueri is a very small fish as the males measure up to about 30 mm and the females can reach up to about 50 mm.
The body is elongated and compressed at the sides and is without scales, which gives it a certain transparency; the color is whitish and slightly opaline, with a black belly, so much so that the black peritoneal membrane can be seen in transparency.
The upper profile of the head is clearly concave.
It has photophores which are larger than those of the congeners and there are 4 of them from the ventral to the origin of the anal and 12-14 from the anal to the base of the caudal.
The eyes are very small while the mouth is large and is able to open almost up to 180°. In the premaxilla there are 7 sets of teeth and in the long set of the maxilla about 56 teeth. However, the teeth are all the same length.
The number of gill spines in the first gill arch is lower than in congeners.
The pectoral fin is inserted midway along the body and has 13-15 soft, initially tall rays. The anal one (with 18-20 rays) is opposite and similar to the dorsal one, but it is longer. The caudal is broad and forked. The pectorals are modest and set low. The ventral fins, also of modest size, insert back, close to the anal fin.
It has 31 vertebrae.

Biology –
The Cyclothone braueri is a small fish of which little is known about its biology and reproduction, also due to the depths where it lives. However the stages in metamorphosis and the adults go down towards the thousand meters while in the winter months the latter go up to 200 meters.

Ecological Role –
Cyclothone braueri is a species that feeds on zooplankton organisms, especially crustaceans.
In turn, it is a small fish that is preyed upon by numerous species of fish and cetaceans, playing a very important role in marine food chains.
It is sometimes caught with bottom trawls or purse seines. However, it has no nutritional value for humans.
According to the IUCN Red List, the species is classified as Least Concern (LC) due to its wide distribution and because there is no evidence of decline or specific threats.

Guido Bissanti

Sources
– Wikipedia, the free encyclopedia.
– GBIF, the Global Biodiversity Information Facility.
– Louisy P., 2016. Guide to the identification of marine fish of Europe and the Mediterranean. Il Castello Editore, Milan.
– Nikiforos G., 2008. Fauna of the Mediterranean. Giunti Editore, Florence.
Photo source:
– https://iiif.mcz.harvard.edu/iiif/3/8630/full/max/0/default.jpg
– https://animaldiversity.org/collections/contributors/Grzimek_fish/Stomiiformes/Cyclothone_braueri/