''Stephanolepis hispidus'', the planehead filefish, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of bony fish, a

ray-finned Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or hor ...

fish in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Monacanthidae.

Description

The planehead filefish grows to a maximum length of but is more typically about long. The colour is

cryptic Cryptic may refer to: In science: * Cryptic species complex, a group of species that are very difficult to distinguish from one another * Crypsis, the ability of animals to blend in to avoid observation * Cryptic era, earliest period of the Earth ...

, being a more or less mottled pale brown, olive or green on a light coloured background, sometimes with darker brown splotches and streaks. The fish is laterally compressed and deep bodied. The snout is elongated with a terminal mouth. The large yellow eye is set high on the head and above it is a prominent retractable spine. This is the anterior of the two spines associated with the long dorsal fin, which also has 29 to 35 soft rays. The anal fin has no spines and between 30 and 35 soft rays. The pectoral fins are small and the tail fin is large and fan-shaped, often with two darker coloured bands.''Stephanolepis hispidus'' (Linnaeus, 1766)
FishBase. Retrieved 2012-01-04.''Stephanolepis hispidus''
Marine Species Identification Portal. Retrieved 2012-01-04. Planehead filefish are

sexually dimorphic Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

. In mature males, the second soft ray of the dorsal fin becomes greatly elongated and the scales on either side of the caudal peduncle develop into a patch of bristles. The elongated ray reaches between 104 and 128 mm. Females do not develop secondary sexual characteristics. They tend to have greater body depth than males, but variation in this trait exists in both sexes and overlap in measurements are recorded.

Distribution and habitat

The planehead filefish is found in the Atlantic Ocean at depths of up to . Its range extends from

Nova Scotia Nova Scotia ( ; ; ) is one of the thirteen provinces and territories of Canada. It is one of the three Maritime provinces and one of the four Atlantic provinces. Nova Scotia is Latin for "New Scotland". Most of the population are native Eng ...

Uruguay Uruguay (; ), officially the Oriental Republic of Uruguay ( es, República Oriental del Uruguay), is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast; while bordering ...

in the west and from the

Canary Islands The Canary Islands (; es, Canarias, ), also known informally as the Canaries, are a Spanish autonomous community and archipelago in the Atlantic Ocean, in Macaronesia. At their closest point to the African mainland, they are west of Morocc ...

Angola , national_anthem = " Angola Avante"() , image_map = , map_caption = , capital = Luanda , religion = , religion_year = 2020 , religion_ref = , coordina ...

in the east. It is found near the seabed on reefs and over sandy and muddy sea floors. It is often found among ''

Sargassum ''Sargassum'' is a genus of brown (class Phaeophyceae) macroalgae (seaweed) in the order Fucales. Numerous species are distributed throughout the temperate and tropical oceans of the world, where they generally inhabit shallow water and coral re ...

'' seaweed.

Biology

In the Canary Islands the growth and ageing of the planehead filefish have been studied. Spawning takes place in the summer and the age of the fish is established by using the fast and slow growth rings found in the anterior dorsal fin spine. The species has a lifespan of about three years and reaches half its final length by the end of its first year.

Uses

The planehead filefish can be used for human consumption. In the Canary Islands it is caught in fish traps and at one time was considered to be a by-catch, incidental to the capture of other, more desirable fish. However, since the 1980s, it has become a target species in its own right and by 2000, there were concerns about overfishing.

References

External links

* {{Taxonbar, from=Q2803497 Monacanthidae Fish described in 1766 Fish of the Atlantic Ocean Fish of Africa Fish of North America Fish of South America Fish of West Africa Taxa named by Carl Linnaeus