''Sepia braggi'', the slender cuttlefish, is a species of
cuttlefish
Cuttlefish, or cuttles, are Marine (ocean), marine Mollusca, molluscs of the order (biology), suborder Sepiina. They belong to the class (biology), class Cephalopoda which also includes squid, octopuses, and nautiluses. Cuttlefish have a unique ...
native to the Indo-Pacific Ocean. It has been found in coastal waters of southern Australia.
This species was first collected in South Australia by its namesake,
William Lawrence Bragg
Sir William Lawrence Bragg (31 March 1890 – 1 July 1971) was an Australian-born British physicist who shared the 1915 Nobel Prize in Physics with his father William Henry Bragg "for their services in the analysis of crystal structure by ...
. ''Sepia braggi'' was then described by
Sir Joseph Cooke Verco in 1907.''Sepia braggi'' is part of the subgenus ''
Doratosepion'' which contains to 41 species of cuttlefish in total.
Description
''Sepia braggi'' is a relatively small species of cuttlefish. Females of the species are larger than males and they grow to a
mantle length of 80 mm and 49 mm, respectively. The
mantle elongates to 3 times longer than it is wide. The mantle is cigar-shaped and triangular towards the anterior end.
Narrow fins extend along the lateral margin of the mantle and widen along the posterior. The head is short and narrower than the mantle.
The
cuttlebone
Cuttlebone, also known as cuttlefish bone, is a hard, brittle internal structure (an internal Mollusc shell, shell) found in all members of the family (biology), family Sepiidae, commonly known as cuttlefish, within the cephalopods. In othe ...
tends to have a similar length to the mantle. The common name of ''S. braggi'' originates from its slender cuttlebone, which is lanceolate in shape.
The
tentacular club
All cephalopods possess flexible limbs extending from their heads and surrounding their cephalopod beak, beaks. These appendages, which function as muscular hydrostats, have been variously termed arms, legs or tentacles.
Description
In ...
is relatively short, with five rows of
suckers.
The suckers are all approximately the same size except for 5 or 6 suckers in the middle row which are 2 to 3 times larger. The suckers on the arms are dispersed and minute in size.
The arms of the males are large compared to the females, with 35.2 mm to 57.8 mm in length, while the arms of the female range from 30.6 mm to 39.6 mm in length.
In contrast to similar species, the
hectocotylus
A hectocotylus (: hectocotyli) is one of the arms of male cephalopods that is specialized to store and transfer spermatophores to the female. Structurally, hectocotyli are muscular hydrostats. Depending on the species, the male may use it merel ...
is absent.
This cuttlefish can also be identified by its beak, which is useful for examining the stomachs of fish. Of the ''
Sepia genus, S. braggi'' is only species that does not have a darkened lateral band on the upper and lower beak. Also, on the upper beak, the fully darkened section is much smaller (2.6 mm) than other species of ''Sepia.''
The head and mantle of ''Sepia braggi'' are a buff, pinkish brown in color.
The fins tend to be pale brown and the ridges along the mantle are orange-pink. What separates ''Sepia braggi'' from all other species of cuttlefish are the short purple bars and blotches on the arms.
This pigmentation is very distinctive and clearly visible, even on smaller or juvenile specimens.
Distribution
''Sepia braggi'' are located in Southern Australia, from southern
New South Wales
New South Wales (commonly abbreviated as NSW) is a States and territories of Australia, state on the Eastern states of Australia, east coast of :Australia. It borders Queensland to the north, Victoria (state), Victoria to the south, and South ...
to
Western Australia
Western Australia (WA) is the westernmost state of Australia. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to the south, the Northern Territory to the north-east, and South Australia to the south-east. Western Aust ...
. It is a
demersal
The demersal zone is the part of the sea or ocean (or deep lake) consisting of the part of the water column near to (and significantly affected by) the seabed and the benthos. The demersal zone is just above the benthic zone and forms a layer o ...
species, typically found in depth between 30 and 86 meters. One source does give a maximum depth for S. braggi of 176 m,
though it is possible that those from greater depths may have been misidentified and perhaps refer to the species of
S. limata,
S. rhoda or
S. vercoi.
The Dorarosepion species from the from southern and eastern Australia are largely
allopatric
Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from ...
, though there is some overlap in the distribution of S. braggi and
S. cottoni off south-western Australia. ''Sepia braggi'' is one of three species of cuttlefish known to inhabit
Spencer Gulf
The Spencer Gulf is the westernmost and larger of two large inlets (the other being Gulf St Vincent) on the southern coast of Australia, in the state of South Australia, facing the Great Australian Bight. It spans from the Cape Catastrophe an ...
in South Australia.
Specimens are rarely caught there by
prawn trawlers.
Diet and ecology
Similar to other cuttlefish species, ''S. braggi'' feeds on small crabs, other crustaceans and fish.
Sharks, large fish and seals are known predators of cuttlefish.
''
Sepia apama
The giant cuttlefish (''Ascarosepion apama''), also known as the Australian giant cuttlefish, is the world's largest cuttlefish species, growing to in mantle (mollusc), mantle length and up to in total length (total length meaning the whole ...
'' and ''
Sepia novaehollandiae'' are the main competitors of the ''Sepia braggi'' as both species are larger and more common.
Fisheries
''Sepia braggi'' are rarely encountered and are relatively small. Therefore, the species is classified by fisheries as low value and ''S. braggi'' is only caught as
by-catch
Bycatch (or by-catch), in the fishing industry, is a fish or other marine species that is caught unintentionally while fishing for specific species or sizes of wildlife. Bycatch is either the wrong species, the wrong sex, or is undersized or juve ...
.
References
{{Taxonbar, from=Q2562486
Sepia
Cephalopods described in 1907