Sharpear Enope Squid
Encyclopedia
The Sharpear Enope Squid (Ancistrocheirus lesueurii) is the only species in the genus Ancistrocheirus and family Ancistrocheiridae. With a mantle length of 25 cm, this moderately sized squid
may be found throughout the tropical and subtropical oceans. They tend to be found at mesopelagic
depths (200-1000 metres down).
Although only one species is recognized, some have suggested that more than one species may exist due to differences in the paralarval
morphology
. Paralarva is the first free-living stage for cephalopod
s.
s. There are hooks on all its arm
s. The suckers are absent from its manus and the squid's dactylus
is reduced.
s throughout its body. Large photophores are present on its head, funnel, base of arms, and tentacular stalk. Other photophores are present on the ventral surface of its mantle
(usually 22), and there are numerous very small photophores on its head, funnel, base of arms II and tentacular stalk. Mature males will have large photophores on tips of arms IV opposite the mouth. Mature females have photophores on tips of its dorsal
six arms. The number of large photopores on the Sharpear Enope Squid's mantle increases as it matures.
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...
may be found throughout the tropical and subtropical oceans. They tend to be found at mesopelagic
Mesopelagic
The mesopelagic is that part of the pelagic zone that extends from a depth of 200 to 1000 metres below the ocean surface. It lies between the photic epipelagic above and the aphotic bathypelagic below, where there is no light at all...
depths (200-1000 metres down).
Although only one species is recognized, some have suggested that more than one species may exist due to differences in the paralarval
Paralarva
Paralarvae is the term used to describe the young planktonic stages of cephalopods, between hatchling and subadult. It is used to differentiate it from the term 'larva' used in animals which undergo true metamorphosis. They have been observed only on members of the orders Octopoda and Teuthida.The...
morphology
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
. Paralarva is the first free-living stage for cephalopod
Cephalopod
A cephalopod is any member of the molluscan class Cephalopoda . These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot...
s.
Characteristics
The buccal crown of the Sharpear Enope Squid is heavily pigmented. The squid has no vesicleVesicle (biology)
A vesicle is a bubble of liquid within another liquid, a supramolecular assembly made up of many different molecules. More technically, a vesicle is a small membrane-enclosed sack that can store or transport substances. Vesicles can form naturally because of the properties of lipid membranes , or...
s. There are hooks on all its arm
Cephalopod arm
A cephalopod arm is distinct from a tentacle, though the terms are often used interchangeably.Generally, cephalopod arms have suckers along most of their length, as opposed to tentacles, which have suckers only near their ends. Octopuses have eight arms and no tentacles, while squid and cuttlefish...
s. The suckers are absent from its manus and the squid's dactylus
Dactylus
The dactylus is the tip region of the tentacular club of cephalopods and of the leg of some crustaceans . In cephalopods, the dactylus is narrow and often characterized by the asymmetrical placement of suckers and the absence of a dorsal protective membrane...
is reduced.
Photophores
There are photophorePhotophore
A photophore is a light-emitting organ which appears as luminous spots on various marine animals, including fish and cephalopods. The organ can be simple, or as complex as the human eye; equipped with lenses, shutters, color filters and reflectors...
s throughout its body. Large photophores are present on its head, funnel, base of arms, and tentacular stalk. Other photophores are present on the ventral surface of its mantle
Mantle (mollusc)
The mantle is a significant part of the anatomy of molluscs: it is the dorsal body wall which covers the visceral mass and usually protrudes in the form of flaps well beyond the visceral mass itself.In many, but by no means all, species of molluscs, the epidermis of the mantle secretes...
(usually 22), and there are numerous very small photophores on its head, funnel, base of arms II and tentacular stalk. Mature males will have large photophores on tips of arms IV opposite the mouth. Mature females have photophores on tips of its dorsal
Dorsum (biology)
In anatomy, the dorsum is the upper side of animals that typically run, fly, or swim in a horizontal position, and the back side of animals that walk upright. In vertebrates the dorsum contains the backbone. The term dorsal refers to anatomical structures that are either situated toward or grow...
six arms. The number of large photopores on the Sharpear Enope Squid's mantle increases as it matures.