''Doryteuthis plei'', also known as the slender inshore squid or arrow squid, is a medium-sized

squid A squid (: squid) is a mollusc with an elongated soft body, large eyes, eight cephalopod limb, arms, and two tentacles in the orders Myopsida, Oegopsida, and Bathyteuthida (though many other molluscs within the broader Neocoleoidea are also ...

belonging to the family Loliginidae. It occurs abundantly in coastal waters of the

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

, from

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

northward to

North Carolina North Carolina ( ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, South Carolina to the south, Georgia (U.S. stat ...

Description

As both common names imply, these squid have elongate, cylindrical bodies with a length to width ratio of 7:1. The arms are in contrast short and weak; the two

tentacle In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work main ...

s are somewhat less than the mantle length. The

rhombus In plane Euclidean geometry, a rhombus (: rhombi or rhombuses) is a quadrilateral whose four sides all have the same length. Another name is equilateral quadrilateral, since equilateral means that all of its sides are equal in length. The rhom ...

-shaped fins are large, up to about 50 percent of the mantle length. Running the ventral length of the mantle is a noticeable ridge. The squid are a reddish orange colour with a large complement of

chromatophore Chromatophores are cells that produce color, of which many types are pigment-containing cells, or groups of cells, found in a wide range of animals including amphibians, fish, reptiles, crustaceans and cephalopod A cephalopod is any member o ...

s. The suckers of the arms possess blunt teeth. On the meaty ends (''clubs'') of the tentacles, there are four rows of suckers; the inner two (''mesial'') rows are three times as large as the outer two (''marginal'') rows. The larger suckers have horny rings with up to 45 teeth. These squid reach a maximum mantle length of 33 centimetres in males and 22 centimetres in females.

Sexual dimorphism Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...

is apparent, with the left ventral arm in males modified into a hectocotylus; this is used to facilitate fertilization during mating. Males also have a number of purple stripes running lengthwise on the ventral side of the mantle; along with other visual cues produced by chromatophores, these stripes are used in elaborate courtship displays.

Ecology

Due to their abundance, slender inshore squid are important to both commercial and subsistence fisheries. During the annual summer mating season, the squid congregate in large numbers near shore. During the austral summer in waters off

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

, annual catches may reach 763 metric tonnes. While there may be safety in their numbers, the squid are an important prey item for large

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

such as

tuna A tuna (: tunas or tuna) is a saltwater fish that belongs to the tribe Thunnini, a subgrouping of the Scombridae ( mackerel) family. The Thunnini comprise 15 species across five genera, the sizes of which vary greatly, ranging from the bul ...

and

shark Sharks are a group of elasmobranch cartilaginous fish characterized by a ribless endoskeleton, dermal denticles, five to seven gill slits on each side, and pectoral fins that are not fused to the head. Modern sharks are classified within the ...

s and a number of

cetacean Cetacea (; , ) is an infraorder of aquatic mammals belonging to the order Artiodactyla that includes whales, dolphins and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively c ...

s: pygmy killer whales,

orca The orca (''Orcinus orca''), or killer whale, is a toothed whale and the largest member of the oceanic dolphin family. The only extant species in the genus '' Orcinus'', it is recognizable by its black-and-white-patterned body. A cosmopol ...

Atlantic spotted dolphin The Atlantic spotted dolphin (''Stenella frontalis'') is a dolphin found in warm temperate and tropical waters of the Atlantic Ocean. Older members of the species have a very distinctive spotted coloration all over their bodies. Taxonomy The Atl ...

s, rough-toothed dolphins, and

bottlenose dolphin The bottlenose dolphin is a toothed whale in the genus ''Tursiops''. They are common, cosmopolitan members of the family Delphinidae, the family of oceanic dolphins. Molecular studies show the genus contains three species: the common bot ...

s are all known predators of slender inshore squid. Other predators include South African and Antarctic fur seals. The squid prey upon several species of estuarine fish, including: killifish, mosquitofish and mollies. Small

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

s such as grass shrimp are also taken.

References

* Vecchione, M., E. Shea, S. Bussarawit, F. Anderson, D. Alexeyev, C.-C. Lu, T. Okutani, M. Roeleveld, C. Chotiyaputta, C. Roper, E. Jorgensen & N. Sukramongkol. (2005). ''Phuket Marine Biological Center Research Bulletin'' 66: 23–26.

External links

{{Taxonbar, from1=Q47464464, from2=Q3201277 Cephalopods described in 1823 Doryteuthis