''Euprymna morsei'', the Mimika bobtail squid, is a species of

Indo-Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...

bobtail squid Bobtail squid (order Sepiolida) are a group of cephalopods closely related to cuttlefish. Bobtail squid tend to have a rounder mantle than cuttlefish and have no cuttlebone. They have eight suckered arms and two tentacles and are generally qui ...

from the family

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

Description

''Euprymna morsei'' has a plump, dome-shaped mantle in which the dorsal mantle is fused to head. It has wide but short semicircular fins which are shorter than the mantle length either anteriorly or posteriorly. At their posterior ends the fins are widely separated while their anterior origin is behind the margin of the mantle. The suckers on the non-

hectocotylised A hectocotylus (plural: ''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 i ...

arms are arranged similarly in both sexes in four series. In the males there are around 10 enlarged suckers in the ventral rows of arms II to IV which run towards the tip from the third or fourth suckers counting from the head. The males have a hectocotylus in which the upper half of left dorsal arm is modified with enlarged pedicels to the suckers which are densely packed to form 2 double rows of columnar structures and the suckers are reduced, having very small, fleshy, narrow openings. The inner end of this arm has a single papilla which resembles a nipple. The marginal suckers on arm I are slightly larger than the medial suckers. The

tentacular club All cephalopods possess flexible limbs extending from their heads and surrounding their beaks. These appendages, which function as muscular hydrostats, have been variously termed arms, legs or tentacles. Description In the scientific li ...

suckers are cup-shaped or spherical. There is no internal

gladius ''Gladius'' () is a Latin word meaning "sword" (of any type), but in its narrow sense it refers to the sword of ancient Roman foot soldiers. Early ancient Roman swords were similar to those of the Greeks, called '' xiphe'' (plural; singular ''xi ...

. There are a pair of saddle-shaped

bioluminescent Bioluminescence is the production and emission of light by living organisms. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some Fungus, fungi, microorganisms including ...

organs present in the inside of the mantle cavity on the

ink sac An ink sac is an anatomical feature that is found in many cephalopod mollusks used to produce the defensive cephalopod ink. With the exception of nocturnal and very deep water cephalopods, all Coleoidea (squid, octopus and cuttlefish) which dwell ...

. The colour varies from an iridescent gold through to purple, with large black

chromatophores Chromatophores are cells that produce color, of which many types are Biological pigment, pigment-containing cells, or groups of cells, found in a wide range of animals including amphibians, fish, reptiles, crustaceans and cephalopods. Mammals and ...

. They grow up to 40mm in mantle length. This species is

sympatric In biology, two related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter one another. An initially interbreeding population that splits into two or more distinct species sh ...

with and very similar to ''

Euprymna berryi ''Euprymna berryi'', commonly called hummingbird bobtail squid or Berry's bobtail squid among various other vernacular names, is a species of mollusc cephalopod in the family Sepiolidae. Description The hummingbird bobtail squid is a small sized ...

'' and the females of ''E. morsei'' and ''E. berryi'' are indistinguishable from one another.

Distribution

''Euprymna morsei'' is found from southern Japan south along the coasts of Korea and China to Malaysia and as far south as

Java Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's List ...

, a distribution encompassing

East East or Orient is one of the four cardinal directions or points of the compass. It is the opposite direction from west and is the direction from which the Sun rises on the Earth. Etymology As in other languages, the word is formed from the fa ...

and

South China Sea The South China Sea is a marginal sea of the Western Pacific Ocean. It is bounded in the north by the shores of South China (hence the name), in the west by the Indochinese Peninsula, in the east by the islands of Taiwan and northwestern Phil ...

s, the

Yellow Sea The Yellow Sea is a marginal sea of the Western Pacific Ocean located between mainland China and the Korean Peninsula, and can be considered the northwestern part of the East China Sea. It is one of four seas named after common colour terms ...

Gulf of Thailand The Gulf of Thailand, also known as the Gulf of Siam, is a shallow inlet in the southwestern South China Sea, bounded between the southwestern shores of the Indochinese Peninsula and the northern half of the Malay Peninsula. It is around in l ...

and the Philippines. There have been possible records from the

Bay of Bengal The Bay of Bengal is the northeastern part of the Indian Ocean, bounded on the west and northwest by India, on the north by Bangladesh, and on the east by Myanmar and the Andaman and Nicobar Islands of India. Its southern limit is a line between ...

and the

Maldive Islands Maldives (, ; dv, ދިވެހިރާއްޖެ, translit=Dhivehi Raajje, ), officially the Republic of Maldives ( dv, ދިވެހިރާއްޖޭގެ ޖުމްހޫރިއްޔާ, translit=Dhivehi Raajjeyge Jumhooriyyaa, label=none, ), is an archipelag ...

, but the Bay of Bengal records, at least, were based on females and are, therefore, uncertain. However, there is taxonomic uncertainty about the definition of ''E. morsei'' and other authorities have stated that this is a temperate species which is only found in the colder seas around Japan. The

taxonomy Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...

of the genus ''

Euprymna ''Euprymna'' is a genus of bobtail squid comprising a number of species. Species *'' Euprymna albatrossae'' (Voss, 1962) *'' Euprymna berryi'' (Sasaki, 1929), double-ear bobtail *''Euprymna brenneri'' (Sanchez et al., 2019) *''Euprymna bursa'' * ...

'' remains to be resolved to define its species limits.

Biology

''Euprymna morsei'' is a shallow water species which spends the day buried in soft substrates and emerge at night to feed, using their bioluminescent organs to emit just enough light to disguise their silhouette from predators such as

lancet fish Lancetfishes are large oceanic predatory fishes in the genus ''Alepisaurus'' ("scaleless lizard") in the monogeneric family Alepisauridae. Lancetfishes grow up to in length. Very little is known about their biology, though they are widely di ...

(''

Alepisaurus ferox ''Alepisaurus ferox'', the long snouted lancetfish, longnose lancetfish, or cannibal fish, is a species of lancetfish found in the ocean depths down to 1,830 m (6,000 ft). This species grows to in total length and a weight of . It is ...

'').

Fisheries

''Euprymna morsei'' is fished for food on a very small, local scale and sometimes taken as bycatch by fisheries.

References

{{Taxonbar, from=Q3130372 Bobtail squid Cephalopods described in 1881