''Heteroteuthis dispar'', also known as the odd bobtail, is a small deep water squid found in the North
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 ...
and the
Mediterranean Sea
The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern Eur ...
.
Taxonomy
''Heteroteuthis dispar'' is a deep sea species of squid and relatively little is known about it because of the difficulty of observing it ''in situ''. Its description is very similar to that of ''
Heteroteuthis hawaiiensis
''Heteroteuthis hawaiiensis'' is a species of bobtail squid native to the central and western Pacific Ocean. It occurs in waters off Hawaii, Bonin, the Ryukyu Islands, Indonesia, and the Great Australian Bight. ''H. hawaiiensis'' may also be pre ...
'', which is found in the central North
Pacific Ocean
The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...
. It has not been possible to compare the two species side by side and so it is unclear whether they are identical.
DNA sequencing
DNA sequencing is the process of determining the nucleic acid sequence – the order of nucleotides in DNA. It includes any method or technology that is used to determine the order of the four bases: adenine, thymine, cytosine, and guanine. The ...
should eventually clarify this issue.
Distribution
''Heteroteuthis dispar'' is found in the Mediterranean Sea and across the Atlantic Ocean. The range includes a broad swathe from southwest
Ireland
Ireland (, ; ; Ulster Scots dialect, Ulster-Scots: ) is an island in the North Atlantic Ocean, in Northwestern Europe. Geopolitically, the island is divided between the Republic of Ireland (officially Names of the Irish state, named Irelan ...
south to the coastal fringes of
West Africa
West Africa, also known as Western Africa, is the westernmost region of Africa. The United Nations geoscheme for Africa#Western Africa, United Nations defines Western Africa as the 16 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Gha ...
, across to
Bermuda
Bermuda is a British Overseas Territories, British Overseas Territory in the Atlantic Ocean, North Atlantic Ocean. The closest land outside the territory is in the American state of North Carolina, about to the west-northwest.
Bermuda is an ...
, the
Caribbean Sea
The Caribbean Sea is a sea of the Atlantic Ocean, North Atlantic Ocean in the tropics of the Western Hemisphere, located south of the Gulf of Mexico and southwest of the Sargasso Sea. It is bounded by the Greater Antilles to the north from Cuba ...
and the eastern fringes of the United States north to
Maryland
Maryland ( ) is a U.S. state, state in the Mid-Atlantic (United States), Mid-Atlantic region of the United States. It borders the states of Virginia to its south, West Virginia to its west, Pennsylvania to its north, and Delaware to its east ...
There are five pairs of appendages. Arms 1 and 2 are fused at the base and each is a
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 ...
in the male. Arm 3 has two or three greatly enlarged suckers at the
proximal
Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...
end and a few moderate sized ones at the
distal
Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position provi ...
end. Arms 3 and 4 are longer than the others. In the female, arms 1 and 2 have no suckers on the distal ends. The tentacles are retractable, slender and whip-like, with a short club with eight rows of microscopically small suckers.Marine species /ref>
The funnel is found under the head and the locking apparatus has a deep, curved groove and an angled posterior pit. The mantle margin is detached from the head, and the neck cartilage is either free or fused. On the underside, the mantle shield is confined to the anterior part of the mantle. The fins are quite short and are attached to the posterior part of the mantle from which they bulge forwards. The mantle length in the adult female is about 25 millimetres.
Biology
The male ''Heteroteuthis dispar'' produces a
spermatophore
A spermatophore, from Ancient Greek σπέρμα (''spérma''), meaning "seed", and -φόρος (''-phóros''), meaning "bearing", or sperm ampulla is a capsule or mass containing spermatozoa created by males of various animal species, especiall ...
or sperm package which is transferred to the female before she is sexually mature. She stores it and makes use of it at the optimal time for fertilisation. The spermatophore is large, constituting about 3% of her weight, and therefore disadvantageous to her. This reproductive practice may be due to the fact that finding a mate deep in the ocean at the appropriate time is difficult.
This species is found in the
mesopelagic zone
The mesopelagic zone (Greek μέσον, middle), also known as the middle pelagic or twilight zone, is the part of the pelagic zone that lies between the photic epipelagic and the aphotic bathypelagic zones. It is defined by light, and begins ...
of the ocean at depths down to 1600 metres. Spawning takes place on the bottom and the
paralarva
Coleoidea
or Dibranchiata is one of the two subclasses of cephalopod molluscs containing all the various taxa popularly thought of as "soft-bodied" or "shell-less" (i.e. octopus, squid and cuttlefish). Unlike its extant sister group Nautiloidea ...
e live at even greater depths, down to 3000 metres. Adults often live in groups at depths of 200 to 300 metres, often in areas where
shrimp
A shrimp (: shrimp (American English, US) or shrimps (British English, UK)) is a crustacean with an elongated body and a primarily Aquatic locomotion, swimming mode of locomotion – typically Decapods belonging to the Caridea or Dendrobranchi ...
s are found.
Predators
Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill ...
that feed on this squid include
dolphin
A dolphin is an aquatic mammal in the cetacean clade Odontoceti (toothed whale). Dolphins belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontopori ...
s (''
Grampus griseus
Risso's dolphin (''Grampus griseus'') is a marine mammal and dolphin, the only species of the genus ''Grampus''. Some of the most closely related species to these dolphins include: pilot whales (''Globicephala'' spp.), pygmy killer whales (''Fere ...
''), the
velvet belly lantern shark
The velvet belly lanternshark (or simply velvet belly) (''Etmopterus spinax'') is a species of dogfish shark in the family Etmopteridae. One of the most common deepwater sharks in the northeastern Atlantic Ocean, the velvet belly is found from Ic ...
(''Etmopterus spinax''), the
blackmouth catshark
The blackmouth catshark (''Galeus melastomus'') is a species of deepwater catshark, belonging to the family (biology), family Pentanchidae, common in the northeastern Atlantic Ocean from Iceland to Senegal, including the Mediterranean Sea. It is ...
(''Galeus melastomus''), the
small-spotted catshark
The small-spotted catshark (''Scyliorhinus canicula''), also known as the sandy dogfish, lesser-spotted dogfish, rough-hound or morgay (in Scotland and Cornwall), is a catshark of the family Scyliorhinidae. It is found on the continental shelves ...
, (''Scyliorhinus canicula''), the
swordfish
The swordfish (''Xiphias gladius''), also known as the broadbill in some countries, are large, highly migratory predatory fish characterized by a long, flat, pointed bill. They are the sole member of the Family (biology), family Xiphiidae. They ...
(''Xiphias gladius'') and
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 ...
(''
Thunnus alalunga
The albacore (''Thunnus alalunga''), known also as the longfin tuna, is a species of tuna of the order Scombriformes. It is found in temperate and tropical waters across the globe in the epipelagic and mesopelagic zones. There are six distinct s ...
'').
''Heteroteuthis dispar'' can be
bioluminescent
Bioluminescence is the emission of light during a chemiluminescence reaction by living organisms. Bioluminescence occurs in multifarious organisms ranging from marine vertebrates and invertebrates, as well as in some fungi, microorganisms inc ...
, emitting light from
photophore
A photophore is a specialized anatomical structure found in a variety of organisms that emits light through the process of boluminescence. This light may be produced endogenously by the organism itself (symbiotic) or generated through a mut ...
s containing bacterial
symbionts
Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term
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 ...
. This can be released into the water through the funnel and the glowing cloud is believed to blind or confuse predators for long enough for the squid to make its escape.Young, R.E. 1977. Ventral bioluminescent countershading in midwater cephalopods. Symposium of the Zoological Society of London 38: 161-190.