''Teuthidodrilus samae'', dubbed as the squidworm, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of acrocirrid marine

annelid The annelids (), also known as the segmented worms, are animals that comprise the phylum Annelida (; ). The phylum contains over 22,000 extant species, including ragworms, earthworms, and leeches. The species exist in and have adapted to vario ...

worms. It is

free-swimming Motility is the ability of an organism to move independently using metabolic energy. This biological concept encompasses movement at various levels, from whole organisms to cells and subcellular components. Motility is observed in animals, mi ...

and can be found in the deep sea

water column The (oceanic) water column is a concept used in oceanography to describe the physical (temperature, salinity, light penetration) and chemical ( pH, dissolved oxygen, nutrient salts) characteristics of seawater at different depths for a defined ...

at depths of . It feeds on

marine snow In the deep ocean, marine snow (also known as "ocean dandruff") is a continuous shower of mostly organic detritus falling from the upper layers of the water column. It is a significant means of exporting energy from the light-rich photic zone to ...

and can grow to about in length and in width. It is named for the ten squid-like appendages emerging from its head. It was discovered in 2007 in the

benthopelagic zone 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 of ...

of the

Celebes Sea The Celebes Sea ( ; ) or Sulawesi Sea (; ) of the western Pacific Ocean is bordered on the north by the Sulu Archipelago and Sulu Sea and Mindanao Island of the Philippines, on the east by the Sangihe Islands chain, on the south by Sulawes ...

, near the

Tawi-Tawi Tawi-Tawi, officially the Province of Tawi-Tawi ( Tausug: ''Wilaya' sin Tawi-Tawi''; Sinama: ''Jawi Jawi/Jauih Jauih''; ), is an island province in the Philippines located in the Bangsamoro Autonomous Region in Muslim Mindanao (BARMM). The capit ...

islands of the

Philippines The Philippines, officially the Republic of the Philippines, is an Archipelagic state, archipelagic country in Southeast Asia. Located in the western Pacific Ocean, it consists of List of islands of the Philippines, 7,641 islands, with a tot ...

. It is the only species in the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

''Teuthidodrilus''.

Discovery

''Teuthidodrilus samae'' was discovered in the 2007 "Exploring the Inner Space of the Celebes Sea" expedition by the

remotely operated underwater vehicle A remotely operated underwater vehicle (ROUV) or remotely operated vehicle (ROV) is a free-swimming submersible craft used to perform underwater observation, inspection and physical tasks such as valve operations, hydraulic functions and other g ...

Global Explorer ROV Global Explorer ROV is a unique deep water remotely operated vehicle that has made numerous dives below on science and survey expeditions for National Geographic, the National Oceanographic and Atmospheric Administration (NOAA) and other resear ...

'' operated from the Philippine research vessel BRP ''Hydrographer Presbitero''. Seven specimens were observed and collected from the deep-water column of the

seafloor The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean. All floors of the ocean are known as seabeds. The structure of the seabed of the global ocean is governed by plate tectonics. Most of ...

) of the

near the

islands of the

. This area is part of the

Coral Triangle The Coral Triangle (CT) is a roughly triangular area in the tropical waters around Indonesia, Malaysia, Papua New Guinea, the Philippines, Solomon Islands, and Timor-Leste. This area contains at least 500 species of reef-building corals in each ...

, a location known for its increased biodiversity. The specimens were recovered at depths ranging from , all within the

demersal zone 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 ...

of around from the

Taxonomy

''Teuthidodrilus samae'' is the only species classified in the

''Teuthidodrilus.'' It belongs to the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Acrocirridae Acrocirridae is a family of polychaete worms. Acrocirrids are detritivores (deposit feeders), catching falling particles with numerous long prostomial tentacles. There are eight known genera, and at least 21 described species and subspecies wi ...

of the

class Class, Classes, or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used d ...

Polychaeta in the

phylum In biology, a phylum (; : phyla) is a level of classification, or taxonomic rank, that is below Kingdom (biology), kingdom and above Class (biology), class. Traditionally, in botany the term division (taxonomy), division has been used instead ...

Annelida The annelids (), also known as the segmented worms, are animals that comprise the phylum Annelida (; ). The phylum contains over 22,000 extant species, including ragworms, earthworms, and leeches. The species exist in and have adapted to variou ...

. It is classified along with the genus ''

Swima ''Swima'' is a genus of marine polychaete Annelid, worms found in the ocean at depths between . Even if they are agile swimmers, they are often seen hanging immobile in the water column as they are neutrally buoyant. This Bathyal zone, deep ocean ...

'' in the "swimming

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

" within the family Acrocirridae. A similar undescribed and uncollected specimen observed from off western

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

by the ''Hercules 7'' ROV in 2004 may represent a second species in the genus. The generic name comes from

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

for "squid worm", while the

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

is in honor of the

Sama people The Sama-Bajau include several Austronesian ethnic groups of Maritime Southeast Asia. The name collectively refers to related people who usually call themselves the Sama or Samah (formally A'a Sama, "Sama people"); or are known by the exonym ...

of the Tawi-Tawi islands. The

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

is deposited in the

National Museum of the Philippines The National Museum of the Philippines () is an umbrella government organization that oversees a number of national museums in the Philippines, including Ethnography, ethnographic, Anthropology, anthropological, Archaeology, archaeological, an ...

Physical characteristics

The collected specimens ranged in size from in body length. The

has a body width of around . Adults are light brown when alive, becoming light black in color when preserved. Juveniles are almost transparent. The body is divided into 25 segments ( chaetigers) with pairs of large flattened paddle-shaped

notopodia In invertebrates, the term parapodium (Greek language, Gr. ''para'', beyond or beside + ''podia'', feet; : parapodia) refers to lateral outgrowths or protrusions from the body. Parapodia are predominantly found in Annelid, annelids, where they ar ...

, around in length. Each notopodium has greater than 50

chaeta A chaeta or cheta (; ) is a chitinous bristle or seta found on annelid worms, although the term is also frequently used to describe similar structures in other invertebrates such as arthropods. Polychaete annelids (''polychaeta'' literally me ...

e (bristles) arranged into a fin-like shape, except the first segment which has less than 10. Alongside the notopodia are pairs of

neuropodia In invertebrates, the term parapodium ( Gr. ''para'', beyond or beside + ''podia'', feet; : parapodia) refers to lateral outgrowths or protrusions from the body. Parapodia are predominantly found in annelids, where they are paired, unjointed late ...

, each with around 2 to 4 chaetae. The head segment (

prostomium The prostomium (From Ancient Greek, meaning "before the mouth"; : prostomia; sometimes also called the "acron") is the Cephalization, cephalized first body segment in an annelid worm's body at the anterior end. It is in front of (but does not in ...

) supports five pairs of long appendages. Four pairs of appendages are sensory and breathing organs (branchiae) at least in length. They are arranged along the upper and side ridges of the head, arising from the pair of feather-like

nuchal organ The nuchal organ is a ciliated pit or groove present at the posterior end of the prostomium of annelid worms, some cephalopods, and other invertebrates. Annelids only possess one nuchal organ, although the nature of the grooving may make it appea ...

s which analyze chemical signals in the sea. The fifth pair of appendages are grooved and coiled feeding

palp Pedipalps (commonly shortened to palps or palpi) are the secondary pair of forward appendages among chelicerates – a group of arthropods including spiders, scorpions, horseshoe crabs, and sea spiders. The pedipalps are lateral to the chelicera ...

s arising from below the mouth, which is located in the front-bottom corner of the head. Their internal anatomy is relatively visible from the outside since their outer body is semi-transparent. Two parallel

ventral nerve cord The ventral nerve cord is a major structure of the invertebrate central nervous system. It is the functional equivalent of the vertebrate spinal cord. The ventral nerve cord coordinates neural signaling from the brain to the body and vice ve ...

s run lengthwise throughout the body, fusing into two pairs of

ganglia A ganglion (: ganglia) is a group of neuron cell bodies in the peripheral nervous system. In the somatic nervous system, this includes dorsal root ganglia and trigeminal ganglia among a few others. In the autonomic nervous system, there a ...

in each segment. The gut forms three loops in the second to sixth segments. The circulatory system consists of a heart body and large vessels leading to the gills. The pair of

nephridia The nephridium (: nephridia) is an invertebrate organ, found in pairs and performing a function similar to the vertebrate kidneys (which originated from the chordate nephridia). Nephridia remove metabolic wastes from an animal's body. Nephridia co ...

extends from the first segment to the fifth segment. The female

gonad A gonad, sex gland, or reproductive gland is a Heterocrine gland, mixed gland and sex organ that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. The male gon ...

s are located in the second to fourth segments with beige-colored grape-like clusters of variously-sized

ova , abbreviated as OVA and sometimes as OAV (original animation video), are Japanese animated films and special episodes of a series made specially for release in home video formats without prior showings on television or in theaters, though the ...

(with a maximum diameter of ).

Behavioral characteristics

Not much is known of this creature’s behavior other than its ability to swim with proficiency using their paddle-like notopodia. It is categorized as a suspension feeder since it consumes

, which consists of pieces from animals, plants, feces and other organic materials that precipitate from the higher parts of the ocean towards the abyss. In total, sixteen specimens were observed and seven were collected within just a few dives suggesting that this animal is a common member of the benthopelagic community of the Celebes Sea basin.

References

External links

* {{Taxonbar, from1=Q15303032, from2=Q1948429 Terebellida Taxa described in 2010 Polychaete genera