The jellynose fishes or tadpole fishes are the small order Ateleopodiformes. This group of

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or hor ...

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

, containing a single family Ateleopodidae. It has about a dozen

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

in four

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

, but these enigmatic fishes are in need of

taxonomic 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. ...

revision. The

scientific name In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

means "''Ateleopus''-shaped", from ''

Ateleopus ''Ateleopus'' is a genus of ray-finned fish in the jellynose family Ateleopodidae. It is the type genus of its family, and the order Ateleopodiformes. For some time, it was known as ''Podateles'', because ''Ateleopus'' had been used to repla ...

'' (the

type genus In biological taxonomy, the type genus is the genus which defines a biological family and the root of the family name. Zoological nomenclature According to the International Code of Zoological Nomenclature, "The name-bearing type of a nominal f ...

) + the standard

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

order

suffix In linguistics, a suffix is an affix which is placed after the stem of a word. Common examples are case endings, which indicate the grammatical case of nouns, adjectives, and verb endings, which form the conjugation of verbs. Suffixes can carry ...

"-formes". It ultimately derives from

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...

''atelēs'' (ἀτελής, "imperfect") + ''pous'' (πούς, "foot") +

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

''forma'' ("external form"), the Greek part in reference to the reduced

pectoral Pectoral may refer to: * The chest region and anything relating to it. * Pectoral cross, a cross worn on the chest * a decorative, usually jeweled version of a gorget * Pectoral (Ancient Egypt), a type of jewelry worn in ancient Egypt * Pectorali ...

and

ventral fin Pelvic fins or ventral fins are paired fins located on the ventral surface of fish. The paired pelvic fins are homologous to the hindlimbs of tetrapods. Structure and function Structure In actinopterygians, the pelvic fin consists of two en ...

s of the jellynoses.

Description and ecology

Jellynoses are deep-water, bottom-dwelling,

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...

fishes. They are known from the

Caribbean Sea The Caribbean Sea ( es, Mar Caribe; french: Mer des Caraïbes; ht, Lanmè Karayib; jam, Kiaribiyan Sii; nl, Caraïbische Zee; pap, Laman Karibe) is a sea of the Atlantic Ocean in the tropics of the Western Hemisphere. It is bounded by Mexico ...

, eastern

Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe an ...

, the western and central

Indopacific 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 ...

, and the Pacific coast of

Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...

.Olney (1998), Nelson (2006): p.213 Their skeletons are largely

cartilage Cartilage is a resilient and smooth type of connective tissue. In tetrapods, it covers and protects the ends of long bones at the joints as articular cartilage, and is a structural component of many body parts including the rib cage, the neck an ...

(hence "jellynose"), although they are true

teleost Teleostei (; Greek ''teleios'' "complete" + ''osteon'' "bone"), members of which are known as teleosts ), is, by far, the largest infraclass in the class Actinopterygii, the ray-finned fishes, containing 96% of all extant species of fish. Tel ...

s and not closely related to

Chondrichthyes Chondrichthyes (; ) is a class that contains the cartilaginous fishes that have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or ''bony fishes'', which have skeletons primarily composed of bone tissue. ...

. The heads are large, with a bulbous nose, and the (usually) elongated body tapers towards the tail. Their

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

s are very small, and except for ''Guentherus'', it is merged with the long

anal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

(which has 70

fin ray Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as see ...

s or more). The

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral surface of fish. The paired pelvic fins are homologous to the hindlimbs of tetrapods. Structure and function Structure In actinopterygians, the pelvic fin consists of two en ...

s of juveniles have up to 10 rays, but in adults this is reduced to a single elongated ray at the throat. Again, ''Guentherus'' is an exception, retaining several fins as adults and having

s that are located behind (not below) the pectoral fins.

Dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through conv ...

s tend to be high, with a rather short base (9-13 rays, but in some as few as three); they are placed just behind the head. They have seven branchiostegal rays. The species have a range of sizes, the longest reaching . Most of the species are poorly known, but the highfin tadpole fish (''Guentherus altivelis'') is of potential interest for

commercial fishing Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must often ...

Systematics

Together with their relatives, the

Stomiiformes Stomiiformes is an order of deep-sea ray-finned fishes of very diverse morphology. It includes, for example, dragonfishes, lightfishes (Gonostomatidae and Phosichthyidae), loosejaws, marine hatchetfishes and viperfishes. The order contains 4 ...

, the jellynoses are often placed in the

superorder Order ( la, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and ...

Stenopterygii Stenopterygii are a superorder of ray-finned fish in the infraclass Teleostei. Their validity is somewhat doubtful, as the group was established to separate, out of a large group of closely related Teleostei, a mere two rather peculiarly autapom ...

. Whether it is indeed justified to accept such a small group is doubtful; it may well be that the closest living relatives of the "Stenopterygii" are found among the superorder Protacanthopterygii, and that the former would need to be merged in the latter. In some classifications, the "Stenopterygii" are kept separate but included with the Protacanthopterygii and the

superorder Cyclosquamata in an unranked

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

called Euteleostei. That would probably require splitting two additional monotypic superorders out of the Protacanthopterygii, and is probably not ideal due to the profusion of very small

taxa In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...

it would create. In fact, in some treatments, the jellynose fishes are even placed in yet another monotypic superorder, the Ateleopodomorpha. The Ateleopodidae have also been placed in the

Lampriformes Lampriformes is an order of ray-finned fish. Members are collectively called lamprids (which is more properly used for the Lampridae) or lampriforms, and unite such open-ocean and partially deep-sea Teleostei as the crestfishes, oarfish, opah ...

Myctophiformes The Myctophiformes are an order of ray-finned fishes consisting of two families of deep-sea marine fish, most notably the highly abundant lanternfishes (Myctophidae). The blackchins (Neoscopelidae) contain six species in three genera, while t ...

, which otherwise constitute additional superorders. The relationships of these to the taxa mentioned before is still not well resolved at all, and regardless whether one calls them Protacanthopterygii ''

sensu lato ''Sensu'' is a Latin word meaning "in the sense of". It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular co ...

'' or Euteleostei, the

phylogeny A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spec ...

of this group of moderately advanced Teleostei is in need of further study.Nelson (2006): pp.212-213, Diogo (2008)

References

* Diogo, Rui (2008): On the cephalic and pectoral girdle muscles of the deep sea fish ''Alepocephalus rostratus'', with comments on the functional morphology and phylogenetic relationships of the Alepocephaloidei (Teleostei). '' Anim. Biol.'' 58(1): 23–29. * FishBase (2000)
Order Ateleopodiformes
Version of 2000-OCT-17. Retrieved 2009-SEP-28. * Glare, P.G.W. (ed.) (1968-1982): ''

Oxford Latin Dictionary The ''Oxford Latin Dictionary'' (or ''OLD'') is the standard English lexicon of Classical Latin, compiled from sources written before AD 200. Begun in 1933, it was published in fascicles between 1968 and 1982; a lightly revised second edition ...

'' (1st ed.). Oxford University Press, Oxford. * Olney, John E. (1998): Ateleopodiformes. ''In:'' : ''Encyclopedia of Fishes'': 158. Academic Press, San Diego. * Nelson, Joseph S. (2006): ''

Fishes of the World ''Fishes of the World'' by the American ichthyologist Joseph S. Nelson (1937–2011) is a standard reference for fish systematics. Now in its fifth edition (2016), the work is a comprehensive overview of the diversity and classification of the ...

'' (4th ed.). John Wiley & Sons, Inc. * Woodhouse, S.C. (1910): ''English-Greek Dictionary - A Vocabulary of the Attic Language''. George Routledge & Sons Ltd., Broadway House, Ludgate Hill, E.C
Searchable JPEG fulltext

External links

* National Geographic News

September 22, 2009 (includes video of a possible new species of Jellynose) {{Taxonbar, from=Q719810, from2=Q9161604