Jellynose fish
Encyclopedia
The jellynose fishes or tadpole fishes are the small order
Ateleopodiformes. This group of ray-finned fish is monotypic
, containing a single family Ateleopodidae. It has about one dozen species
in four genera
, but these enigmatic fishes are in need of taxonomic revision.
The scientific name means "Ateleopus-shaped", from Ateleopus
(the type genus
) + the standard fish
order suffix
"-formes". It ultimately derives from Ancient Greek
atelís (ἆτελής, "imperfect") + pús (πούς, "foot") + Latin
forma ("external form"), the Greek part in reference to the reduced pectoral and ventral fins of the jellynoses.
fish. They are known from the Caribbean Sea
, eastern Atlantic, the western and central Indopacific and the Pacific coast of Central America
.
Their skeletons are largely cartilage
(hence "jellynose"), although they are true teleosts and not at all related to Chondrichthyes
. The heads are large, with a bulbous nose, and the (usually) elongated body tapers towards the tail. Their caudal fins are very small, and except for Guentherus it is merged with the long anal fin (which has 70 fin rays or more). The pelvic fins 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 ventral fins that are located behind (not below) the pectoral fins. Dorsal fin
s tend to be high, with a rather short base (9-13 rays, but in some as few as 3); they are placed just behind the head. They have 7 branchiostegal rays. The species have a range of sizes, the longest reaching 2 m (6.6 ft).
Most of the species are poorly-known, but the Highfin Tadpole Fish (Guentherus altivelis) is of potential interest for commercial fishing
.
, the jellynoses are often placed in the teleost superorder Stenopterygii
. 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 monotypic
superorder Cyclosquamata in an unranked clade
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 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
or Myctophiformes
, 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 or Euteleostei, the phylogeny of this group of moderately-advanced Teleostei is in need of further study.
The genera
and species
of jellynoses are:
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
Ateleopodiformes. This group of ray-finned fish is monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
, containing a single family Ateleopodidae. It has about one dozen species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
in four genera
Genera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...
, but these enigmatic fishes are in need of taxonomic revision.
The scientific name means "Ateleopus-shaped", from Ateleopus
Ateleopus
Ateleopus is a genus of ray-finned fish in the jellynose family . 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 replace the frog genus name Atelopus, which was deemed to be a spelling error...
(the type genus
Type genus
In biological classification, a type genus is a representative genus, as with regard to a biological family. The term and concept is used much more often and much more formally in zoology than it is in botany, and the definition is dependent on the nomenclatural Code that applies:* In zoological...
) + the standard fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate 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...
order suffix
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 or adjectives, and verb endings, which form the conjugation of verbs...
"-formes". It ultimately derives from Ancient Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
atelís (ἆτελής, "imperfect") + pús (πούς, "foot") + Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
forma ("external form"), the Greek part in reference to the reduced pectoral and ventral fins of the jellynoses.
Description and ecology
Jellynoses are deep-water, bottom-dwelling, marineOcean
An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...
fish. They are known from the Caribbean Sea
Caribbean Sea
The Caribbean Sea is a sea of the Atlantic Ocean located in the tropics of the Western hemisphere. It is bounded by Mexico and Central America to the west and southwest, to the north by the Greater Antilles, and to the east by the Lesser Antilles....
, eastern Atlantic, the western and central Indopacific and the Pacific coast of Central America
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...
.
Their skeletons are largely cartilage
Cartilage
Cartilage is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs...
(hence "jellynose"), although they are true teleosts and not at all related to Chondrichthyes
Chondrichthyes
Chondrichthyes or cartilaginous fishes are jawed fish with paired fins, paired nares, scales, two-chambered hearts, and skeletons made of cartilage rather than bone...
. The heads are large, with a bulbous nose, and the (usually) elongated body tapers towards the tail. Their caudal fins are very small, and except for Guentherus it is merged with the long anal fin (which has 70 fin rays or more). The pelvic fins 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 ventral fins that are located behind (not below) the pectoral fins. Dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
s tend to be high, with a rather short base (9-13 rays, but in some as few as 3); they are placed just behind the head. They have 7 branchiostegal rays. The species have a range of sizes, the longest reaching 2 m (6.6 ft).
Most of the species are poorly-known, but the Highfin Tadpole Fish (Guentherus altivelis) is of potential interest for commercial fishing
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 pursue fish far into the ocean under adverse conditions...
.
Systematics
Together with their relatives, the StomiiformesStomiiformes
Stomiiformes is an order of deep-sea ray-finned fishes of very diverse morphology. It includes for example dragonfishes, lightfishes, loosejaws, marine hatchetfishes and viperfishes. The order contains 4 families with more than 50 genera and almost 400 species...
, the jellynoses are often placed in the teleost superorder Stenopterygii
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 autapomorphic orders at best...
. 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 monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
superorder Cyclosquamata in an unranked clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
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 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
Lampriformes is an order of ray-finned fish. They are collectively called "lamprids" or lampriforms, and unite such open-ocean and partially deep-sea Teleostei as the crestfishes, oarfish, opahs and ribbonfishes...
or Myctophiformes
Myctophiformes
Myctophiformes is an order of ray-finned fish consisting of two families of deep-sea marine fish, most notably the highly abundant lanternfishes...
, 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 or Euteleostei, the phylogeny of this group of moderately-advanced Teleostei is in need of further study.
The genera
Genera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...
and species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of jellynoses are:
- AteleopusAteleopusAteleopus is a genus of ray-finned fish in the jellynose family . 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 replace the frog genus name Atelopus, which was deemed to be a spelling error...
(5 species) - Guentherus
- Guentherus altivela Osório, 1917 – Highfin Tadpole Fish
- Ijimaia
- Ijimaia antillarum Howell Rivero, 1935
- Ijimaia dofleini Sauter, 1905
- Ijimaia fowleri Howell Rivero, 1935
- Ijimaia loppei Roule, 1922 – Loppe's Tadpole Fish
- Ijimaia plicatellus (Gilbert, 1905) – Deepwater Ateleopodid
- Parateleopus
- Parateleopus microstomus Smith & Radcliffe, 1912
External links
- National Geographic News, "Bizzare Fish Found In Brazil", September 22, 2009 (includes video of a possible new species of Jellynose)