The redmouth whalefishes are two

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 deep-sea

whalefish The Cetomimoidea or whalefishes are a superfamily of small, deep-sea ray-finned fish. Formerly treated as either their own order (Cetomimiformes) due to their unusual anatomy, more recent studies incorporating genetic data confirm them to be dee ...

es 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 ...

''Rondeletia'', the only genus in the family Rondeletiidae. They are apparently close to the

velvet whalefish The velvet whalefish (''Barbourisia rufa'') is a deep-sea whalefish, the sole known member of its family Barbourisiidae. It is found throughout the tropical and temperate parts of the world's oceans, mainly in the Pacific near Japan and New Zeala ...

(''Barbourisia rufa''), and apparently also to the gibberfishes (Gibberichthyidae). The latter and the Rondeletiidae are the only known living fishes which have the mysterious Tominaga's organ. Like the plant genus of the same name, this genus is named after Guillaume Rondelet. Redmouth whalefishes are small fishes. ''Rondeletia bicolor'' grows to about 6 cm long or so. It is most commonly found in the northern

Atlantic The Atlantic Ocean is the second largest of the world's five oceanic divisions, with an area of about . It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery, it was known for se ...

, but has been documented from the eastern Pacific, as well, and presumably also occurs in the rest of the Atlantic. The better-known ''Rondeletia loricata'' is known from all oceans between 47°N–47°S; it has been recorded to reach a length of more than 9 cm when adult. Usually found in deep waters of tropical and temperate oceans around the world, down to 3,000 m or more, they make migrations up to shallower waters (around 100 m) at night to feed on

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

s and amphipods. The

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e occur in the surface waters, down to 50 m; previous to the onset of metamorphosis, they can be found in the uppermost few meters, descending as they mature.

Notochord The notochord is an elastic, rod-like structure found in chordates. In vertebrates the notochord is an embryonic structure that disintegrates, as the vertebrae develop, to become the nucleus pulposus in the intervertebral discs of the verteb ...

flexion occurs at around 4 mm

standard length Fish measurement is the measuring of individual fish and various parts of fish anatomy, their anatomies, for data used in many areas of ichthyology, including Taxonomy (biology), taxonomy and fishery biology. Overall length Standard length (SL) is ...

in ''R. loricata''.

Species

The currently recognized species in this genus are: * '' Rondeletia bicolor'' ( Goode &

Bean A bean is the seed of some plants in the legume family (Fabaceae) used as a vegetable for human consumption or animal feed. The seeds are often preserved through drying (a ''pulse''), but fresh beans are also sold. Dried beans are traditi ...

, 1895) * '' Rondeletia loricata'' ( T. Abe & Hotta, 1963)

References

External links

* * {{Taxonbar, from=Q2167047 Beryciformes