''Chaetodon falcula'', the blackwedged butterflyfish or falcula butterflyfish, is a

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 ...

of marine

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 h ...

butterflyfish The butterflyfish are a group of conspicuous tropical marine fish of the family Chaetodontidae; the bannerfish and coralfish are also included in this group. The approximately 129 species in 12 genera are found mostly on the reefs of the Atla ...

belonging to the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Chaetodontidae. It is found in the Indian Ocean.

Description

''Chaetodon falcula'' has a white body which is marked with a number of thin vertical dark grey lines. It has two clear black saddle-like blotches on the dorsal part of the body, a vertical black eye band and a black caudal peduncle. The

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal c ...

anal Anal may refer to: Related to the anus *Related to the anus of animals: ** Anal fin, in fish anatomy ** Anal vein, in insect anatomy ** Anal scale, in reptile anatomy *Related to the human anus: ** Anal sex, a type of sexual activity involving s ...

and

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 ...

s are yellow. The yellow continues onto the body adjacent to the dorsal and anal fins. There are 12–13 spines in the dorsal fin and 23–25 soft rays while the anal fin contains 3 spines and 20–21 soft rays. This species attains a

total length Fish measurement is the measuring of individual fish and various parts of their anatomies. These data are used in many areas of ichthyology, including taxonomy and fisheries biology. Overall length * Standard length (SL) is the length of a fish ...

of .

Distribution

''Chaetodon falcula'' is found in the Indian Ocean where it occurs along the East African coast between Kenya and South Africa, Madagascar and the other western and central islands of the Indian Ocean, Sri Lanka, southern India, including the

Andaman and Nicobar Islands The Andaman and Nicobar Islands is a union territory of India consisting of 572 islands, of which 37 are inhabited, at the junction of the Bay of Bengal and the Andaman Sea. The territory is about north of Aceh in Indonesia and separated f ...

, and from the waters of western Thailand east as far as

Java Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's mos ...

. It occurs in the

Cocos (Keeling) Islands ) , anthem = "''Advance Australia Fair''" , song_type = , song = , image_map = Australia on the globe (Cocos (Keeling) Islands special) (Southeast Asia centered).svg , map_alt = Location of the Cocos (Keeling) Islands , map_caption = ...

, which are part of Australia, too.

Habitat and biology

''Chaetodon falcula'' is found at depths of . They are found on the reef edge and upper slope normally in habitats subjected to strong currents although the juveniles hide among corals. Typically seen in pairs or in small aggregations, of up to 20 fish. Their diet is made up feeds of the

polyps A polyp in zoology is one of two forms found in the phylum Cnidaria, the other being the medusa. Polyps are roughly cylindrical in shape and elongated at the axis of the vase-shaped body. In solitary polyps, the aboral (opposite to oral) end i ...

, worms,

sea anemones Sea anemones are a group of predatory marine invertebrates of the order Actiniaria. Because of their colourful appearance, they are named after the ''Anemone'', a terrestrial flowering plant. Sea anemones are classified in the phylum Cnidaria, ...

crustaceans Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean gro ...

sponge Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate throug ...

s, the feet of sea urchin and other invertebrates. This species forms distinct pairs to breed and the pelagic eggs are scattered in open water.

Systematics

''Chaetodon falcula'' was first formally described in 1795 by the

German German(s) may refer to: * Germany (of or related to) ** Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ge ...

physician A physician (American English), medical practitioner (Commonwealth English), medical doctor, or simply doctor, is a health professional who practices medicine, which is concerned with promoting, maintaining or restoring health through th ...

and naturalist Marcus Elieser Bloch (1723-1797) with the type locality given as

Tharangambadi Tharangambadi (), formerly Tranquebar ( da, Trankebar, ), is a town in the Mayiladuthurai district of the Indian state of Tamil Nadu on the Coromandel Coast. It lies north of Karaikal, near the mouth of a distributary named Uppanar of the Ka ...

in India. The specific name ''falcula'' is a diminutive of the

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 ...

''falx'' or ''falcis'' meaning a "sickle" or a "scythe" and is a reference to the wedge shaped black saddle blotches which Bloch illustrated as sickle-shaped, which they are not in modern photographs. With its

sister species In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

, the similar-looking

Pacific double-saddle butterflyfish ''Chaetodon ulietensis'', the Pacific double-saddle butterflyfish or false falcula butterflyfish, is a species of butterflyfish (family Chaetodontidae). It flourishes in coral-rich environments in the central Indo-Pacific region. Their range ext ...

(''C. ulietensis''), ''C. falcula'' belongs to the large subgenus ''Rabdophorus'' which might warrant recognition as a distinct

genus 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 nom ...

. Other fairly close relatives are the quite differently-shaped but similarly coloured lined (''C. lineolatus'') and spot-naped butterflyfishes (''C. oxycephalus''), while the

blue-cheeked butterflyfish The blue-cheeked butterflyfish (''Chaetodon semilarvatus'') is a species of marine ray-finned fish, a butterflyfish belonging to the family Chaetodontidae. It is found in the northwestern Indian Ocean. Description The bluecheek butterflyfish h ...

(''C. semilarvatus'') seems to be a far more basal lineage relative to all of these. The bluish vertical lines are present in all of these, while a white body with yellow behind and black on back and

caudal peduncle 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 ...

are only shared among the four less ancient species.

References

External links

* {{Taxonbar, from=Q1925587 falcula Fish described in 1795