''Branchiostoma'' is one of the few living

genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...

lancelet The lancelets ( ), also known as amphioxi (: amphioxus ), consist of 32 described species of somewhat fish-like benthic filter feeding chordates in the subphylum Cephalochordata, class Leptocardii, and family Branchiostomatidae. Lancelets dive ...

s ( order Amphioxiformes). It is the

type Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type, collection of values used for computations. * File type * TYPE (DOS command), a command to display contents of a file. * ...

genus of

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 ...

Branchiostomatidae. Branchiostoma anatomy

These small vaguely eel- or snake-like animals are close relatives of

vertebrate Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebra ...

s. The

scientific name In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

means "gill-mouth", referring to their

anatomy Anatomy () is the branch of morphology concerned with the study of the internal structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old scien ...

– unlike vertebrates, they do not have a true

head A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple ani ...

(with a

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

capsule, eyes,

nose A nose is a sensory organ and respiratory structure in vertebrates. It consists of a nasal cavity inside the head, and an external nose on the face. The external nose houses the nostrils, or nares, a pair of tubes providing airflow through the ...

, a well-developed

brain The brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It consists of nervous tissue and is typically located in the head (cephalization), usually near organs for ...

etc.), but merely a mouth adjacent to the

gill A gill () is a respiration organ, respiratory organ that many aquatic ecosystem, aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow r ...

-slits, with the slightly enlarged

anterior Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

end of the

dorsal nerve cord The dorsal nerve cord is an anatomical feature found in chordate animals, mainly in the subphyla Vertebrata and Cephalochordata, as well as in some hemichordates. It is one of the five embryonic features unique to all chordates, the other fo ...

above and in front of them. It dislikes the light. ''Branchiostoma'' grows to lengths of 50 to 60 millimeters in length. Like all lancelets, they are

filter feeder Filter feeders are aquatic animals that acquire nutrients by feeding on organic matters, food particles or smaller organisms (bacteria, microalgae and zooplanktons) suspended in water, typically by having the water pass over or through a s ...

s that hide in the

sediment Sediment is a solid material that is transported to a new location where it is deposited. It occurs naturally and, through the processes of weathering and erosion, is broken down and subsequently sediment transport, transported by the action of ...

most of the time. The genus inhabits coastal waters throughout the world.

Species

*'' Branchiostoma africae'' Hubbs 1927 *'' Branchiostoma arabiae'' Webb 1957 *'' Branchiostoma bazarutense'' Gilchrist 1923 *'' Branchiostoma belcheri'' (Gray 1847) (Belcher's lancelet) *'' Branchiostoma bennetti'' Boschung & Gunter 1966 (Mud lancelet) *'' Branchiostoma bermudae'' Hubbs 1922 *'' Branchiostoma californiense'' Andrews 1893 (Californian lancelet) *'' Branchiostoma capense'' Gilchrist 1902 *'' Branchiostoma caribaeum'' Sundevall 1853 (Caribbean lancelet) *'' Branchiostoma elongatum'' Sundevall 1852 *'' Branchiostoma floridae'' Hubbs 1922 (Florida lancelet) *'' Branchiostoma gambiense'' Webb 1958 *'' Branchiostoma indicum'' (Willey 1901) *'' Branchiostoma japonicum'' (Willey 1897) (Pacific lancelet) *'' Branchiostoma lanceolatum'' (Pallas 1774) (European lancelet) *'' Branchiostoma leonense'' Webb 1956 *'' Branchiostoma longirostrum'' Boschung 1983 (Shellhash lancelet) *'' Branchiostoma malayanum'' Webb 1956 *'' Branchiostoma moretonense'' Kelly 1966;

nomen dubium In binomial nomenclature, a ''nomen dubium'' (Latin for "doubtful name", plural ''nomina dubia'') is a scientific name that is of unknown or doubtful application. Zoology In case of a ''nomen dubium,'' it may be impossible to determine whether a ...

*'' Branchiostoma nigeriense'' Webb 1955 *'' Branchiostoma platae'' Hubbs 1922 *'' Branchiostoma senegalense'' Webb 1955 *'' Branchiostoma tattersalli'' Hubbs 1922 *'' Branchiostoma virginiae'' Hubbs 1922 (Virginian lancelet)

References

External links

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Branchiostoma
Cephalochordata Taxa named by Oronzio Gabriele Costa Chordate genera {{chordate-stub