''Hemispadella'' is a
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of
chaetognaths
The Chaetognatha or chaetognaths (meaning ''bristle-jaws'') are a phylum of predatory marine worms that are a major component of plankton worldwide. Commonly known as arrow worms, about 20% of the known Chaetognatha species are benthic, and ca ...
in the
family
Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
Spadellidae
Spadellidae is a family of sagittoideans in the order Phragmophora. Spadellidae prey on plankton
Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). Th ...
. It consists of one species, ''Hemispadella dauvini'' Casanova, 1996.
[ The species, as the generic name implies, shares numerous, but not all, of the characteristics of Spadellidae; it shares a number of other characteristics with ]Heterokrohniidae
Heterokrohniidae is a family of sagittoideans in the order Phragmophora
Phragmophora is an order of sagittoideans in the phylum Chaetognatha.
Families
* Eukrohniidae Tokioka, 1965
*Heterokrohniidae Casanova, 1985Casanova, J. (1985). Descrip ...
. The ventral ganglion, poorly described in chaetognaths,[Bone, Q. & Pulsford, A. (1984). The sense organs and ventral ganglion of ''Sagitta'' (Chaetognatha). ''Acta Zoologica'', 65(4), 209–220.] is of similar size to the Heterokrohniidae, and the larger number of teeth, and the difference in appearance and function between the anterior and posterior teeth, are similarly characteristic. The relative tail size is similar to that of the Spadellidae, although the overall size is unprecedented among the Spadellidae. The more developed nature of transverse musculature and the basis for the lateral fins are as those of Spadellidae, as well.[
]
References
Chaetognatha
Monotypic protostome genera
{{Chaetognatha-stub