''Calispadella'' 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 ...

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, ''Calispadella alata'' Casanova & Moreau, 2005. It is differentiated from other species of

by the presence of an unusually long tail segment and a rare aspect of the lateral fins, similar to that of ''

Paraspadella ''Paraspadella'' is a genus of chaetognaths in the family 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 ...

gotoi'' Casanova, 1990. The species is noted by the complete development of seminal vesicles in juveniles and the use of lateral fins for buoyancy in the deep-sea waters where the specimens were found. It was the first to be described exclusively in the range of deep-sea hydrothermic vents.Hernández-Flores, R., McLelland, J. & Suárez-Morales, E. (2009)
Planktonic Chaetognatha of the Gulf of Mexico.
In: Felder, D. L. & Camp, D. K. (eds.), ''Gulf of Mexico Origin, Waters, and Biota'' (vol. 1, pp. 1165–1173). College Station: Texas A&M University Press. Although most of the species who live in ocean depths have delayed sexual maturity, ''Calispadella alata'' have their seminal vesicles already well developed. While they live in the ocean, they can also mate in populations that have limited resources since they are sexually precocious.

References

Chaetognatha Monotypic protostome genera {{Chaetognatha-stub