Chaetognatha

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, they are mostly pelagic; however about 20% of the known species are benthic, and can attach to algae and rocks. They are found in all marine waters, from surface tropical waters and shallow tide pools to the deep sea and polar regions. Most chaetognaths are transparent and are torpedo shaped, but some deep-sea species are orange. They range in size from .

Amiskwia is a genus of soft-bodied marine animals known from fossils of the Middle Cambrian Lagerstätten both in the Burgess Shale in British Columbia, Canada and the Maotianshan shales of Yunnan Province, China. It is interpreted as a member of the clade Gnathifera sensu lato or as a basal cucullophoran.

genus of worms

Sagittidae is a family of sagittoideans in the order Aphragmophora.

species of worm

Parasagitta is a genus of arrow worms (phylum Chaetognatha) in the family Sagittidae. At one time these arrow worms were classified in the genus Sagitta.

Eukrohniidae is a family of sagittoideans in the order Phragmophora. It consists of a single genus, Eukrohnia von Ritter-Záhony, 1909.

Spadellidae is a family of sagittoideans in the order Phragmophora. Spadellidae prey on plankton and commonly reside in the epipelagic zone of the ocean.

species of worm

Phragmophora is an order of sagittoideans in the phylum Chaetognatha.

Spadella is a genus of small, transparent marine invertebrates belonging to the family Spadellidae within the phylum Chaetognatha, commonly known as arrow worms. Unlike most chaetognaths, which are pelagic (free-swimming in open water), species of Spadella are benthic, meaning they live near the seafloor and often attach to substrates in shallow marine environments.

Aphragmophora is an order of sagittodieans in the phylum Chaetognatha.

Heterokrohnia is a genus of chaetognaths in the family Heterokrohniidae.

Krohnittidae is a family of chaetognaths in the order Aphragmophora. It consists of a single genus, Krohnitta von Ritter-Záhony, 1910.

Paraspadella is a genus of chaetognaths in the family Spadellidae. Paraspadella was originally considered as Spadella before a revision separated that genus into three genera: Spadella, Paraspadella, and Gephyrospadella, the last of which is now synonymised to Paraspadella. The initial division was based on previous knowledge of three groups of Spadella, in a similar manner in which Sagitta was divided into a family of genera. Paraspadella is differentiated from Spadella by the presence of disparate (digital) adhesive organs, present in the former to various degrees, but entirely absent in the

Timorebestia koprii is an extinct species of stem-group chaetognath (arrow worm relative) that lived about 520 million years ago, in the Cambrian. Its fossils are known from the Sirius Passet Lagerstätte in Greenland, and it was first described in 2024.

Krohnittellidae is a family of sagittoideans in the order Phragmophora. It consists of one genus, Krohnittella Germain & Joubin, 1912.

species of worm

species of worm