Chaetognatha
/ˌkiːtəɡˈnaθə
/ /ˌkiːtəɡˈneɪθə/plural noun Zoology
A small phylum of marine invertebrates that comprises the arrow worms.Instead, Rouse's conclusion that ‘groups such as the Arthropoda, Brachiopoda, Chaetognatha, Ectoprocta, Gastrotricha, Phoronida may have lost a prototroch’ is totally gratuitous, and remains unaddressed by his own data....
- Nielsen and Nielsen et al. come to generally comparable results, although sometimes the additional taxa Rotifera, Acanthocephala and Chaetognatha were included in Aschelminthes.
- Also unresolved are the phylogenetic positions of Cycloneuralia, Chaetognatha, Gnathostomulida, Cycliophora, and Micrognathozoa.
Derivatives
chaetognath
- Into the early 1990s most researchers and evidence suggested that the deuterostomes were composed of chordates, hemichordates, echinoderms, chaetognaths, and lophophorates.
- On the other hand, one species of parasitic nematode can reach 13 meters in length - it parasitizes the sperm whale - and adult nematomorphs, chaetognaths, and some priapulids are also visible to the naked eye.
- Perversely, they failed to include any sequences from rotifers, gnathostomulids, chaetognaths, or, in fact, anything that might actually be comparable to Acanthocephala.
Origin
Modern Latin (plural), from Greek khaitē 'long hair' + gnathos 'jaw'.