Cirrina
| Cirrina | |
|---|---|
| |
| Oral view of Cirrothauma murrayi showing single row of suckers and paired cirri | |
Scientific classification 
| |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Cephalopoda |
| Order: | Octopoda |
| Suborder: | Cirrina , 1916 sensu Felley et al., 2001 |
| Families | |
|
Opisthoteuthidae | |
| Synonyms | |
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Cirrina or Cirrata is a suborder and one of the two main divisions of octopuses. Cirrate octopuses have a small, internal shell and two fins on their head, while their sister suborder Incirrina has neither. The fins of cirrate octopods are associated with a unique cartilage-like shell in a shell sac. In cross-section, the fins have distinct proximal and distal regions, both of which are covered by a thin surface sheath of muscle.
The suborder is named for small, cilia-like strands (cirri) on the arms of the octopus, a pair for each sucker. These are thought to play some role in feeding, perhaps by creating currents of water that help bring food closer to the beak. Cirrate octopuses are noteworthy for lacking ink sacs.
Phylogeny[]
A molecular phylogeny based on mitochondrial and nuclear DNA marker sequences by Sanchez et al., 2018, shows that the Cirrina is paraphyletic, i.e. it is not a single clade. Instead, a clade containing Opisthoteuthidae and Cirroctopodidae is sister to the Octopodida, while a clade containing Cirroteuthidae and Stauroteuthidae is sister to the clade that contains those other groups.[1]
Classification[]
- CLASS CEPHALOPODA
- Subclass Nautiloidea: nautilus
- Subclass †Ammonoidea: ammonites
- Subclass Coleoidea
- Superorder Decapodiformes: squid, cuttlefish
- Superorder Octopodiformes
- Family †Trachyteuthididae (incertae sedis)
- Order Vampyromorphida: vampire squid
- Order Octopoda
- Genus †Keuppia (incertae sedis)
- Genus †Palaeoctopus (incertae sedis)
- Genus † (incertae sedis)
- Genus †Pohlsepia (incertae sedis)
- Genus †Proteroctopus (incertae sedis)
- Genus †Styletoctopus (incertae sedis)
- Suborder Cirrina: finned deep-sea octopus
- Family Opisthoteuthidae: umbrella octopus
- Family Cirroteuthidae
- Family Stauroteuthidae
- Family Cirroctopodidae
- Suborder Incirrina
References[]
- ^ Sanchez, Gustavo; Setiamarga, Davin H. E.; Tuanapaya, Surangkana; Tongtherm, Kittichai; Winkelmann, Inger E.; Schmidbaur, Hannah; Umino, Tetsuya; Albertin, Caroline; Allcock, Louise; Perales-Raya, Catalina; Gleadall, Ian; Strugnell, Jan M.; Simakov, Oleg; Nabhitabhata, Jaruwat (2018). "Genus-level phylogeny of cephalopods using molecular markers: current status and problematic areas". PeerJ. 6: e4331. doi:10.7717/peerj.4331. PMC 5813590. PMID 29456885.
External links[]
- Cirrata at the Tree of Life Web Project
- Cirrate male reproductive tract at the Tree of Life Web Project
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