Dactylus - Misplaced Pages

Body part of cephalopods and some crustaceans For the foot in metric poetry, see Dactyl (poetry). For the suffix "-dactylus", see List of commonly used taxonomic affixes.

The leg of a squat lobster, with the dactylus labelled

The dactylus is the tip region of the tentacular club of cephalopods and of the leg of some crustaceans (see arthropod leg). In cephalopods, the dactylus is narrow and often characterized by the asymmetrical placement of suckers (i.e., the ventral expansion of the club) and the absence of a dorsal protective membrane. In crustaceans, the dactylus is the seventh and terminal segment of their thoracic appendages. In certain instances the dactylus, together with the propodus, form the claw.

The term dactylus means "finger" in Greek.

References

Walla, Graeme. "Comparative Morphology of Cephalopod Armature". The Octopus News Magazine Online. Retrieved 2 February 2024.
Robin, Ninon; van Bakel, Barry W. M.; Hyžný, Matúš; Cincotta, Aude; Garcia, Géraldine; Charbonnier, Sylvain; Godefroit, Pascal; Valentin, Xavier (27 December 2019). "The oldest freshwater crabs: claws on dinosaur bones". Scientific Reports. 9 (1): 20220. Bibcode:2019NatSR...920220R. doi:10.1038/s41598-019-56180-w. ISSN 2045-2322. PMC 6934782. PMID 31882600.

Cephalopod anatomy

Shell

Types

External	Ammonoid shell Argonautid eggcase Nautiloid shell Orthocone
Internal	Belemnoid guard Cirrate shell Cuttlebone Gladius (pen) Spirula shell Stylet

Features

External	Aperture Apex Callus Lirae Periostracum Sculpture Spire Sutures Umbilicus
Internal	Body chamber Camerae Nacre Phragmocone Septa Siphuncle Whorls

Mantle &
funnel

External anatomy	Dermal structures Fins (wings) Flotation devices ("secondary fins") Funnel–mantle locking apparatus Tail
Internal anatomy	Branchial hearts Ctenidia (gills) Hepatopancreas (digestive gland) Ink sac and ink Needham's sac Nephridia ("kidneys") Nidamental glands Osphradium Pericardial glands

Head &
limbs

Brachial crown	Arms Hectocotylus Tentacles Carpus Dactylus Manus Suckers and hooks
Buccal region	Aptychus Beak Odontophore Radula Spadix and antispadix
Occipital region	Nuchal crest (occipital crest) Nuchal folds (occipital folds) Occipital membrane Olfactory organ Nuchal organ
Other parts	Eyes Statocysts

General

Chromatophores
Photophores
Nervous system
- Squid giant axon
- Squid giant synapse

Developmental stages: Spawn → Paralarva (Doratopsis stage) → Juvenile → Subadult → Adult • Egg fossils • Protoconch (embryonic shell)

This animal anatomy–related article is a stub. You can help Misplaced Pages by expanding it.

Categories: