Octopus vulgaris

Wild, Elvira, Wollesen, Tim, Haszprunar, Gerhard & Heß, Martin, 2015, Comparative 3 D microanatomy and histology of the eyes and central nervous systems in coleoid cephalopod hatchlings, Organisms Diversity & Evolution (New York, N. Y.) 15 (1), pp. 37-64 : 53-57

publication ID	https://doi.org/ 10.1007/s13127-014-0184-4
persistent identifier	https://treatment.plazi.org/id/B94787AC-FFE9-D256-FC93-19BDC6CCFB9D
treatment provided by	Felipe
scientific name	Octopus vulgaris
status

Treatment

Octopus vulgaris View in CoL

O. vulgaris is the only octobrachian species investigated in this study and has the smallest hatchlings ( Fig. 16 View Fig , supplement interactive Fig. 6 View Fig ; horizontal head diameter ca. 0.75 mm; see also Fig. 2f). A crown of eight short arms (all around 550– 650 μm long) embraces the remainder of an outer yolk sac ( Fig. 16a, b View Fig ). The microarchitecture of the peripheral nerve system of the arm crown resembles that of decabrachians, except it lacks tentacles. The integument is characterized by numerous tiny spines (bunches of “Kölliker bristles”; Fig. 16b–h View Fig ) that are less densely distributed in the cornea. The eyes point ca. 45° forward (Fig. 2f) in a horizontal plane ( Fig. 16d View Fig ), suspended in a voluminous anterior chamber. Anterior chamber organs are underdeveloped, if present. The lens of the O. vulgaris hatchling (diameter 120 μm, distal segment ca. 28 %) has a comparatively small cortex ( Fig. 3f View Fig ), the vitreous body is of average appearance, and the retina is completely developed histogenetically with a dark pigment layer ( Figs. 3f View Fig and 4f View Fig ). In its 3D aspect, the retina is a hemispheric cup, slightly flattened rostrally. As in S. officinalis , the optic lobes are kept at distance by the most frontal parts of the CNS. Frontally, they are strongly dented by the eye cups into a slightly concave shape (eyes not deformed by the optic lobes in this species). Optic and peduncle commissures were visible in histological slices even in the tiny specimen.

Subesophageal mass: In O. vulgaris , a suprabrachial commissure is present ( Fig. 7f View Fig ; sbc), bridging the esophagus between the dorsal rims (related to arm pair 1) of the horseshoe-shaped brachial lobe. The posterior part of the brachial lobe is fused with the pedal lobes, and brachiopedal connectives are not visible. An infrabrachial commissure (sensu Young 1971) has not been found. The brachio-palliovisceral connectives, in contrast, are well developed ( Fig. 10f View Fig ; bpvc). Projecting from the pedal lobes in the tiny hatchling only the basal branches of the funnel nerves, the anterior oculomotoric nerves and the superior antorbital nerves could be tracked ( Figs. 7f View Fig and 10f View Fig ). The dorsal parts of the magnocellular lobes are separated from the palliovisceral lobes. Posterior head retractor nerves lead upward instead of backward in this species.

The superior buccal lobes are located between the frontal portions of the optic lobes (as in hatchlings of S. officinalis ) and comparatively close to the superior frontal lobes in this species. Cerebro-subradular connectives lead down to the subradular ganglia, but a subradular commissure as described by Marquis (1989) could not be found. The neuropils of the superior and posterior buccal lobes (the latter only found in octobrachian species) are continuous, and only thin cerebrobuccal connectives lead dorsally straight to the inferior frontal lobes ( Fig. 8f View Fig ). Because of the low distance between the brachial lobe and the buccal and frontal lobes also, the bucco-brachial and the cerebrobrachial connectives are very short and appear as a fused axone bundle. The partitioning of the superior frontal lobes into lateral and median components is visible. The vertical lobe has a very characteristic shape with five lobules (sensu Nixon and Young 2003; see Fig. 2f: vtl @ 200 % or interactive suppl. Fig. 6 View Fig ) in contrast to the dome-shaped vertical lobes in the decabrachian species. Embedded in the pericaryal layer between superior frontal and posterior buccal lobes, the tiny neuropils of the subfrontal lobes can be detected ( Fig. 8f View Fig ; sftl) which are not easily delineated from the precommissural lobe.

The posterior buccal lobes are directly connected with the subvertical lobes, corresponding to the cerebral connectives of the decabrachian species. Conspicuous subpedunculate lobes are found on top of the dorsal basal lobes.

The statocysts of the O. vulgaris hatchling have circular profiles in tangential sections (i.e., unaffected by any shrinkage; max. diameter 280 μm; Fig. 16f, g View Fig ) and are oval shaped in side view, slightly tapered at both ends. The olfactory organs (115×100×35 μm 3) are placed directly behind the optic lobes just below their equator.