Figure 1.
Osedax mucofloris penetrating a bacterial mat resembling Beggiatoa.
Beggiatoa live in the restricted interface between hydrogen sulphide presence and oxygenated water [51]. O. mucofloris must therefore be in contact with toxic sulphide concentrations. Photographer: Helena Wiklund, Department of Zoology, Göteborg University, Sweden.
Figure 2.
Confocal laser scanning microscopy (CLSM) of the trunk of Osedax mucofloris females.
A: Dorso-lateral view of a complete specimen, lateral ciliary bands occupies half the length of the trunk. B: Dorsal view of the anterior part of the trunk, elliptical shaped cilia bundles are directed anteriorly from the lateral part of the trunk. C: Depth coded z-stack, the elliptical shaped cilia bundles constituting the lateral ciliary band are formed by ciliary tufts. D: Close-up of transverse section of a trunk. E: Transverse section of a trunk, note the muscularized dorsal blood vessel. F: Single z-stack image of the trunk musculature, longitudinal muscles beneath circular and diagonal muscles. Abbreviations: ciliary tufts (ct), circular muscles (cm), diagonal muscles (dm), elliptical ciliary bundles (ecb), lateral ciliary band (lcb), longitudinal muscles (lm), muscular gap (mg), palp (p), root structure (r), torn ovisac (to), trunk (t), dorsal blood vessel (dbv).
Figure 3.
CLSM (A–D) and differential interference contrast (DIC) light micrographs (E) of the anterior palps and pinnules of O. mucofloris females.
A: Lateral view of palps, pinnules increasing in length and development along the palp. B: Abfrontal view of the midsection of a palp, ciliary bands on each side. C: Close-up of palp musculature. D: Lateral view of the muscular palp-trunk connection. E: Close-up of the lateral ciliary band of a palp. Abbreviations: circular muscles (cm), lateral ciliary band (lcb), longitudinal muscles (lm), muscular bundles (bu), muscular gap (mg), oviduct (od), pinnules (pin).
Figure 4.
CLSM of the root system and pinnules of Osedax mucofloris females.
A: Single z-stack image of the ‘trunk-root system’ connection, note the bundles of longitudinal muscles. B: Musculature located by the ovisac, assumed to be the posterior end of the longitudinal dorsal blood vessel. C: Single z-stack image of pinnules, circular musculature encircling the pinnular loop, note the distal perikaryon and sensory cilia. D: Single z-stack image showing a longitudinal section of the pinnule in C, note the internal nerve. E: Depth coded z-stack, pinnule nerves in Osedax ‘yellow-collar’. Abbreviations: cilia (ci), circular muscles (cm), lateral ciliary band (lcb), longitudinal muscles (lm), nerve (n), perikaryon (pe).
Figure 5.
Diagram of a transverse section of the basal part of palps (A), DIC light micrographs of benzidine stained palps (B–D) and transverse 1.2 µm sections of O. mucofloris palps stained with toluidine blue (E–G).
A: Diagram of a transverse section at the basal part of the palp region. Circular musculature (continued green lines) encircles the longitudinal musculature (green broken lines) in a cylinder formation. Two gaps separate the longitudinal muscle bands. Black lines illustrate the motile lateral ciliary bands and two main palp nerves run along each palp as shown (blue dots). B: Pinnular loop filled with blood. C: Pinnular loops, broken lines and arrows indicate the assumed direction of blood flow. D: Midsection of palp, longitudinal blood vessels and pinnular loops visible. E: Transverse section of a pinnule, the pinnular loop enclosed by a membrane fusing in the centre. F: Transverse section of the distal part of a palp, arrow tips shows circular musculature. G: transverse section of the distal part of a palp, the two longitudinal blood vessels obvious. Abbreviations: circular muscles (cm), epidermis (ep), lateral ciliary band (lcb), left dorsal palp nerve (ldpn), left ventral palp nerve (lvpn), membrane fusion (mf), musculature (m), palp blood vessel (pbv), pinnule (pin), pinnular loop (pl), right dorsal palp nerve (rdpn), right ventral palp nerve (rvpn).
Figure 6.
DIC light micrographs of benzidine stained Osedax mucofloris.
A: Sketch of the path of the longitudinal trunk vessels into the root structure, drawn from the light microscope with a camera lucida of a benzidine stained O. mucofloris female. Trunk twisted in midsection. B: DIC light micrograph of a benzidine stained O. mucofloris female. Lateral view, trunk twisted in midsection. Ventral and dorsal blood vessels continues, folded, into the anterior part of the ovisac/root system. C: close up of blood vessels near ovisac. D: close up of blood vessels supplying more distally placed capillaries. E: Capillaries supplying tissue and endosymbionts. Abbreviations: blood traces (b), blood vessel (bv), capillaries (cap), dorsal blood vessel (dbv), egg cluster (ec), oviduct (od), ovisac (os), palp (p), root structure (r), trunk (t), ventral blood vessel (vbv).
Figure 7.
Schematic illustration of O2 distribution in the internal and external environments of Osedax mucofloris.
A: Osedax mucofloris extend its palps and pinnules, with large respiratory surfaces, into the overlying O2-rich water in order to uptake O2. O2 is then distributed to the buried root system through the extensive blood vascular system also supplying the heterotrophic endosymbionts. The O2 distribution to the root system is crucial as local uptake is not possible in the anoxic bone environment. The anoxic environment is partly produced by intense bacterial processes (green arrows) utilizing O2 at the bone surface. Hydrogen sulphide is produced by anoxic bacterial processes within the bone matrix during decomposition of organic content using sulphate. B: Schematic illustration of assumed blood flow in palp and pinnules, longitudinal section. Blue vessels carrying venous blood through afferent vessels, red vessels carrying arterial blood through efferent vessels. C: Schematic illustration of assumed blood flow in palp and pinnules, transverse section. Likewise blue vessels carries venous blood through afferent vessels, red vessels carries arterial blood through efferent vessels. Note that the palp blood vessels are created by an invagination of the basement membrane. Green indicates musculature.
Table 1.
Weight specific O2 consumption (MO2) of Osedax mucofloris.
Figure 8.
Experimental setups of micro sensor measurements and O2 profiles towards bone and tissue surfaces.
A: Depth profile of O2 towards bone surface, blue: agar, red: cuvette wall, green: bone surface. B: Depth profil of O2 towards tissue surface, blue: agar, red: cuvette wall, green: tissue surface. C: Schematic drawing of the micro sensor measuring path through the cuvette wall. D: Placement of measuring site on WB1, note the blackened areas indicating presence of ferrous sulphide. E: Close-up of measuring sites on WB1.
Table 2.
O2 concentration measured by micro sensors at the bone or tissue surface of Osedax mucofloris inhabiting whale bone in two cuvettes, WB1 and WB2.
Table 3.
O2 concentration measured by micro sensors in a mucus tube wall and at the epidermis of palps of Osedax mucofloris.
Figure 9.
O2 consumption of O. mucofloris females set in relation to O2 consumption of resting annelids as well as recent data of O2 consumption of R. pachyptila.
Graph modified from Cammen [18], the regression line (log R = −1.682+0.850 * log W) calculated from measurements of resting nonventilating annelids only. Dots: B1 (red), B2 (blue), B3 (green), C1 (purple), C2 (yellow). Triangles: Previous measured O2 consumption of R. pachyptila. No sulphide present in water when measuring: Red, blue [22] and green [23]; sulphide present in water during measurement: Purple [23]. Red Square: O2 consumption of resting Arenicola marina [52].
Figure 10.
Overview of bone types in experimental sampling device for recruitment of Osedax.
The experimental sampling devices were placed at 125 m depth off the coast of Tjärnö, Sweden (58°52.976N; 11°05.715E) in close vicinity to a minke whale carcass sunk in October 2003 [13].