A detailed list of previous studies aimed at determining the chemical composition of the molluscan radula is provided in Supplementary Table 2. Most of the previous research has been done on the Polyplacophora with the focus exclusively on the dominant lateral teeth [for reviews see 33–36, 46], except for one study on Lepidochitona cinerea determining the elemental composition of all toot types [32]. Many of these analyses focused on the Fe biomineralization and the phase transformations during maturation [e.g. 23, 29, 47–55]. Overall, in previous studies F, Na, Mg, Si, P, S, Cl, K, Ca, Fe, and Cu was detected in the dominant lateral teeth (=lateral teeth II) of Polyplacophora. For Lepidochitona cinerea, in our previous paper, we did not detect Cl, F, and Cu and in Acanthochitona fascicularis – no Si and Cu.
The following Fe proportions of mature dominant lateral teeth were previously determined in Polyplacophora: for A. fascicularis – 59.2% [56], 62% [51, 57] or few percent [58] were detected. For Plaxiphora – 86.6% [56], 17–27% [51], or 26.7% [59]; for Cryptochiton – 51.8% [47] or 69% [29]; for Ischnochiton – 62% [51]; for Onithochiton – 66% [51] or 0.2% [59]; for Cryptoplax – ~90 weight % in the cap, ~30 weight % in the core, junction zone, and basis [49]; and for Chiton – 97% [60] were detected. For mature L. cinerea, we previously [32] found Fe proportions of maximal 32% (atomic ratio, atomic %) and for A. fascicularis – maximal 29% in the dominant lateral teeth.
For Polyplacophora, P was previously reported [47, 49, 51, 59, 61] in form of iron phosphate [52, 62, 63] or apatitic calcium phosphate [58, 59, 61, 64–66]. F related to Ca [66, 67] was also previously reported for the dominant lateral teeth of chitons. In Acanthopleura [51, 58] and Onithochiton [51], Ca was abundant to maximal ~30 elemental % and P to maximal ~20 elemental %. For Lepidochitona cinerea, we detected Ca in proportions of maximal 8% and P to 7% and for Acanthochitona fascicularis to maximal 6% and P to 9%.
Additionally, Si [49, 51, 64, 65] and Mg [51, 59] were previously detected in the dominant lateral teeth of chitons. S was also previously detected [49]. It is associated with the tanning of the organic matrix and with the appearance of proteins [48]. Additionally, [68] detected Zi, K, F, S, Na, and Cl in radular segments of Clavarizona, [56] Ca, P, Mg, S, Na, Zi, K, Al, Cu, and Si in radulae of Acanthopleura and Plaxiphora, and [49] Mg (with max ~5.5 weight %), K (with max ~1.0 weight %), Na (with max ~2.0 weight %), Si (with max ~1.0 weight %), Al (with max ~0.5 weight %), and S (with max ~0.8 weight %) in Cryptoplax. These elements, except for Zi and Cu, which were not found, occurred in smaller proportions (0–5%) in both Lepidochitona cinerea and Acanthochitona fascicularis. For the central, lateral I, and marginal teeth we detected less minerals than in the dominant lateral teeth in both species.
In Cephalopoda, only one study on the radular chemistry exists, to the best of our knowledge. In Octopoda, [43] targeted, but did not detect Si and Fe. We here determined Na, S, Cu, Si, P, Cl, Ca, and Mg in the radula of Histioteuthis spec. and Loligo vulgaris with proportions <4%.
Within the Gastropoda, the Patellogastropoda received the most attention [41–43, 56, 69–81]. However, few studies focused on the overall radular composition, since most analyses, e.g. ashing and treatments with different acids or Raman spectroscopies, EDX, rather targeted the presence and crystalline shape of Fe and Si [e.g. 41, 69, 70, 72–77, 80, 81]. In fewer studies, other elements were of interest [e.g. 42, 43, 56, 71, 78, 79]. Overall, in Patellogastropoda, Na, Mg, Si, P, Cl, K, Ca, Fe, Cu, and S were previously found. For Patella vulgata, we here detected Na, Mg, Si, P, K, Ca, Fe, S, but no Cu and Cl. We additionally determined F. Similar to previous studies, we detected Si and Fe in high proportions in the dominant teeth (18–38%), whereas all other elements in smaller proportions only.
For the remaining gastropod taxa, only few analyses of the radular chemistry were conducted and usually the presence of elements, but not their proportions, could be determined. One of the earliest studies was done by [41] depicting results from Bergh, who performed complex chemical analyses of ashing and dissolving radulae from the Caenogastropods Charonia lampas (detecting P, Ca, and Fe), Lamellaria perspicua (detecting no Si), and Gibberulus gibberulus (probably detecting none of these elements, this is not clear) in different acids. Additionally, [41] presented his own results on the radulae of the Caenogastropod Tonna galea and the Heterobranch Helix nemoralis discovering P, Ca, and Fe in both by employing the same experiment. [42] was the first, who studied the radular chemistry in an elevated quantity of taxa and [43] proceeded. Overall, their protocols are rather complex, involving analytical chemistry methods (ashing, staining, boiling, treating with acids, and using diffusion column) or physics (radula’s refractive index). [42] determined rather the presence of elements and [43] specifically tested the occurrence of Si and Fe. For the Caenogastropoda Potamopyrgus antipodarum, Lacuna vincta, Murex branchialis, and Aporrhais pespelecani, the Heterobranchia Scaphander lignarius, Aplysia punctata, and Jorunna tomentosa, [43] determined no Si and no Fe. For the Heterobranchia (Cornu aspersum), [42] determined Si and P. She detected Si in specimens collected during winter and phosphoric acid (P) in specimens collected during spring. [82] performed EDX analyses on five specimen of C. aspersum detecting Ca in all specimen and Si in one, even though specimens were also inventoried in spring depicting the inconsistency of elements embedded. For the Vetigastropoda (Haliotis tuberculata), [42] detected Si, Ca, and Fe.
The following species were studied by [42] and [43], but for many species their results are contradictory. In the Caenogastropoda Littorina littorea, [42] detected Mg, P, Ca, and Fe, whereas [43] – no Ca and no Fe. Nucella lapillus and Buccinum undatum were also studied by [42], but the results are not clear from the publication, and [43] detected no Si and no Fe in both species. For the Vetigastropoda (Emarginula fissure and Calliostoma zizyphinum), [42] detected P, Ca, and Fe, whereas [43] determined the absence of Fe and Si. Then, [83] and [26, 84] were the first to close the existing gap in knowledge about the radular composition of Vetigastropoda. [83] detected Na, Mg, Si, Cl, Ca, and Fe (EDX), and [26, 84] – Mg, Cl, Ca, and Fe (EDX and inductively coupled plasma-optical emission spectrometry) in the limpet Megathura crenulata. Within Vetigastropoda, we detected Na, S, Cu, Si, P, Cl, Ca, and Mg; all of them in low proportions <2%. Cu and S were not documented before, whereas Fe was detected in previous studies [83, 84]. For the Neritimorpha, only one past study addresses the mineral content detecting S, Cl, K, Ca, Mg, Si, and Fe [85]. We additionally detected Na and P in Vittina turrita; all elements detected are abundant in very low proportions (<4%). In the Caenogastropoda, we detected Fe, Mg, Ca, Cl, P, F, Si, Cu, S, Na, and K. Cu, F, Na, Si, S, and Cl were not determined before. In all species, proportions are <6%. For the Heterobranchia, we detected more elements (Mg, Ca, Cl, P, F, Si, S, Na, K) than described in past publications [41–43, 82]. Mg, Cl, F, S, Na, and K were not detected before. All elements are abundant at proportions <15%.
Overall, the above data depicts that it is rather difficult to compare the percentages measured between studies, because in some weight percentages and in others atomic ratios were determined. Besides, methodology, sample preparation, and the analyzed sample itself (whole radula or individual radular parts) differs. In addition, the presence and abundance of elements could potentially be influenced by the food available (e.g. plants containing or lacking Si) or by the chemistry of the saliva. In some taxa, specifically carnivorous gastropods, the saliva is acid [e.g. 86, 87], so potentially the contact of the outermost radular teeth with the saliva leads to reduced proportions. Both ideas await further research.
The generally accepted hypothesis on radular mineralization evolution states that all gastropods – besides Patellogastropoda, Neritimorpha, and Vetigastropoda – probably lack Fe in the radula [e.g. 88–90]. However, Fe was detected previously in gastropod species [for Tonna galea, Charonia lampas, and Helix nemoralis see 41, for Littorina littorea see 42] and our own analyses determined it in Reymondia horei and Littorina littorea. Thus, this means that iron is not lacking, rather its proportions are reduced in these gastropod lineages (see Figure 1).
Previous studies relate the radular length to the ingesta type. Herbivorous taxa were found to possess longer radulae than carnivorous ones [91]. Littorinid species, feeding on algae covering rocks, were found to possess longer radulae than species feeding from plant surface [92–96]. For Patella species, it was determined that the radular length increases with increasing usage and wear [97] and, when algae are less abundant and the radula must thus be used more frequently to obtain the food necessary, its length increases [98].
In general, we detected a similar pattern for the species studied here as the longest radulae with the highest quantity of tooth rows were found in species foraging on harder ingesta types (medium-to-solid, solid, medium) and the shortest ones in soft-substrate feeders. We, however, could not directly relate herbivory with longer radulae and carnivorous feeding with shorter ones. We additionally detected some relationship between radular length and proportions of elements (e.g. in Patella vulgata), so potentially more mineralized radulae are longer, because their maturation and mineralization requires more time and a longer contact to the overlain epithelia in the radular sac and mineralization zone. However, this does not seem to be the case for every species, as Lepidochitona cinerea and Acanthochitona fascicularis have relatively short heavily mineralized radulae. Thus, in these polyplacophoran species, the overlain epithelia can presumably incorporate more minerals at the same time or the radular replacement rate is faster in P. vulgata in contrast to the one in the Polyplacophora. Unfortunately, the radular replacement rate is known for few taxa: for Polyplacophorans (Acanthopleura, Plaxiphora, Patelloida, Mopalia), a rate of 0.36–0.80 rows per day was determined [56, 99, 100] and for P. vulgata, a rate of 1.5 rows/day was described [101]. In Caenogastropoda, for Lacuna (Littorinidae), the rate of 3 rows/day [102], for three Littorina species (Littorinidae) – 5–6 rows/day depending on the temperature [2, 101], and for Pomatias elegans – 5.02 rows/day [2] was determined. For Heterobranchia, the rate of 2.9 rows/day in Lymnaea stagnalis [103], 5.02 rows/day in Agriolimax reticulatus [2], 3.6 rows/day in adult Helix aspersa [= Cornu aspersum in 2] was detected. For Cepaea nemoralis, the whole radula was found to be renewed within 30-35 days [104]. Thus, in general, a higher degree of mineralization is inversely related to the higher replacement rate (teeth that possess larger proportions of minerals are replaced slower). However, radular replacement seems to depend on many factors, such as water temperature, metabolic rates, or age of animals [101, 102, 105, 106]. Further studies on these questions are required.
In general, we detected that radulae of species, foraging on the solid ingesta, possess heavy mineralized teeth and species feeding on the soft ingesta show the smallest proportions. In biological materials, heterogeneities can have their origin in geometry, chemistry, and/or structure [for a review see 107]. In the dominant lateral teeth of chitons and limpets they have their origin in the distribution of the inorganic components and in the architecture of organic components [23, 25, 27–31]. We have previously correlated the hardness and elasticity values in Lepidochitona cinerea with the iron and the calcium proportions [32], which was previously also described for limpet teeth [24, 70, 74, 108] and for other chitons [23, 25, 29, 30]. For the paludomid gastropods, we previously measured elasticity modulus values ranging from 2 GPa at the tooth basis to 8 GPa in the cusp in solid substrate feeders, whereas soft substrate feeders possessed significantly softer teeth (4.6 GPa) [37, 38, 40]. In these species, we here detected inorganic elements in rather small proportions. We thus propose that specific cross-linking conditions of the chitin due to tanning [1], fiber arrangement, and density [22, 23, 26, 28, 31, 54, 109–111] rather cause the heterogeneities in mechanical properties. We previously also detected that the capability of wet teeth to rely on one another and to redistribute the mechanical stress increases the radula’s resistance to structural failure in paludomid gastropods [112, 113]. This altogether probably enables the feeding on harder ingesta types. Whether these mechanisms are also applicable for the other molluscan species, await further investigations.
Table 1. Systematic position of the taxa studied, list of specimens with collection number, locality and date of collection or fixation. The ingesta preferred, if known, and the ingesta categories assigned in this study are listed. Radular parameters, i.e. type, formula, length, width, area, and quantity of tooth rows, are documented for each specimen. C, central tooth; DC, dominant central tooth; DT, dominant lateral tooth or lateral tooth II; TM, thickened membrane, potentially reduced central tooth.
Class
|
Subclass
|
Species
|
Specimens
|
Ecology
|
Radula
|
|
N of specimens studied with EDX + SEM
|
Collection number
|
Source or locality of collection
|
Date of collection or fixation
|
Food or substrate
|
Reference for ecology
|
Ingesta category
|
Radular
type
|
Radular formula
|
Specimen no.
|
Length, µm
|
Width, µm
|
Area, µm2
|
N of tooth rows
|
Polyplacophora
|
Chitonida
|
Lepidochitona cinerea
(Linnaeus, 1767)
|
3 + 1
|
ZMH
154653
|
North Sea, at Husum, Germany
|
Autumn 2019
|
Algae from solid substrate
|
[156]
|
Solid
|
Docogloss
|
1 + DT + 1 + C + 1 + DT + 1
|
1
|
3375
|
375
|
1265625
|
39
|
2
|
3269
|
369
|
1206261
|
39
|
3
|
3109
|
354
|
1100586
|
39
|
Chitonida
|
Acanthochitona fascicularis
(Linnaeus, 1767)
|
2 + 1
|
#will be added
|
North Sea, at Roscoff, France
|
2018, 2019
|
Algae from solid substrate
|
[157]
|
Solid
|
Docogloss
|
1 + DT + 1 + C + 1 + DT + 1
|
1
|
7630
|
890
|
6790700
|
55
|
2
|
7527
|
872
|
6566587
|
54
|
3
|
7559
|
880
|
6652595
|
55
|
Cephalopoda
|
Oegopsida
|
Histioteuthis spec.
d'Orbigny [in Férussac & d'Orbigny], 1841
|
2
|
ZMH
11623/ 999
|
NE Atlantic, 46°29’24’’N
027°14’18’’W
-250m
|
12.06.1982
|
Fish, crustacea, Cephalopoda
|
[158]
|
Soft to solid
|
Homodont
|
2 + 1 + C + 1 + 2
|
1
|
868
|
464
|
402752
|
36
|
2
|
857
|
459
|
393363
|
36
|
Myopsida
|
Loligo vulgaris Lamarck, 1798
|
2 + 1
|
#will be added
|
Indonesia
|
Spring
2021
|
Fish, crustacea, Cephalopoda
|
[159]
|
Soft to solid
|
Homodont
|
2 + 1 + C + 1 + 2
|
1
|
6430
|
1480
|
9516400
|
45
|
2
|
6531
|
1485
|
9698535
|
46
|
3
|
6315
|
1369
|
8645235
|
45
|
Gastropoda
|
Patellogastropoda
|
Patella vulgata Linnaeus, 1758
|
2 + 1
|
#will be added
|
North Sea, at Roscoff, France
|
30.09.2020
|
Algae from rocks, macroalgae
|
[160]
|
Solid
|
Docogloss
|
3 + DT + 2 + 0 + 2 + DT + 3
|
1
|
36634
|
949
|
34765666
|
195
|
2
|
36862
|
962
|
35461244
|
197
|
3
|
35925
|
958
|
34416150
|
197
|
Vetigastropoda
|
Rochia conus
(Gmelin, 1791)
|
2 + 1
|
ZMH
154624
|
Pet shop
|
Summer
2019
|
Algae/ plants from corals and rocks
|
www.sealifebase.ca
|
Solid
|
Rhipidogloss
|
∞ + 5 + C + 5 + ∞
|
1
|
6070
|
980
|
5948600
|
102
|
2
|
6054
|
978
|
5920812
|
101
|
3
|
6103
|
968
|
5907704
|
102
|
Haliotis tuberculata Linnaeus, 1758
|
2 + 1
|
#will be added
|
Pet shop
|
Summer
2021
|
Macroalgae
|
[161]
|
Medium
|
Rhipidogloss
|
∞ + DT + 2 + C + 2 + DT + ∞
|
1
|
15945
|
3690
|
58837050
|
114
|
2
|
15763
|
3598
|
56715274
|
113
|
3
|
15899
|
3304
|
52530296
|
113
|
Neritimorpha
|
Vittina turrita
(Gmelin, 1791)
|
2 + 1
|
ZMH
154753
|
Pet shop
|
Summer 2020
|
solid substrates, but also porous ingesta
|
[162]
|
Medium to solid
|
Rhipidogloss, neritinomorph
|
40 + 1 + 1 + C + 1 + 1 + 40
|
1
|
17350
|
1210
|
20993500
|
150
|
2
|
17364
|
1205
|
20923620
|
151
|
3
|
18023
|
1305
|
23520015
|
149
|
Caenogastropoda
|
Lavigeria grandis
(Smith, 1881)
|
2 + 1
|
ZMH
150020/999
|
Zambia
08°43’25’’S
31°09’00’’E
|
30.11.2017
|
Algae from rocks
|
[163–166]
|
Solid
|
Taeniogloss
|
2 + 1 + C + 1 + 2
|
1
|
8120
|
900
|
7308000
|
85
|
2
|
8109
|
886
|
7184574
|
83
|
3
|
7906
|
749
|
5921594
|
85
|
Lavigeria nassa
(Woodward, 1859)
|
2 + 1
|
ZMH
119369/999
|
Zambia
08°29’23‘’S
30°28’46’’E
|
09.09.2016
|
Algae from rocks
|
[163, 164, 167–169]; personal
comment from collector (Heinz Büscher)
|
Solid
|
Taeniogloss
|
2 + 1 + C + 1 + 2
|
1
|
5160
|
430
|
2218800
|
112
|
2
|
5136
|
426
|
2187936
|
112
|
3
|
5004
|
435
|
2176740
|
110
|
Paramelania damoni
(Smith, 1881)
|
2 + 1
|
ZMH
150023/999
|
Zambia 08°34‘09‘’S 31°45‘02‘’E
|
05.05.2018
|
Algae from rocks and sand
|
[163–166, 168–172]
|
Soft to solid
|
Taeniogloss
|
2 + 1 + C + 1 + 2
|
1
|
2060
|
388
|
799280
|
98
|
2
|
2054
|
376
|
772304
|
97
|
3
|
1786
|
-
|
-
|
-
|
Cleopatra johnstoni
Smith, 1893
|
2 + 1
|
ZMB
220.102b
|
Zambia 09°20’866’S 28°43’886’E
|
19.12.2000
|
Algae from sand and mud
|
Unpublished work, personal comment
from collector (Matthias Glaubrecht)
|
Soft
|
Taeniogloss
|
2 + 1 + C + 1 + 2
|
1
|
2082
|
349
|
726618
|
70
|
2
|
2076
|
347
|
720372
|
71
|
3
|
-
|
326
|
-
|
-
|
Reymondia horei
(Smith, 1880)
|
2 + 1
|
ZMB
220.147
|
Tanzania Kigoma
|
26.02.1995
|
Algae from rocks
|
[163–166, 171, 172];
personal
comment from collectors (Heinz Büscher and Matthias Glaubrecht)
|
Solid
|
Taeniogloss
|
2 + 1 + C + 1 + 2
|
1
|
9240
|
820
|
7576800
|
176
|
2
|
9342
|
831
|
7763202
|
178
|
3
|
9108
|
803
|
7313724
|
176
|
Spekia zonata
(Woodward, 1859)
|
2 + 1
|
ZMB
220.077
|
Zambia 08°45‘547‘’S 31°05‘825‘’E
|
12.02.2000
|
Algae from rocks
|
[163–166, 168, 170–173];
personal comment from collectors (Heinz Büscher and Matthias Glaubrecht)
|
Solid
|
Taeniogloss
|
2 + 1 + C + 1 + 2
|
1
|
5660
|
560
|
3169600
|
138
|
2
|
5680
|
571
|
3243280
|
139
|
3
|
5589
|
577
|
3224853
|
138
|
Faunus ater
(Linnaeus, 1758)
|
2 + 1
|
ZMH
154630
|
Pet shop
|
Summer
2019
|
? found on soft and solid substrate
|
[174, 175]
|
Soft to solid ?
|
Taeniogloss
|
2 + 1 + C + 1 + 2
|
1
|
11480
|
510
|
5854800
|
170
|
2
|
11502
|
505
|
5808510
|
169
|
3
|
11899
|
489
|
5818611
|
170
|
Littorina littorea
(Linnaeus, 1758)
|
2 + 1
|
ZMH
154633
|
North Sea, at Husum, Germany
|
Autumn 2019
|
Algae, fleshy macroalgae, also from rocks
|
[176, 177, 178, 179]
|
Medium to solid
|
Taeniogloss
|
2 + 1 + C + 1 + 2
|
1
|
23180
|
370
|
8576600
|
280
|
2
|
23195
|
376
|
8721320
|
281
|
3
|
-
|
384
|
-
|
-
|
Paludomus siamensis
Blanford, 1903
|
2 + 1
|
ZMB
220.234
|
Thailand, Kanchanaburi,
14°26,3’N
98°51,0’E
|
08.02.2001
|
Not known
|
?
|
?
|
Taeniogloss
|
2 + 1 + C + 1 + 2
|
1,2,3
|
-
|
-
|
-
|
-
|
Anentome helena
(von dem Busch, 1847)
|
2 + 1
|
#will be added
|
Pet shop
|
Summer
2019
|
Gastropoda, fish eggs, shrimps, carrion
|
[180, 181]
|
Soft to solid
|
Stenogloss
|
1 + C + 1
|
1
|
2097
|
244
|
511668
|
61
|
2
|
2102
|
241
|
506582
|
60
|
3
|
2189
|
261
|
571329
|
61
|
Buccinum undatum
Linnaeus, 1758
|
2 + 1
|
#will be added
|
Biologische Anstalt Helgoland, Germany
|
May 2021
|
Polychaeta, fish eggs, bivalves, carrion, etc.
|
[182]
|
Soft to solid
|
Stenogloss
|
1 + C + 1
|
1
|
9660
|
1420
|
13717200
|
59
|
2
|
9641
|
1396
|
13458836
|
60
|
3
|
9701
|
1486
|
14415686
|
64
|
Heterobranchia
|
Onchidoris bilamellata
(Linnaeus, 1767)
|
2 + 1
|
#will be added
|
Biologische Anstalt Helgoland, Germany
|
May 2021
|
Soft parts of barnacles
|
[4, 183]
|
Medium
|
-
|
1 + DT + TM + DT + 1
|
1
|
2060
|
447
|
920820
|
34
|
2
|
2081
|
461
|
959341
|
34
|
3
|
-
|
474
|
-
|
-
|
Aeolidia papillosa
(Linnaeus, 1761)
|
2 + 1
|
#will be added
|
Biologische Anstalt Helgoland, Germany
|
May 2021
|
Sea anemone
|
[184–186]
|
Soft
|
-
|
DC
|
1
|
1460
|
410
|
598600
|
9
|
2
|
1471
|
420
|
617820
|
9
|
3
|
1507
|
429
|
646503
|
10
|
Polycera quadrilineata
(Müller, 1776)
|
2 + 1
|
#will be added
|
Biologische Anstalt Helgoland, Germany
|
May 2021
|
Encrusted Bryozoa
|
[187]
|
Medium
|
-
|
1 + 1 + TM + 1 + 1
|
1
|
2075
|
726
|
1506450
|
12
|
2
|
2082
|
731
|
1521942
|
12
|
3
|
-
|
-
|
-
|
-
|
Doris pseudoargus
Rapp, 1827
|
2 + 1
|
#will be added
|
Biologische Anstalt Helgoland, Germany
|
May 2021
|
Porifera
|
[188, 189]
|
Medium
|
Isodont
|
∞ + ∞ + C + ∞ + ∞
|
1
|
2350
|
2520
|
5922000
|
26
|
2
|
2461
|
2580
|
6349380
|
28
|
3
|
-
|
-
|
-
|
-
|
Cornu aspersum
(Müller, 1774)
|
2 + 1
|
ZMH
150005
|
Pet shop
|
2018
|
Various plant types
|
www.cabi.org/isc/
datasheet/26821
|
Soft to solid
|
Isodont
|
∞ + ∞ + C + ∞ + ∞
|
1
|
8000
|
3000
|
24000000
|
171
|
2
|
8123
|
3004
|
24401492
|
180
|
3
|
8206
|
3208
|
26324848
|
179
|
Table 2. Proportions of elements, radular length, area, quantity of tooth rows for the species foraging on certain ingesta types. N, quantity of teeth that contain the elements or quantity of radulae studied.
|
Ingesta type
|
Soft
|
Soft to solid
|
Medium
|
Medium to solid
|
Solid
|
Parameter
|
Mean
|
SD
|
N
|
Mean
|
SD
|
N
|
Mean
|
SD
|
N
|
Mean
|
SD
|
N
|
Mean
|
SD
|
N
|
Proportions of all elements, atomic %
|
1.88
|
2.80
|
64/
64
|
2.99
|
2.40
|
348/
348
|
5.58
|
6.24
|
164/
164
|
3.97
|
2.39
|
122/
122
|
6.33
|
12.50
|
688/
688
|
Radular length, µm
|
1964.00
|
241.55
|
5
|
5901.28
|
3945.67
|
20
|
7704.29
|
6710.08
|
9
|
20128.88
|
2923.74
|
5
|
7911.95
|
8319.09
|
24
|
Radular area, µm2
|
702397
|
45924
|
5
|
7406442
|
7723878
|
19
|
25206904
|
26887891
|
9
|
15106455
|
6172958
|
5
|
6144306
|
8488474
|
24
|
N of tooth rows
|
59
|
24
|
5
|
92
|
53
|
20
|
62
|
43
|
9
|
241
|
38
|
5
|
97
|
53
|
24
|
Fe-proportion, atomic %
|
0.00
|
0.00
|
0/
64
|
0.00
|
0.00
|
0/
348
|
0.00
|
0.00
|
0/
164
|
0.34
|
0.15
|
62/
122
|
13.69
|
10.17
|
120/
688
|
Mg-proportion, atomic %
|
0.34
|
0.24
|
41/
64
|
0.15
|
0.11
|
237/
348
|
0.68
|
0.43
|
114/
164
|
0.28
|
0.27
|
85/
122
|
0.42
|
0.62
|
426/
688
|
Ca-proportion, atomic %
|
3.11
|
2.49
|
12/
64
|
1.22
|
1.27
|
317/
348
|
3.15
|
3.22
|
150/
164
|
1.12
|
1.03
|
118/
122
|
1.84
|
1.80
|
561/
688
|
P-proportion, atomic %
|
0.69
|
0.95
|
22/
64
|
1.29
|
1.12
|
264/
348
|
1.91
|
2.06
|
132/
164
|
0.63
|
0.62
|
112/
122
|
1.11
|
1.64
|
405/
688
|
Cl-proportion, atomic %
|
0.26
|
0.43
|
27/
64
|
0.42
|
0.41
|
256/
348
|
0.98
|
0.27
|
6/
164
|
0.16
|
0.18
|
66/
122
|
0.21
|
0.15
|
248/
688
|
F-proportion, atomic %
|
0.00
|
0.00
|
0/
64
|
0.00
|
0.00
|
0/
348
|
0.65
|
0.74
|
136/
164
|
0.28
|
0.24
|
44/
122
|
0.38
|
0.48
|
156/
688
|
Si-proportion, atomic %
|
0.00
|
0.00
|
0/
64
|
0.22
|
0.20
|
116/
348
|
0.74
|
0.58
|
24/
164
|
0.50
|
0.46
|
120/
122
|
7.39
|
10.40
|
83/
688
|
Cu-proportion, atomic %
|
0.00
|
0.00
|
0/
64
|
0.19
|
0.12
|
94/
348
|
0.00
|
0.00
|
0/
164
|
0.00
|
0.00
|
0/
122
|
0.33
|
0.17
|
52/
688
|
S-proportion, atomic %
|
0.62
|
1.05
|
40/
64
|
0.36
|
0.25
|
241/
348
|
0.22
|
0.20
|
69/
164
|
0.32
|
0.20
|
104/
122
|
0.38
|
0.52
|
349/
688
|
Na-proportion, atomic %
|
0.38
|
0.28
|
58/
64
|
0.22
|
0.22
|
174/
348
|
0.22
|
0.31
|
69/
164
|
0.14
|
0.12
|
64/
122
|
0.66
|
0.70
|
230/
688
|
K-proportion, atomic %
|
0.02
|
0.01
|
14/
64
|
0.08
|
0.08
|
24/
348
|
0.09
|
0.08
|
10/
164
|
0.09
|
0.08
|
6/
122
|
0.39
|
0.40
|
40/
688
|