Mollusca. Quem são: Mexilhões, lulas, polvos, caramujos, lesmas etc. Cerca de espécies viventes descritas e espécies fósseis.

Mollusca

1

Quem são:

Mexilhões, lulas, polvos, caramujos,

lesmas etc.

Cerca de 100.000 espécies viventes

descritas e 70.000 espécies fósseis.

Aplacophora

Polyplacophora

Bivalvia

7

Scaphopoda

9

yielded nearly identical topologies within Mollusca, except for relation-ships among basal gastropods and placements of the sea slug Pleurobranchaea and the bivalve Mytilus (Fig. 2 and Supplementary Fig. 5). High leaf stability scores for all OTUs (Supplementary Table 3) and strong support for most nodes suggest all OTUs were represented by sufficient data to be reliably placed. Remarkably, branch lengths were relatively uniform; cephalopods did not show long branches as previously reported in analyses of 18S and 28S1–3,10_.

All major lineages of Mollusca were monophyletic with strong support (bs 5 100%, pp 5 1.00). Importantly, there was strong support at all deep nodes, although the node placing Scaphopoda received moderate support in ML (bs 5 72%) but strong support in BI (pp 5 0.98). A clade including Aplacophora and Polyplacophora was unequivocally supported (bs 5 100%, pp 5 1.00) and placed sister to Conchifera, consistent with the Aculifera hypothesis. Moreover, we found strong support (bs 5 100%, pp 5 0.99) for a sister relationship between Neomeniomorpha and Chaetodermomorpha, supporting the Aplacophora hypothesis but contrary to previous molecular1–3,10_and

morphological4_{studies. To evaluate alternatives to the Aculifera and}

Aplacophora hypotheses, we used AU tests (Supplementary Table 5). These tests rejected the Testaria hypothesis, which allies chitons with the other shelled molluscs (P , 0.02) and placement of either aplacophoran taxon as sister to all other molluscs (both P , 0.01). Aculiferan monophyly supports interpretation of the Palaeozoic taxon ‘Helminthochiton’ thraivensis as possessing features intermediate between chitons and aplacophorans12_{, and interpretation of dorsal,}

serially arranged calcareous structures as a possible aculiferan synapo-morphy13_{. Specifically, the chaetoderm Chaetoderma}14 _{and some,}

but not all, neomenioids15 _{possess dorsal, serially repeated}

sclerite-secreting regions during development. Notably, chiton valves are not thought to be homologous to aculiferan sclerites16_{, although certain}

genes involved in patterning these structures may be. Our results high-light a need for developmental gene expression studies of aculiferans to address this issue.

Within a monophyletic Conchifera (bs 5 100%, pp 5 0.98), Gastro-poda and Bivalvia were supported as derived sister taxa (bs 5 100%, pp 5 1.0). Traditionally, a sister relationship between gastropods and bivalves, which relates the two most speciose lineages of molluscs, has received little consideration. However, this relationship has been recovered in molecular studies with relatively limited taxon sampling across Mollusca5,17_{. Similarities between the veliger larvae of}

gastro-pods and lamellibranch bivalves have been long recognized. Most notably, both possess larval retractor muscles and a velum muscle ring18_{. Another potential synapomorphy is loss of the anterior ciliary}

rootlet in locomotory cilia of gastropods and bivalves19_{. Because of}

strong support for a gastropod/bivalve clade in most analyses and the implications of this hypothesis for understanding molluscan evolu-tion, we propose the node-based name Pleistomollusca, which includes the last common ancestor of Gastropoda and Bivalvia and all descendents (Fig. 4). Etymology of this name (pleistos from Greek for ‘most’) recognizes the incredible species diversity of this clade of molluscs which we conservatively estimate to contain .95% of described mollusc species.

Sister to Pleistomollusca is Scaphopoda (albeit with moderate support in ML; bs 5 72%, pp 5 0.98) and Cephalopoda represents the sister taxon of all other conchiferan lineages sampled. Despite strong support values for a gastropod/bivalve clade, AU tests failed to reject Scaphopoda as sister to any other conchiferan lineage (P . 0.5). Given the limited sampling for Scaphopoda, additional data may help solidify its position. Nonetheless, all results presented here clearly refute the traditional view of a sister relationship between gastropods and cephalopods (Cyrtosoma; P , 0.01). Features thought to be diagnostic of this clade include a

well-the high degree of cephalization in gastropods and cephalopods has recently been suggested to have evolved independently20_.

The phylogenomic approach used here also holds promise for resolv-ing relationships within major lineages. For example, although their phylogeny has been widely debated, our broadly sampled caenogastropod subtree was strongly supported throughout (bs 5 100, pp 5 1.0) and consistent with previous morphological analysis21_{. We also recovered}

opisthobranchs paraphyletic with respect to Pulmonata, agreeing with recent morphological and molecular studies22_{. Additionally, our analyses}

confirm bivalve monophyly with deposit-feeding protobranchs sister to filter-feeding lamellibranchs.

To assess robustness of the reconstructed topology further, we examined the influences of matrix completeness, gene inclusion and substitution models on phylogenetic reconstruction (Supplementary Table 6). Analyses of the 200 and 100 best-sampled genes (Supplemen-tary Figs 6 and 7) recovered the same branching order and relative level of support among major lineages as the full data set. For gene inclusion, matrices of only non-ribosomal (Supplementary Fig. 8) and only ribo-somal protein genes (Supplementary Fig. 9) were analysed to address issues of different gene classes (for example, ribosomal proteins) bias-ing phylogenetic signal5_{. Support values for deep nodes inferred from}

non-ribosomal protein genes were generally weak and Aplacophora, Polyplacophora and Bivalvia were not recovered monophyletic. In contrast, analysis of only ribosomal protein genes recovered all major lineages monophyletic with strong support in BI but moderate support for most deep nodes in ML (see also ref. 17). Although ribosomal protein and non-ribosomal protein genes seem to be contributing different amounts of phylogenetic signal, support for most nodes was greater when all gene classes were included, in accordance with previous phylogenomic studies5,11_{. We also performed an analysis}

based on very conservative orthology determination using only the 243 genes for which our method and InParanoid identified the same Lottia sequence as orthologous to the primer taxon (Drosophila) sequence (see Methods). Branching order (Supplementary Fig. 10)

Gastropoda Bivalvia Scaphopoda Cephalopoda Neomeniomorpha Chaetodermomorpha Polyplacophora Annelida a Pleistomollusca Conchifera Mollusca Aculifera Aplacophora bs = 100, pp = 1.00 bs = 100, pp > 0.98 Figure 4|Deep molluscan phylogeny as inferred in the present study. Black circles represent nodes with bs 5 100 and pp 5 1.00. Gray circles represent nodes with bs 5 100 and pp $ 0.98. The actual specimens of Polyschides and Hanleya used in this study are shown. Photos are not to scale. A full-page version of this figure is presented in Supplementary Fig. 1.

LETTER

RESEARCH

LETTER

doi:10. 1038/nature103 82

Ph

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no

mi

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ve

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s

de

ep

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llu

sc

an

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la

ti

ons

h

ip

s

Ke vin M. K oc ot 1,Joh ann a T. Can non 1,Ch ris tian e Todt 2,Mat hew R. Ci tar ell a 3,And rea B. K ohn 3,Achi m Mey er 4,Sco tt R. San tos 1, Chr ist of fer Sch and er 2,Leo nid L. Mor oz 3,5 ,Ber nha rd Lieb 4& Ke nne th M. Ha la nych 1 Evo luti on ary rela ti ons hips amo ng the eig ht maj or line age s of Mol lus ca hav e rema ine d unre so lved des pite thei r div er sity and imp ort anc e. Prev iou sinv es tig ati on sof mol lusc an ph ylo geny ,bas ed pri mari ly on nuc le ar ri bos oma lgen e sequ ence s 1–3 or mor ph olo gica l data 4, hav e bee n un succ es sfu l at elu cid ati ng th ese rela ti ons hips . Re cent ly ,phyl ogen omic stud ie s usi ng doz ens to hund red s of gene s hav e gre atl y imp rove d our un der sta ndi ng of de ep ani mal rel ati on-shi ps 5. How eve r, lim ited gen omic res our ces spa nni ng mol lusc an div ers ity ha s pr eve nte d use of a ph ylo gen omic app roac h. Her e we use tr ans cri pto me and gen ome dat a from al lma jor lin eag es (ex cep t Mon opla cop hor a) and rec over a wel l-s upp ort ed top olo gy for Mol lus ca . Our resu lts stro ngl y sup por t the Acu lif era hypo th esis placing P olyplacophor a (ch itons )i n a cl ad e w it h a m on op hy le ti c Aplaco phora (worm-like mo lluscs) .A dd it io na lly ,w it hi nC on ch if er a, as is te r-ta xo nr el at io ns hi p be tw ee nG as tr op od a an d B iv al vi ai s su p-por ted .T his groupi ng has re ceived little consid er ati on and contains most (. 95%) molluscan species. Thus we prop ose the nod e-based name Pleistomollusca. In light of th ese results, we examined th ee volu-tion of morphological cha ra cters and fo und support for adva nced ce phalizatio n and she lls as possib ly ha ving multiple origins within Mollusca. Wi th ov er 100 ,0 00 de sc ri be d ext an tsp ec ie s in ei gh tma jo r line age s, Mo llu sc a is th e se con d mo st sp ec io se an im al phy lu m 6.M an y m ol lu sc s ar e eco no mi cal ly im por ta nt as fo od an d pr od uc er s of pea rl s and sh el ls wh er eas ot he rs ca use eco no mi cda ma ge as pe st s, bi of ou le rs an d in va si ve sp ec ie s. Mo llus cs ar e al so bi om ed ic al ly im po rt an t as mo del s fo r the st udy of br ai n or ga ni za tion ,le ar ni ng an d me mo ry as we ll as ve ct or s of par as ite s. Al th ou gh sh el le d mo llu sc s ha ve on e of th e be st fo ss il re co rd s of an y an im al gr ou p, evo lu tio na ry rel at io ns hi ps am on g ma jo r mo llu sc an lin ea ge s ha ve be en elu si ve . Mo rp hol og ic al di sp ar ity am on g th e m ajo r lin ea ge s of M ol lu sc a ha s prompted numerous conflicting phylo genetic hypotheses (Fig. 1). The vermiform C haetodermomorpha (also kno w n as C audo fo veata) and Neomenio m orph a( also known as Soleno gastres) traditionally hav ebeen considered to represent the plesi omorphic state of M ollusca because of their ‘simple’ interna lm orpho lo gy and la ck of shells 7.W he th er th es e two lineages constitute a monop hyle tic gr oup , A pl ac op hora 8,o ra pa ra ph yl et ic gr ad e 4, 9ha sbe en wi del y deb at ed .So me wo rk ers ha ve con -si der ed th e pr ese nc e of sc le ri tes a sy na pom or phy fo r a cla de Ac ul ife ra , un itin g Po ly pla co ph or a (c hi ton s; wh ic h ha ve bo th sc le ri te s an d sh el ls ) an d Ap la cop ho ra .In co nt ra st ,Po ly pl ac op ho ra ha s al te rn ati ve ly be en pl ac ed wi th Co nc hi fe ra (B iv al vi a, C ep ha lo pod a, Ga st ro po da, Mo no pl ac op ho ra and Sc ap ho pod a) in a cl ad e cal le d Te st ar ia un iti ng th e sh ell ed mo llu sc s 4. Mo rp ho lo gy ha s be en in ter pre ted to div id e Co nc hi fe ra int o a ga st ro pod /c ep ha lo pod cla de (C yr tos om a) an d a bi va lv e/s ca pho pod cl ad e( Di as om a) 6.U nf or tu na tel y, be cau se of va ry in g in te rp re ta tio ns of fe at ure s as der iv ed or pl esi om or phi c, a la ck of cl ear sy na po mo rp hi es, an d of te n unc le ar cha ra cte r ho mo lo gy ,th e ab ilit y of mo rp ho lo gy to re so lv e su ch dee p phy lo ge ne tic ev en ts is limi te d. Mol ecu lar inve sti gati on s of mol lus can phy log eny hav e rel ied pri mar ily on nucl ear ri bos oma l ge ne seq uen ces (18 S and 28S ) 1–3,1 0, an d hav e als o of fer ed littl e res olu tion . Ma ximu m lik eli hoo d (ML) an aly ses of 18S ,28S or both 1rec ove red mos t maj or line age s mo no-phy let ic, but sup por tat dee per nod es was ge ner all y wea k. Sub seq uent an aly ses of a com bine d data set (18 S, 28S ,16S ,cy toc hro me c oxi das e I an d his tone H3) 2yie lde d simi lar res ult s, na mely th at bi val ves wer e not mon oph yle tic an d sup por t val ue s at mos t de ep no des wer e low . Exp and in g on th is stu dy, fur th er work sup por ted a si ste r-t axon rel a-tio nshi p bet ween chi tons and mon opla coph ora ns (Se ria lia) but sup -por tat othe r dee p nod es was ge ner all y low 3.Mo reo ver, Mol lus ca wa s not rec over ed mon oph yle tic (a res ult sig nif ica ntly supp ort ed by App roxi mate ly Unb ias ed, AU, tes ts; Sup ple men tar y Tab le 1) pos si bly due to con tami nat ed neo men ioid seq uenc es 10. Mor pho log ica land tra dit iona lmol ecu lar phy log enet ic app roac hes hav e fa ile d to ro bus tly rec onst ruct mol lus c phy log eny. Nota bly, sev era l rec ent phy log eno mic stu die s (for exa mpl e, ref s 5 an d 11) ha ve sig nif i-can tly adv an ced our und ers tan din g of met azo an evol uti on by usi ng seq ue nces de riv ed from ge nom e an d tra nsc ri pto me dat a. Wit h th is app roac h, num ero us ort hol ogo us pro tei n-c odi ng ge nes can be ide n-tif ied and emp loy ed in phyl oge ny rec onst ruct ion. Many of the se ge nes ar e con stit uti ve ly exp res sed and can be eas ily rec ove red from ev en lim ite d exp res sed seq ue nce tag (E ST) sur ve ys. Ad dit iona lly , the se ge nes ar e usu all y in form ati ve for in fer rin g hig her -le vel phyl oge ny beca use of the ir con ser ve d na tur e due to the ir fun cti onal imp ort anc e. 1Department of Biological Sciences, Auburn University, 101 Rouse Life Sciences, Auburn, Alabama 36849, USA. 2Department of Biology and Centre for Geobiology, University of Bergen, P.O. Box 7800, NO-5020 Bergen, Norway. 3The Whitney Laboratory for Marine Bioscience, University of Florida, 9505 Ocean Shore Blvd., St. Augustine, Florida 32080, USA. 4Institute of Zoology, Johannes Gutenberg University, Mu ¨llerweg 6, D-55099 Mainz, Germany. 5Department of Neuroscience ,University of Florida, Gainesville, Florida 32611, USA.

Conchifera Polyplacophora Neomeniomorpha Chaetodermomorpha Conchifera Polyplacophora Chaetodermomorpha Neomeniomorpha

Conchifera

Polyplacophora

Neomeniomorpha Chaetodermomorpha

ab

c

Bivalvia Scaphopoda Gastr

opoda Cephalopoda Monoplacophora d Testaria Testaria Aculifer a Diasoma Cyrtosoma

Polyplacophora Neomeniomorpha Chaetodermomorpha Other Conchifera

Monoplacophora e Bivalvia Scaphopoda Gastr opoda Cephalopoda Monoplacophora Serialia f Fi gur e 1 | Lea din g hyp oth ese s of mol lusc an phyl oge ny. a, Ad eno pod a hyp oth esis pla cin g Ch aet ode rmo mor pha ba sal .b ,Hep aga st ral ia hyp oth esi s pla cin g Neo me nio mor pha bas al. c, Acu lif era hyp oth esi s pl aci ng Apl aco pho ra si ste r to Pol ypl aco ph ora. d, Se rial ia hyp oth esi s ally ing Pol ypl aco pho ra and Mo nop lac oph or a. e, Dia so ma and Cy rto so ma hy pot hes es ally ing biv alv es to sca pho pod s and gast ro pod s to cep ha lop ods ,res pec tivel y. f, Un nam ed hyp oth esis ,all ying sca ph opod s and cep ha lop ods . 00 MONTH 2 011 | V O L 000 | N A T URE | 1

Macmillan Publishers Limited. All rights reserved

©

2011

Nature, 07 de Setembro de 2011

Características gerais:

Simetria bilateral (ou secundariamente

assimétricos)

Não segmentados

Protostômios

Celomados (celoma reduzido)

O Manto:

13

Concha de um Gastropoda

15

Concha de um Cephalopoda

17

21

Quem são?

Cerca de 300 espécies

Vermiformes e cilíndricos

Sem concha

Possuem espículas calcárias

23

The aplacophoran group Caudofoveata, was placed intriguingly close to Cephalopoda (sometimes also including Patellogastro-poda) in all of our analyses, though with varying levels of support

(Figs. 1 and 2). But for this placement, no putative long-branch

attraction can be invoked based on examination of the sequence alignments. Some evidence for a Caudofoveata + Cephalopoda rela-tionship has previously been recovered via direct sequencing

phy-logenetics (Giribet et al. 2006), a phylogenomic analysis consisting

of 150 genes (Dunn et al., 2008), and a haemocyanin gene

phylog-eny (Lieb and Todt, 2008). If this relationship is further

corrobo-rated, there are interesting implications for shell evolution, suggesting the shell-less vermiform body of Caudofoveata is sec-ondarily derived, and not plesiomorphic as is widely accepted

(e.g.Haszprunar et al., 2008; Todt et al., 2008).

The monophyly of Mollusca as traditionally formulated was not recovered here because Solenogastres were nested inside an Annelida

(including Sipuncula) clade (Figs. 1 and 2) or the sipunculan and

brachiopod sequences were nested within molluscs (

Supplemen-tary Material S5). Although there is increasing morphological

evidence indicating Aplacophora (Solenogastres + Caudofoveata)

is not monophyletic (Haszprunar, 2000; Salvini-Plawen, 1980;

Salvini-Plawen and Steiner, 1996), we note here that Solenogastres

are notorious for presenting exogenous DNA contamination

problems (Okusu and Giribet, 2003). The only available 18S and

non-traditional placement here. New generation sequencing of Ex-pressed Sequence Tags and analytical techniques have provided promising preliminary data (Dunn, Wilson and Giribet, unpub-lished results), and will undoubtedly aid in future resolution of molluscan relationships.

Acknowledgments

The captain and crew of the R/V Robert Gordon Sproul, Cambria Colt, Eddie Kisfaludy and volunteers were essential for efficient sampling. We acknowledge a grant from UC Ship Funds Panel to NGW to lead the collection cruise. This study is based on work sup-ported by NSF Assembling the Tree of Life Program (Grant 0334932 to GG) and SIO start-up funds to GWR. We also acknowledge the NSF-funded CIPRES project for computational resources.

Appendix A. Supplementary data

Supplementary data associated with this article can be found, in

the online version, atdoi:10.1016/j.ympev.2009.07.028.

References

Baele, G., Raes, J., Van de Peer, Y., Vansteelandt, S., 2006. An improved statistical method for detecting heterotachy in nucleotide sequences. Mol. Biol. Evol. 23, Fig. 2. Cladogram of molluscan relationships comparing analytical approaches. Weakly-supported nodes are not collapsed to allow comparison between different phylogenetic reconstruction methods. Support for clades marked with an asterisk also include Patellogastropoda. BS, bootstrap; PP, posterior probability; JK, jackknife. All photographs by Greg Rouse.

192 N.G. Wilson et al. / Molecular Phylogenetics and Evolution 54 (2010) 187–193

Wilson NG, Rouse GW, Giribet G. (2010). Novel molecular data quantifies support for a molluscan clade Serialia (Monoplacophora + Polyplacophora). Molecular Phylogenetics & Evolution 54:187-193.

Dois táxons principais:

Neomeniomorpha (Solenogastres): é o

maior, com 25 famílias, possuem um sulco

pedal

Chaetodermomorpha (Caudofoveata):

táxon menor com 3 famílias, não possuem

pé

Chaetoderma canadense

Spengelomenia bathybia(Neomeniomorpha)

29

Polyplacophora

31

Quem são?

Cerca de 800 espécies

Chamados geralmente de QUÍTONS

Exclusivamente marinhos, abundantes na

região entremarés

Principalmente herbívoros

Tamanho varia de 3mm a 40cm

The aplacophoran group Caudofoveata, was placed intriguingly close to Cephalopoda (sometimes also including Patellogastro-poda) in all of our analyses, though with varying levels of support

(Figs. 1 and 2). But for this placement, no putative long-branch

attraction can be invoked based on examination of the sequence alignments. Some evidence for a Caudofoveata + Cephalopoda rela-tionship has previously been recovered via direct sequencing

phy-logenetics (Giribet et al. 2006), a phylogenomic analysis consisting

of 150 genes (Dunn et al., 2008), and a haemocyanin gene

phylog-eny (Lieb and Todt, 2008). If this relationship is further

corrobo-rated, there are interesting implications for shell evolution, suggesting the shell-less vermiform body of Caudofoveata is sec-ondarily derived, and not plesiomorphic as is widely accepted

(e.g.Haszprunar et al., 2008; Todt et al., 2008).

The monophyly of Mollusca as traditionally formulated was not recovered here because Solenogastres were nested inside an Annelida

(including Sipuncula) clade (Figs. 1 and 2) or the sipunculan and

brachiopod sequences were nested within molluscs (

Supplemen-tary Material S5). Although there is increasing morphological

evidence indicating Aplacophora (Solenogastres + Caudofoveata)

is not monophyletic (Haszprunar, 2000; Salvini-Plawen, 1980;

Salvini-Plawen and Steiner, 1996), we note here that Solenogastres

are notorious for presenting exogenous DNA contamination

problems (Okusu and Giribet, 2003). The only available 18S and

28S sequences for Solenogastres in this study (Helicoradomenia sp. AY145377 and AY145409, respectively) blast closely to poly-chaete sequences in GenBank, but not unambiguously enough to support their exclusion here. The high support for inclusion of Solenogastres in Annelida in this study is almost certainly caused by these two sequences, and thus this result should be reassessed. Moreover, such persistent contamination has generally limited the available data for Solenogastres, perhaps contributing to its

non-traditional placement here. New generation sequencing of Ex-pressed Sequence Tags and analytical techniques have provided promising preliminary data (Dunn, Wilson and Giribet, unpub-lished results), and will undoubtedly aid in future resolution of molluscan relationships.

Acknowledgments

The captain and crew of the R/V Robert Gordon Sproul, Cambria Colt, Eddie Kisfaludy and volunteers were essential for efficient sampling. We acknowledge a grant from UC Ship Funds Panel to NGW to lead the collection cruise. This study is based on work sup-ported by NSF Assembling the Tree of Life Program (Grant 0334932 to GG) and SIO start-up funds to GWR. We also acknowledge the NSF-funded CIPRES project for computational resources.

Appendix A. Supplementary data

Supplementary data associated with this article can be found, in

the online version, atdoi:10.1016/j.ympev.2009.07.028.

References

Baele, G., Raes, J., Van de Peer, Y., Vansteelandt, S., 2006. An improved statistical method for detecting heterotachy in nucleotide sequences. Mol. Biol. Evol. 23, 1397–1405.

Bourlat, S.J., Juliusdottir, T., Lowe, C.J., Freeman, R., Aronowicz, J., Kirschner, M., Lander, E.S., Thorndyke, M., Nakano, H., Kohn, A.B., Heyland, A., Moroz, L.L., Copley, R.R., Telford, M.J., 2006. Deuterostome phylogeny reveals monophyletic chordates and the new phylum Xenoturbellida. Nature 444, 85–88. Castresana, J., 2000. Selection of conserved blocks from multiple alignments for

their use in phylogenetic analyses. Mol. Biol. Evol. 17, 540–552.

De Laet, J.E., 2005. Parsimony and the problem of inapplicables in sequence data. In: Albert, V.A. (Ed.), Parsimony, Phylogeny, and Genomics. Oxford University Press, Oxford, pp. 81–116.

Fig. 2. Cladogram of molluscan relationships comparing analytical approaches. Weakly-supported nodes are not collapsed to allow comparison between different phylogenetic reconstruction methods. Support for clades marked with an asterisk also include Patellogastropoda. BS, bootstrap; PP, posterior probability; JK, jackknife. All photographs by Greg Rouse.

192 N.G. Wilson et al. / Molecular Phylogenetics and Evolution 54 (2010) 187–193

Wilson NG, Rouse GW, Giribet G. (2010). Novel molecular data quantifies support for a molluscan clade Serialia (Monoplacophora + Polyplacophora). Molecular Phylogenetics & Evolution 54:187-193.

Aspecto externo

Corte sagital da região anterior

Corte do ctenídio

39

Reprodução

Dióicos (gonocóricos)

Fecundação externa sem cópula

Ovos liberados em um envelope

espinhoso

Algumas espécies incubam os ovos

41

Características gerais:

Achatados e alongados

Pé ventral amplo

Concha com 8 (às vezes 7) placas

imbricadas

Conchas com uma camada mais interna

chamada HIPÓSTRACO

43

Características gerais:

Manto com uma expansão lateral variável

chamada CINTURÃO

6 a mais de 20 pares de ctenídios

1 par de nefrídios

Não possuem olhos ou tentáculos

Rádula presente

Monoplacophora

45

Quem são:

- Exclusivamente marinhos.

- Maioria das espécies está extinta.

- 11 espécies viventes descritas, de 3 gêneros.

- Os primeiros exemplares vivos foram

encontrados pela expedição dinamarquesa

“Galathea”, em 1952.

- A maioria vive em grandes profundidades

(2000 a 7000m) e medem entre 3 e 30mm.

Características Gerais

Concha única

Pé formando um fraco disco ventral 8 pares de músculos retratores 5 a 6 pares de ctenídios

2 pares de gônadas

6 a 7 pares de metanefrídios 2 pares de átrios no coração Cabeça reduzida, mas com rádula Com estilete cristalino e ânus posterior

Sem olhos, com tentáculos apenas ao redor da boca

51

Quem são?

Caramujos, caracóis, scargots, búzios

É o maior táxon de Mollusca

Cerca de 70.000 espécies descritas

Marinhos, dulciaquícolas e terrestres

Único grupo de Mollusca a invadir de

fato o ambiente terrestre

53

resulted in one tree of length 58,965 and a Consistency Index (CI) of 0.3598. Analyses excluding third codon positions included 8150 characters of which 1536 were constant, 1190 were variable but not parsimony informative and 5424 were parsimony informa-tive. MP analysis resulted in one tree of length 35,260 and CI 0.4053.

MP analyses (including or excluding third codon positions) recovered a clade in which Caenogastropoda and (Nerita, Haliotis and Lottia) were resolved as sister groups. With all data included, this clade was recovered as the sister group to a clade comprising Cephalopoda and Heterobranchia (as monophyletic sister groups) that contradicts gastropod monophyly (data not shown). Excluding

There were 12,500 trees (from 1.25 million ‘generations’) dis-carded for both runs of the Bayesian analyses excluding third co-don positions in the DNA alignment. This analysis recovered Gastropoda as monophyletic. Haliotis and Lottia were sister species comprising one of the two main clades within Gastropoda. This clade was the sister group of a clade in which Nerita was the sister group to the Apogastropoda (Fig. 1).

3.3. Phylogenetic position of Neritimorpha based on inferred amino acid sequences Vetigastropoda CEPHALOPODA POLYPLACOPHORA Neritimorpha Caenogastropoda Patellogastropoda Heterobranchia Katharina tunicata Octopus vulgaris Loligo bleekeri Haliotis rubra Nerita melanotragus Oncomelania hupensis Conus textile Lophiotoma cerithiformis Ilyanassa obsoleta Thais clavigera Rapana venosa Lottia digitalis Albinaria coerulea Cepaea nemoralis Myosotella myosotis Biomphalaria glabrata Onchidella celtica Pyramidella dolabrata Pupa strigosa Aplysia californica Siphonaria pectinata Roboastra europaea Elysia chlorotica Ascobulla fragilis 93 81 92 99 92 95 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 0.1 changes per site

Fig. 1. The maximum probability tree among those found during the Bayesian Monte Carlo Markov Chain analysis of DNA sequences from rRNA genes and coding regions from which third codon positions were omitted. Posterior probabilities (multiplied by 100 to improve legibility) are written above branches. Higher order group names are shown at the right of the figure. The scale bar represents 0.1 changes per base position in the alignment.

L.R. Castro, D.J. Colgan / Molecular Phylogenetics and Evolution 57 (2010) 918–923 921

Haliotis sp.

59

Hermissenda crassicornis

61

Aplysia dactylomela

63

Características gerais

Moluscos assimétricos, com uma concha

única e geralmente espiralada, na qual o

animal pode se recolher

Massa visceral e manto giram 90-180°

em relação ao pé (torção)

Pé muscular e rastejante

65

Cabeça com estatocistos e olhos (muitas

vezes reduzidos ou perdidos)

Possuem rádula geralmente complexa e

estilete cristalino

Sistemática

Sistemática complicada, em processo de

revisão

Tradicionalmente divididos em:

Prosobranchia: gastrópodos típicos, com a cavidade

do manto dirigida anteriormente, concha espiralada

Opistobranchia: tendência a redução da concha e

destorção

Pulmonata: gastrópodos terrestres

67

Origem e evolução

Origem provavelmente em

Monoplacophora

Eventos evolutivos mais marcantes:

Alongamento da concha e massa

visceral

Alongamento da concha e massa visceral

69

Evolução da

concha

conispiral

O Problema sanitário

A concha

Recolhimento do

pé e da cabeça

Locomoção

Alimentação

Conus sp. predando um peixe

87

Excreção

Como a imensa maioria dos animais

aquáticos, os Gastropoda são

amonotélicos

Primitivamente possuem 2 nefrídios,

sendo o direito perdido na maioria das

espécies

Sistema circulatório

Sistema aberto

Coração com 1 átrio e 1 ventrículo

Hemolinfa é bombeada inicialmente para

a cabeça e massa visceral

Sistema nervoso e sensorial

93

Reprodução

Dióicos ou hermafroditas

Liberação de espermatozóides

Véliger

97

Bivalvia

Quem são:

•

Ostras, mexilhões, berbigões, vôngole,

unha-de-velho, sururu, lambreta

•

Cerca de 8.000 espécies

•

Marinhos e dulciaquícolas

•

Animais bentônicos, micrófagos ou suspensívoros

Tivela stultorum

Spondylus sp.

Tridacna sp.

Características gerais:

•

Comprimidos lateralmente

•

Concha tipicamente com 2 valvas, articuladas

dorsalmente por um ligamento elástico e dentes

•

Conchas fechadas por ação de músculos adutores

•

Cabeça reduzida, sem olhos e rádula, mas olhos e

estatocistos podem ocorrer em outras regiões do

corpo

•

Pé geralmente comprimido lateralmente, sem sola

109

Características gerais:

•

1 par de ctenídios (brânquias) bipectinados,

utilizados juntamente com os palpos labiais na

alimentação

•

Cavidade do manto ampla

•

Bordas posteriores do manto frequentemente

fundidas para formar sifões inalante e exalante

Importância econômica

•

No mundo, foram produzidos em cultivos noa ano

de 2008 13.300.000 toneladas de bivalves,

movimentando recursos na ordem de 9 bilhões de

dólares

•

Na pesca, se retirou do mar em 2001 quase 2 milhões

de toneladas de bivalves

•

No Brasil foram pescados cerca de 2.000 toneladas

e produzidos em cultivos 15.500 toneladas, gerando

mais de 21 milhões de dólares

Cultivo em travesseiros (Camocim)

115

Lanterna para cultivo de

ostras

Cultivo de mexilhões em São Sebatião (SP)

117

Sistemática

•

Protobranchia

•

Metabranchia:

•

Filibranchia

Origem dos bivalves

•

Possivelmente a partir de um grupo de

Monoplacophora, no Cambriano

•

Um grupos de fósseis, os Rostroconcha, ja

apresentavam uma concha única arqueada,

comprimida lateralmente

Secção tranversal da margem da concha

Detalhe do palpo de um Protobranchia

125

Corte de um ctenídio, mostrando os filamentos branquiais e a ciliatura

127

Estrutura de uma brânquia Eulamellibranchia

Animação

131

Animação

133

Poromya granulata capturando um cumáceo

137

Radiação adaptativa dos

Bivalvia

Infaunais

Sifões de Panopea japonica

143

Bentônicos sésseis de

substrato consolidado

Mytilus sp.

Tridacna sp.

Bentônicos vágeis

149

Teredo sp.

151

Circulação e excreção

•

Coração com 2 átrios e 1 ventrículo

•

1 par de nefrídios

Sistema nervoso

Reprodução

•

Geralmente dióicos, poucas espécies são

hermafroditas

•

Algumas espécies podem mudar de sexo livremente,

como Ostrea edulis

•

A fecundação e externa, dando origem a uma larva

trocófora e posteriormente uma larva véliger

157

Véliger de um bivalve

159